/*
 * Copyright © 2008-2011 Kristian Høgsberg
 * Copyright © 2011 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "config.h"

#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/input.h>
#include <linux/vt.h>
#include <assert.h>
#include <sys/mman.h>
#include <dlfcn.h>
#include <time.h>

#include <xf86drm.h>
#include <xf86drmMode.h>
#include <drm_fourcc.h>

#include <gbm.h>
#include <libudev.h>

#include "compositor.h"
#include "compositor-drm.h"
#include "shared/helpers.h"
#include "shared/timespec-util.h"
#include "gl-renderer.h"
#include "weston-egl-ext.h"
#include "pixman-renderer.h"
#include "pixel-formats.h"
#include "libbacklight.h"
#include "libinput-seat.h"
#include "launcher-util.h"
#include "vaapi-recorder.h"
#include "presentation-time-server-protocol.h"
#include "linux-dmabuf.h"
#include "linux-dmabuf-unstable-v1-server-protocol.h"

#ifndef DRM_CAP_TIMESTAMP_MONOTONIC
#define DRM_CAP_TIMESTAMP_MONOTONIC 0x6
#endif

#ifndef DRM_CLIENT_CAP_UNIVERSAL_PLANES
#define DRM_CLIENT_CAP_UNIVERSAL_PLANES 2
#endif

#ifndef DRM_CAP_CURSOR_WIDTH
#define DRM_CAP_CURSOR_WIDTH 0x8
#endif

#ifndef DRM_CAP_CURSOR_HEIGHT
#define DRM_CAP_CURSOR_HEIGHT 0x9
#endif

#ifndef GBM_BO_USE_CURSOR
#define GBM_BO_USE_CURSOR GBM_BO_USE_CURSOR_64X64
#endif

/**
 * List of properties attached to DRM planes
 */
enum wdrm_plane_property {
	WDRM_PLANE_TYPE = 0,
	WDRM_PLANE__COUNT
};

/**
 * Possible values for the WDRM_PLANE_TYPE property.
 */
enum wdrm_plane_type {
	WDRM_PLANE_TYPE_PRIMARY = 0,
	WDRM_PLANE_TYPE_CURSOR,
	WDRM_PLANE_TYPE_OVERLAY,
	WDRM_PLANE_TYPE__COUNT
};

/**
 * List of properties attached to a DRM connector
 */
enum wdrm_connector_property {
	WDRM_CONNECTOR_EDID = 0,
	WDRM_CONNECTOR_DPMS,
	WDRM_CONNECTOR__COUNT
};

/**
 * Represents the values of an enum-type KMS property
 */
struct drm_property_enum_info {
	const char *name; /**< name as string (static, not freed) */
	bool valid; /**< true if value is supported; ignore if false */
	uint64_t value; /**< raw value */
};

/**
 * Holds information on a DRM property, including its ID and the enum
 * values it holds.
 *
 * DRM properties are allocated dynamically, and maintained as DRM objects
 * within the normal object ID space; they thus do not have a stable ID
 * to refer to. This includes enum values, which must be referred to by
 * integer values, but these are not stable.
 *
 * drm_property_info allows a cache to be maintained where Weston can use
 * enum values internally to refer to properties, with the mapping to DRM
 * ID values being maintained internally.
 */
struct drm_property_info {
	const char *name; /**< name as string (static, not freed) */
	uint32_t prop_id; /**< KMS property object ID */
	unsigned int num_enum_values; /**< number of enum values */
	struct drm_property_enum_info *enum_values; /**< array of enum values */
};

struct drm_backend {
	struct weston_backend base;
	struct weston_compositor *compositor;

	struct udev *udev;
	struct wl_event_source *drm_source;

	struct udev_monitor *udev_monitor;
	struct wl_event_source *udev_drm_source;

	struct {
		int id;
		int fd;
		char *filename;
	} drm;
	struct gbm_device *gbm;
	struct wl_listener session_listener;
	uint32_t gbm_format;

	/* we need these parameters in order to not fail drmModeAddFB2()
	 * due to out of bounds dimensions, and then mistakenly set
	 * sprites_are_broken:
	 */
	int min_width, max_width;
	int min_height, max_height;
	int no_addfb2;

	struct wl_list plane_list;
	int sprites_are_broken;
	int sprites_hidden;

	void *repaint_data;

	int cursors_are_broken;

	bool universal_planes;

	int use_pixman;

	struct udev_input input;

	int32_t cursor_width;
	int32_t cursor_height;

	uint32_t pageflip_timeout;
};

struct drm_mode {
	struct weston_mode base;
	drmModeModeInfo mode_info;
};

enum drm_fb_type {
	BUFFER_INVALID = 0, /**< never used */
	BUFFER_CLIENT, /**< directly sourced from client */
	BUFFER_PIXMAN_DUMB, /**< internal Pixman rendering */
	BUFFER_GBM_SURFACE, /**< internal EGL rendering */
	BUFFER_CURSOR, /**< internal cursor buffer */
};

struct drm_fb {
	enum drm_fb_type type;

	int refcnt;

	uint32_t fb_id, stride, handle, size;
	const struct pixel_format_info *format;
	int width, height;
	int fd;
	struct weston_buffer_reference buffer_ref;

	/* Used by gbm fbs */
	struct gbm_bo *bo;
	struct gbm_surface *gbm_surface;

	/* Used by dumb fbs */
	void *map;
};

struct drm_edid {
	char eisa_id[13];
	char monitor_name[13];
	char pnp_id[5];
	char serial_number[13];
};

/**
 * Pending state holds one or more drm_output_state structures, collected from
 * performing repaint. This pending state is transient, and only lives between
 * beginning a repaint group and flushing the results: after flush, each
 * output state will complete and be retired separately.
 */
struct drm_pending_state {
	struct drm_backend *backend;
};

/**
 * A plane represents one buffer, positioned within a CRTC, and stacked
 * relative to other planes on the same CRTC.
 *
 * Each CRTC has a 'primary plane', which use used to display the classic
 * framebuffer contents, as accessed through the legacy drmModeSetCrtc
 * call (which combines setting the CRTC's actual physical mode, and the
 * properties of the primary plane).
 *
 * The cursor plane also has its own alternate legacy API.
 *
 * Other planes are used opportunistically to display content we do not
 * wish to blit into the primary plane. These non-primary/cursor planes
 * are referred to as 'sprites'.
 */
struct drm_plane {
	struct wl_list link;

	struct weston_plane base;

	struct drm_output *output;
	struct drm_backend *backend;

	enum wdrm_plane_type type;

	uint32_t possible_crtcs;
	uint32_t plane_id;
	uint32_t count_formats;

	struct drm_property_info props[WDRM_PLANE__COUNT];

	/* The last framebuffer submitted to the kernel for this plane. */
	struct drm_fb *fb_current;
	/* The previously-submitted framebuffer, where the hardware has not
	 * yet acknowledged display of fb_current. */
	struct drm_fb *fb_last;
	/* Framebuffer we are going to submit to the kernel when the current
	 * repaint is flushed. */
	struct drm_fb *fb_pending;

	int32_t src_x, src_y;
	uint32_t src_w, src_h;
	uint32_t dest_x, dest_y;
	uint32_t dest_w, dest_h;

	uint32_t formats[];
};

struct drm_output {
	struct weston_output base;
	drmModeConnector *connector;

	uint32_t crtc_id; /* object ID to pass to DRM functions */
	int pipe; /* index of CRTC in resource array / bitmasks */
	uint32_t connector_id;
	drmModeCrtcPtr original_crtc;
	struct drm_edid edid;

	/* Holds the properties for the connector */
	struct drm_property_info props_conn[WDRM_CONNECTOR__COUNT];

	enum dpms_enum dpms;
	struct backlight *backlight;

	bool state_invalid;

	int vblank_pending;
	int page_flip_pending;
	int destroy_pending;
	int disable_pending;

	struct drm_fb *gbm_cursor_fb[2];
	struct weston_plane cursor_plane;
	struct weston_view *cursor_view;
	int current_cursor;

	struct gbm_surface *gbm_surface;
	uint32_t gbm_format;

	/* Plane for a fullscreen direct scanout view */
	struct weston_plane scanout_plane;

	/* The last framebuffer submitted to the kernel for this CRTC. */
	struct drm_fb *fb_current;
	/* The previously-submitted framebuffer, where the hardware has not
	 * yet acknowledged display of fb_current. */
	struct drm_fb *fb_last;
	/* Framebuffer we are going to submit to the kernel when the current
	 * repaint is flushed. */
	struct drm_fb *fb_pending;

	struct drm_fb *dumb[2];
	pixman_image_t *image[2];
	int current_image;
	pixman_region32_t previous_damage;

	struct vaapi_recorder *recorder;
	struct wl_listener recorder_frame_listener;

	struct wl_event_source *pageflip_timer;
};

static struct gl_renderer_interface *gl_renderer;

static const char default_seat[] = "seat0";

static inline struct drm_output *
to_drm_output(struct weston_output *base)
{
	return container_of(base, struct drm_output, base);
}

static inline struct drm_backend *
to_drm_backend(struct weston_compositor *base)
{
	return container_of(base->backend, struct drm_backend, base);
}

static int
pageflip_timeout(void *data) {
	/*
	 * Our timer just went off, that means we're not receiving drm
	 * page flip events anymore for that output. Let's gracefully exit
	 * weston with a return value so devs can debug what's going on.
	 */
	struct drm_output *output = data;
	struct weston_compositor *compositor = output->base.compositor;

	weston_log("Pageflip timeout reached on output %s, your "
	           "driver is probably buggy!  Exiting.\n",
		   output->base.name);
	weston_compositor_exit_with_code(compositor, EXIT_FAILURE);

	return 0;
}

/* Creates the pageflip timer. Note that it isn't armed by default */
static int
drm_output_pageflip_timer_create(struct drm_output *output)
{
	struct wl_event_loop *loop = NULL;
	struct weston_compositor *ec = output->base.compositor;

	loop = wl_display_get_event_loop(ec->wl_display);
	assert(loop);
	output->pageflip_timer = wl_event_loop_add_timer(loop,
	                                                 pageflip_timeout,
	                                                 output);

	if (output->pageflip_timer == NULL) {
		weston_log("creating drm pageflip timer failed: %m\n");
		return -1;
	}

	return 0;
}

/**
 * Get the current value of a KMS property
 *
 * Given a drmModeObjectGetProperties return, as well as the drm_property_info
 * for the target property, return the current value of that property,
 * with an optional default. If the property is a KMS enum type, the return
 * value will be translated into the appropriate internal enum.
 *
 * If the property is not present, the default value will be returned.
 *
 * @param info Internal structure for property to look up
 * @param props Raw KMS properties for the target object
 * @param def Value to return if property is not found
 */
static uint64_t
drm_property_get_value(struct drm_property_info *info,
		       drmModeObjectPropertiesPtr props,
		       uint64_t def)
{
	unsigned int i;

	if (info->prop_id == 0)
		return def;

	for (i = 0; i < props->count_props; i++) {
		unsigned int j;

		if (props->props[i] != info->prop_id)
			continue;

		/* Simple (non-enum) types can return the value directly */
		if (info->num_enum_values == 0)
			return props->prop_values[i];

		/* Map from raw value to enum value */
		for (j = 0; j < info->num_enum_values; j++) {
			if (!info->enum_values[j].valid)
				continue;
			if (info->enum_values[j].value != props->prop_values[i])
				continue;

			return j;
		}

		/* We don't have a mapping for this enum; return default. */
		break;
	}

	return def;
}

/**
 * Cache DRM property values
 *
 * Update a per-object array of drm_property_info structures, given the
 * DRM properties of the object.
 *
 * Call this every time an object newly appears (note that only connectors
 * can be hotplugged), the first time it is seen, or when its status changes
 * in a way which invalidates the potential property values (currently, the
 * only case for this is connector hotplug).
 *
 * This updates the property IDs and enum values within the drm_property_info
 * array.
 *
 * DRM property enum values are dynamic at runtime; the user must query the
 * property to find out the desired runtime value for a requested string
 * name. Using the 'type' field on planes as an example, there is no single
 * hardcoded constant for primary plane types; instead, the property must be
 * queried at runtime to find the value associated with the string "Primary".
 *
 * This helper queries and caches the enum values, to allow us to use a set
 * of compile-time-constant enums portably across various implementations.
 * The values given in enum_names are searched for, and stored in the
 * same-indexed field of the map array.
 *
 * @param b DRM backend object
 * @param src DRM property info array to source from
 * @param info DRM property info array to copy into
 * @param num_infos Number of entries in the source array
 * @param props DRM object properties for the object
 */
static void
drm_property_info_populate(struct drm_backend *b,
		           const struct drm_property_info *src,
			   struct drm_property_info *info,
			   unsigned int num_infos,
			   drmModeObjectProperties *props)
{
	drmModePropertyRes *prop;
	unsigned i, j;

	for (i = 0; i < num_infos; i++) {
		unsigned int j;

		info[i].name = src[i].name;
		info[i].prop_id = 0;
		info[i].num_enum_values = src[i].num_enum_values;

		if (src[i].num_enum_values == 0)
			continue;

		info[i].enum_values =
			malloc(src[i].num_enum_values *
			       sizeof(*info[i].enum_values));
		assert(info[i].enum_values);
		for (j = 0; j < info[i].num_enum_values; j++) {
			info[i].enum_values[j].name = src[i].enum_values[j].name;
			info[i].enum_values[j].valid = false;
		}
	}

	for (i = 0; i < props->count_props; i++) {
		unsigned int k;

		prop = drmModeGetProperty(b->drm.fd, props->props[i]);
		if (!prop)
			continue;

		for (j = 0; j < num_infos; j++) {
			if (!strcmp(prop->name, info[j].name))
				break;
		}

		/* We don't know/care about this property. */
		if (j == num_infos) {
#ifdef DEBUG
			weston_log("DRM debug: unrecognized property %u '%s'\n",
				   prop->prop_id, prop->name);
#endif
			drmModeFreeProperty(prop);
			continue;
		}

		if (info[j].num_enum_values == 0 &&
		    (prop->flags & DRM_MODE_PROP_ENUM)) {
			weston_log("DRM: expected property %s to not be an"
			           " enum, but it is; ignoring\n", prop->name);
			drmModeFreeProperty(prop);
			continue;
		}

		info[j].prop_id = props->props[i];

		if (info[j].num_enum_values == 0) {
			drmModeFreeProperty(prop);
			continue;
		}

		if (!(prop->flags & DRM_MODE_PROP_ENUM)) {
			weston_log("DRM: expected property %s to be an enum,"
				   " but it is not; ignoring\n", prop->name);
			drmModeFreeProperty(prop);
			info[j].prop_id = 0;
			continue;
		}

		for (k = 0; k < info[j].num_enum_values; k++) {
			int l;

			for (l = 0; l < prop->count_enums; l++) {
				if (!strcmp(prop->enums[l].name,
					    info[j].enum_values[k].name))
					break;
			}

			if (l == prop->count_enums)
				continue;

			info[j].enum_values[k].valid = true;
			info[j].enum_values[k].value = prop->enums[l].value;
		}

		drmModeFreeProperty(prop);
	}

#ifdef DEBUG
	for (i = 0; i < num_infos; i++) {
		if (info[i].prop_id == 0)
			weston_log("DRM warning: property '%s' missing\n",
				   info[i].name);
	}
#endif
}

/**
 * Free DRM property information
 *
 * Frees all memory associated with a DRM property info array.
 *
 * @param info DRM property info array
 * @param num_props Number of entries in array to free
 */
static void
drm_property_info_free(struct drm_property_info *info, int num_props)
{
	int i;

	for (i = 0; i < num_props; i++)
		free(info[i].enum_values);
}

static void
drm_output_set_cursor(struct drm_output *output);

static void
drm_output_update_msc(struct drm_output *output, unsigned int seq);

static int
drm_plane_crtc_supported(struct drm_output *output, struct drm_plane *plane)
{
	return !!(plane->possible_crtcs & (1 << output->pipe));
}

static struct drm_output *
drm_output_find_by_crtc(struct drm_backend *b, uint32_t crtc_id)
{
	struct drm_output *output;

	wl_list_for_each(output, &b->compositor->output_list, base.link) {
		if (output->crtc_id == crtc_id)
			return output;
	}

	wl_list_for_each(output, &b->compositor->pending_output_list,
			 base.link) {
		if (output->crtc_id == crtc_id)
			return output;
	}

	return NULL;
}

static struct drm_output *
drm_output_find_by_connector(struct drm_backend *b, uint32_t connector_id)
{
	struct drm_output *output;

	wl_list_for_each(output, &b->compositor->output_list, base.link) {
		if (output->connector_id == connector_id)
			return output;
	}

	wl_list_for_each(output, &b->compositor->pending_output_list,
			 base.link) {
		if (output->connector_id == connector_id)
			return output;
	}

	return NULL;
}

static void
drm_fb_destroy(struct drm_fb *fb)
{
	if (fb->fb_id != 0)
		drmModeRmFB(fb->fd, fb->fb_id);
	weston_buffer_reference(&fb->buffer_ref, NULL);
	free(fb);
}

static void
drm_fb_destroy_dumb(struct drm_fb *fb)
{
	struct drm_mode_destroy_dumb destroy_arg;

	assert(fb->type == BUFFER_PIXMAN_DUMB);

	if (fb->map && fb->size > 0)
		munmap(fb->map, fb->size);

	memset(&destroy_arg, 0, sizeof(destroy_arg));
	destroy_arg.handle = fb->handle;
	drmIoctl(fb->fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy_arg);

	drm_fb_destroy(fb);
}

static void
drm_fb_destroy_gbm(struct gbm_bo *bo, void *data)
{
	struct drm_fb *fb = data;

	assert(fb->type == BUFFER_GBM_SURFACE || fb->type == BUFFER_CLIENT ||
	       fb->type == BUFFER_CURSOR);
	drm_fb_destroy(fb);
}

static struct drm_fb *
drm_fb_create_dumb(struct drm_backend *b, int width, int height,
		   uint32_t format)
{
	struct drm_fb *fb;
	int ret;

	struct drm_mode_create_dumb create_arg;
	struct drm_mode_destroy_dumb destroy_arg;
	struct drm_mode_map_dumb map_arg;

	fb = zalloc(sizeof *fb);
	if (!fb)
		return NULL;

	fb->refcnt = 1;

	fb->format = pixel_format_get_info(format);
	if (!fb->format) {
		weston_log("failed to look up format 0x%lx\n",
			   (unsigned long) format);
		goto err_fb;
	}

	if (!fb->format->depth || !fb->format->bpp) {
		weston_log("format 0x%lx is not compatible with dumb buffers\n",
			   (unsigned long) format);
		goto err_fb;
	}

	memset(&create_arg, 0, sizeof create_arg);
	create_arg.bpp = fb->format->bpp;
	create_arg.width = width;
	create_arg.height = height;

	ret = drmIoctl(b->drm.fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_arg);
	if (ret)
		goto err_fb;

	fb->type = BUFFER_PIXMAN_DUMB;
	fb->handle = create_arg.handle;
	fb->stride = create_arg.pitch;
	fb->size = create_arg.size;
	fb->width = width;
	fb->height = height;
	fb->fd = b->drm.fd;

	ret = -1;

	if (!b->no_addfb2) {
		uint32_t handles[4] = { 0 }, pitches[4] = { 0 }, offsets[4] = { 0 };

		handles[0] = fb->handle;
		pitches[0] = fb->stride;
		offsets[0] = 0;

		ret = drmModeAddFB2(b->drm.fd, width, height,
				    fb->format->format,
				    handles, pitches, offsets,
				    &fb->fb_id, 0);
		if (ret) {
			weston_log("addfb2 failed: %m\n");
			b->no_addfb2 = 1;
		}
	}

	if (ret) {
		ret = drmModeAddFB(b->drm.fd, width, height,
				   fb->format->depth, fb->format->bpp,
				   fb->stride, fb->handle, &fb->fb_id);
	}

	if (ret)
		goto err_bo;

	memset(&map_arg, 0, sizeof map_arg);
	map_arg.handle = fb->handle;
	ret = drmIoctl(fb->fd, DRM_IOCTL_MODE_MAP_DUMB, &map_arg);
	if (ret)
		goto err_add_fb;

	fb->map = mmap(NULL, fb->size, PROT_WRITE,
		       MAP_SHARED, b->drm.fd, map_arg.offset);
	if (fb->map == MAP_FAILED)
		goto err_add_fb;

	return fb;

err_add_fb:
	drmModeRmFB(b->drm.fd, fb->fb_id);
err_bo:
	memset(&destroy_arg, 0, sizeof(destroy_arg));
	destroy_arg.handle = create_arg.handle;
	drmIoctl(b->drm.fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy_arg);
err_fb:
	free(fb);
	return NULL;
}

static struct drm_fb *
drm_fb_ref(struct drm_fb *fb)
{
	fb->refcnt++;
	return fb;
}

static struct drm_fb *
drm_fb_get_from_bo(struct gbm_bo *bo, struct drm_backend *backend,
		   uint32_t format, enum drm_fb_type type)
{
	struct drm_fb *fb = gbm_bo_get_user_data(bo);
	uint32_t handles[4] = { 0 }, pitches[4] = { 0 }, offsets[4] = { 0 };
	int ret;

	if (fb) {
		assert(fb->type == type);
		return drm_fb_ref(fb);
	}

	fb = zalloc(sizeof *fb);
	if (fb == NULL)
		return NULL;

	fb->type = type;
	fb->refcnt = 1;
	fb->bo = bo;

	fb->width = gbm_bo_get_width(bo);
	fb->height = gbm_bo_get_height(bo);
	fb->stride = gbm_bo_get_stride(bo);
	fb->handle = gbm_bo_get_handle(bo).u32;
	fb->format = pixel_format_get_info(format);
	fb->size = fb->stride * fb->height;
	fb->fd = backend->drm.fd;

	if (!fb->format) {
		weston_log("couldn't look up format 0x%lx\n",
			   (unsigned long) format);
		goto err_free;
	}

	if (backend->min_width > fb->width ||
	    fb->width > backend->max_width ||
	    backend->min_height > fb->height ||
	    fb->height > backend->max_height) {
		weston_log("bo geometry out of bounds\n");
		goto err_free;
	}

	ret = -1;

	if (format && !backend->no_addfb2) {
		handles[0] = fb->handle;
		pitches[0] = fb->stride;
		offsets[0] = 0;

		ret = drmModeAddFB2(backend->drm.fd, fb->width, fb->height,
				    format, handles, pitches, offsets,
				    &fb->fb_id, 0);
		if (ret) {
			weston_log("addfb2 failed: %m\n");
			backend->no_addfb2 = 1;
			backend->sprites_are_broken = 1;
		}
	}

	if (ret && fb->format->depth && fb->format->bpp)
		ret = drmModeAddFB(backend->drm.fd, fb->width, fb->height,
				   fb->format->depth, fb->format->bpp,
				   fb->stride, fb->handle, &fb->fb_id);

	if (ret) {
		weston_log("failed to create kms fb: %m\n");
		goto err_free;
	}

	gbm_bo_set_user_data(bo, fb, drm_fb_destroy_gbm);

	return fb;

err_free:
	free(fb);
	return NULL;
}

static void
drm_fb_set_buffer(struct drm_fb *fb, struct weston_buffer *buffer)
{
	assert(fb->buffer_ref.buffer == NULL);
	assert(fb->type == BUFFER_CLIENT);
	weston_buffer_reference(&fb->buffer_ref, buffer);
}

static void
drm_fb_unref(struct drm_fb *fb)
{
	if (!fb)
		return;

	assert(fb->refcnt > 0);
	if (--fb->refcnt > 0)
		return;

	switch (fb->type) {
	case BUFFER_PIXMAN_DUMB:
		drm_fb_destroy_dumb(fb);
		break;
	case BUFFER_CURSOR:
	case BUFFER_CLIENT:
		gbm_bo_destroy(fb->bo);
		break;
	case BUFFER_GBM_SURFACE:
		gbm_surface_release_buffer(fb->gbm_surface, fb->bo);
		break;
	default:
		assert(NULL);
		break;
	}
}

static int
drm_view_transform_supported(struct weston_view *ev)
{
	return !ev->transform.enabled ||
		(ev->transform.matrix.type < WESTON_MATRIX_TRANSFORM_ROTATE);
}

/**
 * Allocate a new drm_pending_state
 *
 * Allocate a new, empty, 'pending state' structure to be used across a
 * repaint cycle or similar.
 *
 * @param backend DRM backend
 * @returns Newly-allocated pending state structure
 */
static struct drm_pending_state *
drm_pending_state_alloc(struct drm_backend *backend)
{
	struct drm_pending_state *ret;

	ret = calloc(1, sizeof(*ret));
	if (!ret)
		return NULL;

	ret->backend = backend;

	return ret;
}

/**
 * Free a drm_pending_state structure
 *
 * Frees a pending_state structure.
 *
 * @param pending_state Pending state structure to free
 */
static void
drm_pending_state_free(struct drm_pending_state *pending_state)
{
	if (!pending_state)
		return;

	free(pending_state);
}

static uint32_t
drm_output_check_scanout_format(struct drm_output *output,
				struct weston_surface *es, struct gbm_bo *bo)
{
	uint32_t format;
	pixman_region32_t r;

	format = gbm_bo_get_format(bo);

	if (format == GBM_FORMAT_ARGB8888) {
		/* We can scanout an ARGB buffer if the surface's
		 * opaque region covers the whole output, but we have
		 * to use XRGB as the KMS format code. */
		pixman_region32_init_rect(&r, 0, 0,
					  output->base.width,
					  output->base.height);
		pixman_region32_subtract(&r, &r, &es->opaque);

		if (!pixman_region32_not_empty(&r))
			format = GBM_FORMAT_XRGB8888;

		pixman_region32_fini(&r);
	}

	if (output->gbm_format == format)
		return format;

	return 0;
}

static struct weston_plane *
drm_output_prepare_scanout_view(struct drm_output *output,
				struct weston_view *ev)
{
	struct drm_backend *b = to_drm_backend(output->base.compositor);
	struct weston_buffer *buffer = ev->surface->buffer_ref.buffer;
	struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
	struct gbm_bo *bo;
	uint32_t format;

	/* Don't import buffers which span multiple outputs. */
	if (ev->output_mask != (1u << output->base.id))
		return NULL;

	/* We use GBM to import buffers. */
	if (b->gbm == NULL)
		return NULL;

	if (buffer == NULL)
		return NULL;
	if (wl_shm_buffer_get(buffer->resource))
		return NULL;

	/* Make sure our view is exactly compatible with the output. */
	if (ev->geometry.x != output->base.x ||
	    ev->geometry.y != output->base.y)
		return NULL;
	if (buffer->width != output->base.current_mode->width ||
	    buffer->height != output->base.current_mode->height)
		return NULL;

	if (ev->transform.enabled)
		return NULL;
	if (ev->geometry.scissor_enabled)
		return NULL;
	if (viewport->buffer.transform != output->base.transform)
		return NULL;
	if (viewport->buffer.scale != output->base.current_scale)
		return NULL;
	if (!drm_view_transform_supported(ev))
		return NULL;

	if (ev->alpha != 1.0f)
		return NULL;

	bo = gbm_bo_import(b->gbm, GBM_BO_IMPORT_WL_BUFFER,
			   buffer->resource, GBM_BO_USE_SCANOUT);

	/* Unable to use the buffer for scanout */
	if (!bo)
		return NULL;

	format = drm_output_check_scanout_format(output, ev->surface, bo);
	if (format == 0) {
		gbm_bo_destroy(bo);
		return NULL;
	}

	output->fb_pending = drm_fb_get_from_bo(bo, b, format, BUFFER_CLIENT);
	if (!output->fb_pending) {
		gbm_bo_destroy(bo);
		return NULL;
	}

	drm_fb_set_buffer(output->fb_pending, buffer);

	return &output->scanout_plane;
}

static struct drm_fb *
drm_output_render_gl(struct drm_output *output, pixman_region32_t *damage)
{
	struct drm_backend *b = to_drm_backend(output->base.compositor);
	struct gbm_bo *bo;
	struct drm_fb *ret;

	output->base.compositor->renderer->repaint_output(&output->base,
							  damage);

	bo = gbm_surface_lock_front_buffer(output->gbm_surface);
	if (!bo) {
		weston_log("failed to lock front buffer: %m\n");
		return NULL;
	}

	ret = drm_fb_get_from_bo(bo, b, output->gbm_format, BUFFER_GBM_SURFACE);
	if (!ret) {
		weston_log("failed to get drm_fb for bo\n");
		gbm_surface_release_buffer(output->gbm_surface, bo);
		return NULL;
	}
	ret->gbm_surface = output->gbm_surface;

	return ret;
}

static struct drm_fb *
drm_output_render_pixman(struct drm_output *output, pixman_region32_t *damage)
{
	struct weston_compositor *ec = output->base.compositor;
	pixman_region32_t total_damage, previous_damage;

	pixman_region32_init(&total_damage);
	pixman_region32_init(&previous_damage);

	pixman_region32_copy(&previous_damage, damage);

	pixman_region32_union(&total_damage, damage, &output->previous_damage);
	pixman_region32_copy(&output->previous_damage, &previous_damage);

	output->current_image ^= 1;

	pixman_renderer_output_set_buffer(&output->base,
					  output->image[output->current_image]);

	ec->renderer->repaint_output(&output->base, &total_damage);

	pixman_region32_fini(&total_damage);
	pixman_region32_fini(&previous_damage);

	return drm_fb_ref(output->dumb[output->current_image]);
}

static void
drm_output_render(struct drm_output *output, pixman_region32_t *damage)
{
	struct weston_compositor *c = output->base.compositor;
	struct drm_backend *b = to_drm_backend(c);
	struct drm_fb *fb;

	/* If we already have a client buffer promoted to scanout, then we don't
	 * want to render. */
	if (output->fb_pending)
		return;

	if (b->use_pixman)
		fb = drm_output_render_pixman(output, damage);
	else
		fb = drm_output_render_gl(output, damage);

	if (!fb)
		return;
	output->fb_pending = fb;

	pixman_region32_subtract(&c->primary_plane.damage,
				 &c->primary_plane.damage, damage);
}

static void
drm_output_set_gamma(struct weston_output *output_base,
		     uint16_t size, uint16_t *r, uint16_t *g, uint16_t *b)
{
	int rc;
	struct drm_output *output = to_drm_output(output_base);
	struct drm_backend *backend =
		to_drm_backend(output->base.compositor);

	/* check */
	if (output_base->gamma_size != size)
		return;
	if (!output->original_crtc)
		return;

	rc = drmModeCrtcSetGamma(backend->drm.fd,
				 output->crtc_id,
				 size, r, g, b);
	if (rc)
		weston_log("set gamma failed: %m\n");
}

/* Determine the type of vblank synchronization to use for the output.
 *
 * The pipe parameter indicates which CRTC is in use.  Knowing this, we
 * can determine which vblank sequence type to use for it.  Traditional
 * cards had only two CRTCs, with CRTC 0 using no special flags, and
 * CRTC 1 using DRM_VBLANK_SECONDARY.  The first bit of the pipe
 * parameter indicates this.
 *
 * Bits 1-5 of the pipe parameter are 5 bit wide pipe number between
 * 0-31.  If this is non-zero it indicates we're dealing with a
 * multi-gpu situation and we need to calculate the vblank sync
 * using DRM_BLANK_HIGH_CRTC_MASK.
 */
static unsigned int
drm_waitvblank_pipe(struct drm_output *output)
{
	if (output->pipe > 1)
		return (output->pipe << DRM_VBLANK_HIGH_CRTC_SHIFT) &
				DRM_VBLANK_HIGH_CRTC_MASK;
	else if (output->pipe > 0)
		return DRM_VBLANK_SECONDARY;
	else
		return 0;
}

static int
drm_output_repaint(struct weston_output *output_base,
		   pixman_region32_t *damage,
		   void *repaint_data)
{
	struct drm_output *output = to_drm_output(output_base);
	struct drm_backend *backend =
		to_drm_backend(output->base.compositor);
	struct drm_plane *p;
	struct drm_mode *mode;
	int ret = 0;

	if (output->disable_pending || output->destroy_pending)
		return -1;

	assert(!output->fb_last);

	/* If disable_planes is set then assign_planes() wasn't
	 * called for this render, so we could still have a stale
	 * cursor plane set up.
	 */
	if (output->base.disable_planes) {
		output->cursor_view = NULL;
		output->cursor_plane.x = INT32_MIN;
		output->cursor_plane.y = INT32_MIN;
	}

	drm_output_render(output, damage);
	if (!output->fb_pending)
		return -1;

	mode = container_of(output->base.current_mode, struct drm_mode, base);
	if (output->state_invalid || !output->fb_current ||
	    output->fb_current->stride != output->fb_pending->stride) {
		ret = drmModeSetCrtc(backend->drm.fd, output->crtc_id,
				     output->fb_pending->fb_id, 0, 0,
				     &output->connector_id, 1,
				     &mode->mode_info);
		if (ret) {
			weston_log("set mode failed: %m\n");
			goto err_pageflip;
		}
		output_base->set_dpms(output_base, WESTON_DPMS_ON);

		output->state_invalid = false;
	}

	if (drmModePageFlip(backend->drm.fd, output->crtc_id,
			    output->fb_pending->fb_id,
			    DRM_MODE_PAGE_FLIP_EVENT, output) < 0) {
		weston_log("queueing pageflip failed: %m\n");
		goto err_pageflip;
	}

	output->fb_last = output->fb_current;
	output->fb_current = output->fb_pending;
	output->fb_pending = NULL;

	assert(!output->page_flip_pending);
	output->page_flip_pending = 1;

	if (output->pageflip_timer)
		wl_event_source_timer_update(output->pageflip_timer,
		                             backend->pageflip_timeout);

	drm_output_set_cursor(output);

	/*
	 * Now, update all the sprite surfaces
	 */
	wl_list_for_each(p, &backend->plane_list, link) {
		uint32_t flags = 0, fb_id = 0;
		drmVBlank vbl = {
			.request.type = DRM_VBLANK_RELATIVE | DRM_VBLANK_EVENT,
			.request.sequence = 1,
		};

		if (p->type != WDRM_PLANE_TYPE_OVERLAY)
			continue;

		if ((!p->fb_current && !p->fb_pending) ||
		    !drm_plane_crtc_supported(output, p))
			continue;

		if (p->fb_pending && !backend->sprites_hidden)
			fb_id = p->fb_pending->fb_id;

		ret = drmModeSetPlane(backend->drm.fd, p->plane_id,
				      output->crtc_id, fb_id, flags,
				      p->dest_x, p->dest_y,
				      p->dest_w, p->dest_h,
				      p->src_x, p->src_y,
				      p->src_w, p->src_h);
		if (ret)
			weston_log("setplane failed: %d: %s\n",
				ret, strerror(errno));

		vbl.request.type |= drm_waitvblank_pipe(output);

		/*
		 * Queue a vblank signal so we know when the surface
		 * becomes active on the display or has been replaced.
		 */
		vbl.request.signal = (unsigned long) p;
		ret = drmWaitVBlank(backend->drm.fd, &vbl);
		if (ret) {
			weston_log("vblank event request failed: %d: %s\n",
				ret, strerror(errno));
		}

		p->output = output;
		p->fb_last = p->fb_current;
		p->fb_current = p->fb_pending;
		p->fb_pending = NULL;
		output->vblank_pending++;
	}

	return 0;

err_pageflip:
	output->cursor_view = NULL;
	if (output->fb_pending) {
		drm_fb_unref(output->fb_pending);
		output->fb_pending = NULL;
	}

	return -1;
}

static void
drm_output_start_repaint_loop(struct weston_output *output_base)
{
	struct drm_output *output = to_drm_output(output_base);
	struct drm_backend *backend =
		to_drm_backend(output_base->compositor);
	uint32_t fb_id;
	struct timespec ts, tnow;
	struct timespec vbl2now;
	int64_t refresh_nsec;
	int ret;
	drmVBlank vbl = {
		.request.type = DRM_VBLANK_RELATIVE,
		.request.sequence = 0,
		.request.signal = 0,
	};

	if (output->disable_pending || output->destroy_pending)
		return;

	if (!output->fb_current) {
		/* We can't page flip if there's no mode set */
		goto finish_frame;
	}

	/* Need to smash all state in from scratch; current timings might not
	 * be what we want, page flip might not work, etc.
	 */
	if (output->state_invalid)
		goto finish_frame;

	/* Try to get current msc and timestamp via instant query */
	vbl.request.type |= drm_waitvblank_pipe(output);
	ret = drmWaitVBlank(backend->drm.fd, &vbl);

	/* Error ret or zero timestamp means failure to get valid timestamp */
	if ((ret == 0) && (vbl.reply.tval_sec > 0 || vbl.reply.tval_usec > 0)) {
		ts.tv_sec = vbl.reply.tval_sec;
		ts.tv_nsec = vbl.reply.tval_usec * 1000;

		/* Valid timestamp for most recent vblank - not stale?
		 * Stale ts could happen on Linux 3.17+, so make sure it
		 * is not older than 1 refresh duration since now.
		 */
		weston_compositor_read_presentation_clock(backend->compositor,
							  &tnow);
		timespec_sub(&vbl2now, &tnow, &ts);
		refresh_nsec =
			millihz_to_nsec(output->base.current_mode->refresh);
		if (timespec_to_nsec(&vbl2now) < refresh_nsec) {
			drm_output_update_msc(output, vbl.reply.sequence);
			weston_output_finish_frame(output_base, &ts,
						WP_PRESENTATION_FEEDBACK_INVALID);
			return;
		}
	}

	/* Immediate query didn't provide valid timestamp.
	 * Use pageflip fallback.
	 */
	fb_id = output->fb_current->fb_id;

	assert(!output->page_flip_pending);
	assert(!output->fb_last);

	if (drmModePageFlip(backend->drm.fd, output->crtc_id, fb_id,
			    DRM_MODE_PAGE_FLIP_EVENT, output) < 0) {
		weston_log("queueing pageflip failed: %m\n");
		goto finish_frame;
	}

	if (output->pageflip_timer)
		wl_event_source_timer_update(output->pageflip_timer,
		                             backend->pageflip_timeout);

	output->fb_last = drm_fb_ref(output->fb_current);
	output->page_flip_pending = 1;

	return;

finish_frame:
	/* if we cannot page-flip, immediately finish frame */
	weston_output_finish_frame(output_base, NULL,
				   WP_PRESENTATION_FEEDBACK_INVALID);
}

static void
drm_output_update_msc(struct drm_output *output, unsigned int seq)
{
	uint64_t msc_hi = output->base.msc >> 32;

	if (seq < (output->base.msc & 0xffffffff))
		msc_hi++;

	output->base.msc = (msc_hi << 32) + seq;
}

static void
vblank_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec,
	       void *data)
{
	struct drm_plane *s = (struct drm_plane *)data;
	struct drm_output *output = s->output;
	struct timespec ts;
	uint32_t flags = WP_PRESENTATION_FEEDBACK_KIND_HW_COMPLETION |
			 WP_PRESENTATION_FEEDBACK_KIND_HW_CLOCK;

	drm_output_update_msc(output, frame);
	output->vblank_pending--;
	assert(output->vblank_pending >= 0);

	assert(s->fb_last || s->fb_current);
	drm_fb_unref(s->fb_last);
	s->fb_last = NULL;

	if (!output->page_flip_pending && !output->vblank_pending) {
		/* Stop the pageflip timer instead of rearming it here */
		if (output->pageflip_timer)
			wl_event_source_timer_update(output->pageflip_timer, 0);

		ts.tv_sec = sec;
		ts.tv_nsec = usec * 1000;
		weston_output_finish_frame(&output->base, &ts, flags);
	}
}

static void
drm_output_destroy(struct weston_output *base);

static void
page_flip_handler(int fd, unsigned int frame,
		  unsigned int sec, unsigned int usec, void *data)
{
	struct drm_output *output = data;
	struct timespec ts;
	uint32_t flags = WP_PRESENTATION_FEEDBACK_KIND_VSYNC |
			 WP_PRESENTATION_FEEDBACK_KIND_HW_COMPLETION |
			 WP_PRESENTATION_FEEDBACK_KIND_HW_CLOCK;

	drm_output_update_msc(output, frame);

	assert(output->page_flip_pending);
	output->page_flip_pending = 0;

	drm_fb_unref(output->fb_last);
	output->fb_last = NULL;

	if (output->destroy_pending)
		drm_output_destroy(&output->base);
	else if (output->disable_pending)
		weston_output_disable(&output->base);
	else if (!output->vblank_pending) {
		/* Stop the pageflip timer instead of rearming it here */
		if (output->pageflip_timer)
			wl_event_source_timer_update(output->pageflip_timer, 0);

		ts.tv_sec = sec;
		ts.tv_nsec = usec * 1000;
		weston_output_finish_frame(&output->base, &ts, flags);

		/* We can't call this from frame_notify, because the output's
		 * repaint needed flag is cleared just after that */
		if (output->recorder)
			weston_output_schedule_repaint(&output->base);
	}
}

/**
 * Begin a new repaint cycle
 *
 * Called by the core compositor at the beginning of a repaint cycle.
 */
static void *
drm_repaint_begin(struct weston_compositor *compositor)
{
	struct drm_backend *b = to_drm_backend(compositor);
	struct drm_pending_state *ret;

	ret = drm_pending_state_alloc(b);
	b->repaint_data = ret;

	return ret;
}

/**
 * Flush a repaint set
 *
 * Called by the core compositor when a repaint cycle has been completed
 * and should be flushed.
 */
static void
drm_repaint_flush(struct weston_compositor *compositor, void *repaint_data)
{
	struct drm_backend *b = to_drm_backend(compositor);
	struct drm_pending_state *pending_state = repaint_data;

	drm_pending_state_free(pending_state);
	b->repaint_data = NULL;
}

/**
 * Cancel a repaint set
 *
 * Called by the core compositor when a repaint has finished, so the data
 * held across the repaint cycle should be discarded.
 */
static void
drm_repaint_cancel(struct weston_compositor *compositor, void *repaint_data)
{
	struct drm_backend *b = to_drm_backend(compositor);
	struct drm_pending_state *pending_state = repaint_data;

	drm_pending_state_free(pending_state);
	b->repaint_data = NULL;
}

static uint32_t
drm_output_check_plane_format(struct drm_plane *p,
			       struct weston_view *ev, struct gbm_bo *bo)
{
	uint32_t i, format;

	format = gbm_bo_get_format(bo);

	if (format == GBM_FORMAT_ARGB8888) {
		pixman_region32_t r;

		pixman_region32_init_rect(&r, 0, 0,
					  ev->surface->width,
					  ev->surface->height);
		pixman_region32_subtract(&r, &r, &ev->surface->opaque);

		if (!pixman_region32_not_empty(&r))
			format = GBM_FORMAT_XRGB8888;

		pixman_region32_fini(&r);
	}

	for (i = 0; i < p->count_formats; i++)
		if (p->formats[i] == format)
			return format;

	return 0;
}

static struct weston_plane *
drm_output_prepare_overlay_view(struct drm_output *output,
				struct weston_view *ev)
{
	struct weston_compositor *ec = output->base.compositor;
	struct drm_backend *b = to_drm_backend(ec);
	struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
	struct wl_resource *buffer_resource;
	struct drm_plane *p;
	struct linux_dmabuf_buffer *dmabuf;
	int found = 0;
	struct gbm_bo *bo;
	pixman_region32_t dest_rect, src_rect;
	pixman_box32_t *box, tbox;
	uint32_t format;
	wl_fixed_t sx1, sy1, sx2, sy2;

	if (b->sprites_are_broken)
		return NULL;

	/* Don't import buffers which span multiple outputs. */
	if (ev->output_mask != (1u << output->base.id))
		return NULL;

	/* We can only import GBM buffers. */
	if (b->gbm == NULL)
		return NULL;

	if (ev->surface->buffer_ref.buffer == NULL)
		return NULL;
	buffer_resource = ev->surface->buffer_ref.buffer->resource;
	if (wl_shm_buffer_get(buffer_resource))
		return NULL;

	if (viewport->buffer.transform != output->base.transform)
		return NULL;
	if (viewport->buffer.scale != output->base.current_scale)
		return NULL;
	if (!drm_view_transform_supported(ev))
		return NULL;

	if (ev->alpha != 1.0f)
		return NULL;

	wl_list_for_each(p, &b->plane_list, link) {
		if (p->type != WDRM_PLANE_TYPE_OVERLAY)
			continue;

		if (!drm_plane_crtc_supported(output, p))
			continue;

		if (!p->fb_pending) {
			found = 1;
			break;
		}
	}

	/* No sprites available */
	if (!found)
		return NULL;

	if ((dmabuf = linux_dmabuf_buffer_get(buffer_resource))) {
#ifdef HAVE_GBM_FD_IMPORT
		/* XXX: TODO:
		 *
		 * Use AddFB2 directly, do not go via GBM.
		 * Add support for multiplanar formats.
		 * Both require refactoring in the DRM-backend to
		 * support a mix of gbm_bos and drmfbs.
		 */
		struct gbm_import_fd_data gbm_dmabuf = {
			.fd     = dmabuf->attributes.fd[0],
			.width  = dmabuf->attributes.width,
			.height = dmabuf->attributes.height,
			.stride = dmabuf->attributes.stride[0],
			.format = dmabuf->attributes.format
		};

                /* XXX: TODO:
                 *
                 * Currently the buffer is rejected if any dmabuf attribute
                 * flag is set.  This keeps us from passing an inverted /
                 * interlaced / bottom-first buffer (or any other type that may
                 * be added in the future) through to an overlay.  Ultimately,
                 * these types of buffers should be handled through buffer
                 * transforms and not as spot-checks requiring specific
                 * knowledge. */
		if (dmabuf->attributes.n_planes != 1 ||
                    dmabuf->attributes.offset[0] != 0 ||
		    dmabuf->attributes.flags)
			return NULL;

		bo = gbm_bo_import(b->gbm, GBM_BO_IMPORT_FD, &gbm_dmabuf,
				   GBM_BO_USE_SCANOUT);
#else
		return NULL;
#endif
	} else {
		bo = gbm_bo_import(b->gbm, GBM_BO_IMPORT_WL_BUFFER,
				   buffer_resource, GBM_BO_USE_SCANOUT);
	}
	if (!bo)
		return NULL;

	format = drm_output_check_plane_format(p, ev, bo);
	if (format == 0) {
		gbm_bo_destroy(bo);
		return NULL;
	}

	p->fb_pending = drm_fb_get_from_bo(bo, b, format, BUFFER_CLIENT);
	if (!p->fb_pending) {
		gbm_bo_destroy(bo);
		return NULL;
	}

	drm_fb_set_buffer(p->fb_pending, ev->surface->buffer_ref.buffer);

	box = pixman_region32_extents(&ev->transform.boundingbox);
	p->base.x = box->x1;
	p->base.y = box->y1;

	/*
	 * Calculate the source & dest rects properly based on actual
	 * position (note the caller has called weston_view_update_transform()
	 * for us already).
	 */
	pixman_region32_init(&dest_rect);
	pixman_region32_intersect(&dest_rect, &ev->transform.boundingbox,
				  &output->base.region);
	pixman_region32_translate(&dest_rect, -output->base.x, -output->base.y);
	box = pixman_region32_extents(&dest_rect);
	tbox = weston_transformed_rect(output->base.width,
				       output->base.height,
				       output->base.transform,
				       output->base.current_scale,
				       *box);
	p->dest_x = tbox.x1;
	p->dest_y = tbox.y1;
	p->dest_w = tbox.x2 - tbox.x1;
	p->dest_h = tbox.y2 - tbox.y1;
	pixman_region32_fini(&dest_rect);

	pixman_region32_init(&src_rect);
	pixman_region32_intersect(&src_rect, &ev->transform.boundingbox,
				  &output->base.region);
	box = pixman_region32_extents(&src_rect);

	weston_view_from_global_fixed(ev,
				      wl_fixed_from_int(box->x1),
				      wl_fixed_from_int(box->y1),
				      &sx1, &sy1);
	weston_view_from_global_fixed(ev,
				      wl_fixed_from_int(box->x2),
				      wl_fixed_from_int(box->y2),
				      &sx2, &sy2);

	if (sx1 < 0)
		sx1 = 0;
	if (sy1 < 0)
		sy1 = 0;
	if (sx2 > wl_fixed_from_int(ev->surface->width))
		sx2 = wl_fixed_from_int(ev->surface->width);
	if (sy2 > wl_fixed_from_int(ev->surface->height))
		sy2 = wl_fixed_from_int(ev->surface->height);

	tbox.x1 = sx1;
	tbox.y1 = sy1;
	tbox.x2 = sx2;
	tbox.y2 = sy2;

	tbox = weston_transformed_rect(wl_fixed_from_int(ev->surface->width),
				       wl_fixed_from_int(ev->surface->height),
				       viewport->buffer.transform,
				       viewport->buffer.scale,
				       tbox);

	p->src_x = tbox.x1 << 8;
	p->src_y = tbox.y1 << 8;
	p->src_w = (tbox.x2 - tbox.x1) << 8;
	p->src_h = (tbox.y2 - tbox.y1) << 8;
	pixman_region32_fini(&src_rect);

	return &p->base;
}

static struct weston_plane *
drm_output_prepare_cursor_view(struct drm_output *output,
			       struct weston_view *ev)
{
	struct drm_backend *b = to_drm_backend(output->base.compositor);
	struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
	struct wl_shm_buffer *shmbuf;
	float x, y;

	if (b->cursors_are_broken)
		return NULL;

	if (output->cursor_view)
		return NULL;

	/* Don't import buffers which span multiple outputs. */
	if (ev->output_mask != (1u << output->base.id))
		return NULL;

	/* We use GBM to import SHM buffers. */
	if (b->gbm == NULL)
		return NULL;

	if (ev->surface->buffer_ref.buffer == NULL)
		return NULL;
	shmbuf = wl_shm_buffer_get(ev->surface->buffer_ref.buffer->resource);
	if (!shmbuf)
		return NULL;
	if (wl_shm_buffer_get_format(shmbuf) != WL_SHM_FORMAT_ARGB8888)
		return NULL;

	if (output->base.transform != WL_OUTPUT_TRANSFORM_NORMAL)
		return NULL;
	if (ev->transform.enabled &&
	    (ev->transform.matrix.type > WESTON_MATRIX_TRANSFORM_TRANSLATE))
		return NULL;
	if (viewport->buffer.scale != output->base.current_scale)
		return NULL;
	if (ev->geometry.scissor_enabled)
		return NULL;

	if (ev->surface->width > b->cursor_width ||
	    ev->surface->height > b->cursor_height)
		return NULL;

	output->cursor_view = ev;
	weston_view_to_global_float(ev, 0, 0, &x, &y);
	output->cursor_plane.x = x;
	output->cursor_plane.y = y;

	return &output->cursor_plane;
}

/**
 * Update the image for the current cursor surface
 *
 * @param b DRM backend structure
 * @param bo GBM buffer object to write into
 * @param ev View to use for cursor image
 */
static void
cursor_bo_update(struct drm_backend *b, struct gbm_bo *bo,
		 struct weston_view *ev)
{
	struct weston_buffer *buffer = ev->surface->buffer_ref.buffer;
	uint32_t buf[b->cursor_width * b->cursor_height];
	int32_t stride;
	uint8_t *s;
	int i;

	assert(buffer && buffer->shm_buffer);
	assert(buffer->shm_buffer == wl_shm_buffer_get(buffer->resource));
	assert(ev->surface->width <= b->cursor_width);
	assert(ev->surface->height <= b->cursor_height);

	memset(buf, 0, sizeof buf);
	stride = wl_shm_buffer_get_stride(buffer->shm_buffer);
	s = wl_shm_buffer_get_data(buffer->shm_buffer);

	wl_shm_buffer_begin_access(buffer->shm_buffer);
	for (i = 0; i < ev->surface->height; i++)
		memcpy(buf + i * b->cursor_width,
		       s + i * stride,
		       ev->surface->width * 4);
	wl_shm_buffer_end_access(buffer->shm_buffer);

	if (gbm_bo_write(bo, buf, sizeof buf) < 0)
		weston_log("failed update cursor: %m\n");
}

static void
drm_output_set_cursor(struct drm_output *output)
{
	struct weston_view *ev = output->cursor_view;
	struct drm_backend *b = to_drm_backend(output->base.compositor);
	EGLint handle;
	struct gbm_bo *bo;
	float x, y;

	if (ev == NULL) {
		drmModeSetCursor(b->drm.fd, output->crtc_id, 0, 0, 0);
		return;
	}

	if (pixman_region32_not_empty(&output->cursor_plane.damage)) {
		pixman_region32_fini(&output->cursor_plane.damage);
		pixman_region32_init(&output->cursor_plane.damage);
		output->current_cursor ^= 1;
		bo = output->gbm_cursor_fb[output->current_cursor]->bo;

		cursor_bo_update(b, bo, ev);
		handle = gbm_bo_get_handle(bo).s32;
		if (drmModeSetCursor(b->drm.fd, output->crtc_id, handle,
				b->cursor_width, b->cursor_height)) {
			weston_log("failed to set cursor: %m\n");
			b->cursors_are_broken = 1;
		}
	}

	x = (output->cursor_plane.x - output->base.x) *
		output->base.current_scale;
	y = (output->cursor_plane.y - output->base.y) *
		output->base.current_scale;

	if (drmModeMoveCursor(b->drm.fd, output->crtc_id, x, y)) {
		weston_log("failed to move cursor: %m\n");
		b->cursors_are_broken = 1;
	}
}

static void
drm_assign_planes(struct weston_output *output_base, void *repaint_data)
{
	struct drm_backend *b = to_drm_backend(output_base->compositor);
	struct drm_output *output = to_drm_output(output_base);
	struct weston_view *ev, *next;
	pixman_region32_t overlap, surface_overlap;
	struct weston_plane *primary, *next_plane;

	/*
	 * Find a surface for each sprite in the output using some heuristics:
	 * 1) size
	 * 2) frequency of update
	 * 3) opacity (though some hw might support alpha blending)
	 * 4) clipping (this can be fixed with color keys)
	 *
	 * The idea is to save on blitting since this should save power.
	 * If we can get a large video surface on the sprite for example,
	 * the main display surface may not need to update at all, and
	 * the client buffer can be used directly for the sprite surface
	 * as we do for flipping full screen surfaces.
	 */
	pixman_region32_init(&overlap);
	primary = &output_base->compositor->primary_plane;

	output->cursor_view = NULL;
	output->cursor_plane.x = INT32_MIN;
	output->cursor_plane.y = INT32_MIN;

	wl_list_for_each_safe(ev, next, &output_base->compositor->view_list, link) {
		struct weston_surface *es = ev->surface;

		/* Test whether this buffer can ever go into a plane:
		 * non-shm, or small enough to be a cursor.
		 *
		 * Also, keep a reference when using the pixman renderer.
		 * That makes it possible to do a seamless switch to the GL
		 * renderer and since the pixman renderer keeps a reference
		 * to the buffer anyway, there is no side effects.
		 */
		if (b->use_pixman ||
		    (es->buffer_ref.buffer &&
		    (!wl_shm_buffer_get(es->buffer_ref.buffer->resource) ||
		     (ev->surface->width <= b->cursor_width &&
		      ev->surface->height <= b->cursor_height))))
			es->keep_buffer = true;
		else
			es->keep_buffer = false;

		pixman_region32_init(&surface_overlap);
		pixman_region32_intersect(&surface_overlap, &overlap,
					  &ev->transform.boundingbox);

		next_plane = NULL;
		if (pixman_region32_not_empty(&surface_overlap))
			next_plane = primary;
		if (next_plane == NULL)
			next_plane = drm_output_prepare_cursor_view(output, ev);
		if (next_plane == NULL)
			next_plane = drm_output_prepare_scanout_view(output, ev);
		if (next_plane == NULL)
			next_plane = drm_output_prepare_overlay_view(output, ev);
		if (next_plane == NULL)
			next_plane = primary;

		weston_view_move_to_plane(ev, next_plane);

		if (next_plane == primary)
			pixman_region32_union(&overlap, &overlap,
					      &ev->transform.boundingbox);

		if (next_plane == primary ||
		    next_plane == &output->cursor_plane) {
			/* cursor plane involves a copy */
			ev->psf_flags = 0;
		} else {
			/* All other planes are a direct scanout of a
			 * single client buffer.
			 */
			ev->psf_flags = WP_PRESENTATION_FEEDBACK_KIND_ZERO_COPY;
		}

		pixman_region32_fini(&surface_overlap);
	}
	pixman_region32_fini(&overlap);
}

/**
 * Find the closest-matching mode for a given target
 *
 * Given a target mode, find the most suitable mode amongst the output's
 * current mode list to use, preferring the current mode if possible, to
 * avoid an expensive mode switch.
 *
 * @param output DRM output
 * @param target_mode Mode to attempt to match
 * @returns Pointer to a mode from the output's mode list
 */
static struct drm_mode *
choose_mode (struct drm_output *output, struct weston_mode *target_mode)
{
	struct drm_mode *tmp_mode = NULL, *mode;

	if (output->base.current_mode->width == target_mode->width &&
	    output->base.current_mode->height == target_mode->height &&
	    (output->base.current_mode->refresh == target_mode->refresh ||
	     target_mode->refresh == 0))
		return (struct drm_mode *)output->base.current_mode;

	wl_list_for_each(mode, &output->base.mode_list, base.link) {
		if (mode->mode_info.hdisplay == target_mode->width &&
		    mode->mode_info.vdisplay == target_mode->height) {
			if (mode->base.refresh == target_mode->refresh ||
			    target_mode->refresh == 0) {
				return mode;
			} else if (!tmp_mode)
				tmp_mode = mode;
		}
	}

	return tmp_mode;
}

static int
drm_output_init_egl(struct drm_output *output, struct drm_backend *b);
static void
drm_output_fini_egl(struct drm_output *output);
static int
drm_output_init_pixman(struct drm_output *output, struct drm_backend *b);
static void
drm_output_fini_pixman(struct drm_output *output);

static int
drm_output_switch_mode(struct weston_output *output_base, struct weston_mode *mode)
{
	struct drm_output *output;
	struct drm_mode *drm_mode;
	struct drm_backend *b;

	if (output_base == NULL) {
		weston_log("output is NULL.\n");
		return -1;
	}

	if (mode == NULL) {
		weston_log("mode is NULL.\n");
		return -1;
	}

	b = to_drm_backend(output_base->compositor);
	output = to_drm_output(output_base);
	drm_mode  = choose_mode (output, mode);

	if (!drm_mode) {
		weston_log("%s, invalid resolution:%dx%d\n", __func__, mode->width, mode->height);
		return -1;
	}

	if (&drm_mode->base == output->base.current_mode)
		return 0;

	output->base.current_mode->flags = 0;

	output->base.current_mode = &drm_mode->base;
	output->base.current_mode->flags =
		WL_OUTPUT_MODE_CURRENT | WL_OUTPUT_MODE_PREFERRED;

	/* XXX: This drops our current buffer too early, before we've started
	 *      displaying it. Ideally this should be much more atomic and
	 *      integrated with a full repaint cycle, rather than doing a
	 *      sledgehammer modeswitch first, and only later showing new
	 *      content.
	 */
	drm_fb_unref(output->fb_current);
	assert(!output->fb_last);
	assert(!output->fb_pending);
	output->fb_last = output->fb_current = NULL;

	if (b->use_pixman) {
		drm_output_fini_pixman(output);
		if (drm_output_init_pixman(output, b) < 0) {
			weston_log("failed to init output pixman state with "
				   "new mode\n");
			return -1;
		}
	} else {
		drm_output_fini_egl(output);
		if (drm_output_init_egl(output, b) < 0) {
			weston_log("failed to init output egl state with "
				   "new mode");
			return -1;
		}
	}

	return 0;
}

static int
on_drm_input(int fd, uint32_t mask, void *data)
{
	drmEventContext evctx;

	memset(&evctx, 0, sizeof evctx);
	evctx.version = 2;
	evctx.page_flip_handler = page_flip_handler;
	evctx.vblank_handler = vblank_handler;
	drmHandleEvent(fd, &evctx);

	return 1;
}

static int
init_kms_caps(struct drm_backend *b)
{
	uint64_t cap;
	int ret;
	clockid_t clk_id;

	weston_log("using %s\n", b->drm.filename);

	ret = drmGetCap(b->drm.fd, DRM_CAP_TIMESTAMP_MONOTONIC, &cap);
	if (ret == 0 && cap == 1)
		clk_id = CLOCK_MONOTONIC;
	else
		clk_id = CLOCK_REALTIME;

	if (weston_compositor_set_presentation_clock(b->compositor, clk_id) < 0) {
		weston_log("Error: failed to set presentation clock %d.\n",
			   clk_id);
		return -1;
	}

	ret = drmGetCap(b->drm.fd, DRM_CAP_CURSOR_WIDTH, &cap);
	if (ret == 0)
		b->cursor_width = cap;
	else
		b->cursor_width = 64;

	ret = drmGetCap(b->drm.fd, DRM_CAP_CURSOR_HEIGHT, &cap);
	if (ret == 0)
		b->cursor_height = cap;
	else
		b->cursor_height = 64;

	ret = drmSetClientCap(b->drm.fd, DRM_CLIENT_CAP_UNIVERSAL_PLANES, 1);
	b->universal_planes = (ret == 0);
	weston_log("DRM: %s universal planes\n",
		   b->universal_planes ? "supports" : "does not support");

	return 0;
}

static struct gbm_device *
create_gbm_device(int fd)
{
	struct gbm_device *gbm;

	gl_renderer = weston_load_module("gl-renderer.so",
					 "gl_renderer_interface");
	if (!gl_renderer)
		return NULL;

	/* GBM will load a dri driver, but even though they need symbols from
	 * libglapi, in some version of Mesa they are not linked to it. Since
	 * only the gl-renderer module links to it, the call above won't make
	 * these symbols globally available, and loading the DRI driver fails.
	 * Workaround this by dlopen()'ing libglapi with RTLD_GLOBAL. */
	dlopen("libglapi.so.0", RTLD_LAZY | RTLD_GLOBAL);

	gbm = gbm_create_device(fd);

	return gbm;
}

/* When initializing EGL, if the preferred buffer format isn't available
 * we may be able to substitute an ARGB format for an XRGB one.
 *
 * This returns 0 if substitution isn't possible, but 0 might be a
 * legitimate format for other EGL platforms, so the caller is
 * responsible for checking for 0 before calling gl_renderer->create().
 *
 * This works around https://bugs.freedesktop.org/show_bug.cgi?id=89689
 * but it's entirely possible we'll see this again on other implementations.
 */
static int
fallback_format_for(uint32_t format)
{
	switch (format) {
	case GBM_FORMAT_XRGB8888:
		return GBM_FORMAT_ARGB8888;
	case GBM_FORMAT_XRGB2101010:
		return GBM_FORMAT_ARGB2101010;
	default:
		return 0;
	}
}

static int
drm_backend_create_gl_renderer(struct drm_backend *b)
{
	EGLint format[3] = {
		b->gbm_format,
		fallback_format_for(b->gbm_format),
		0,
	};
	int n_formats = 2;

	if (format[1])
		n_formats = 3;
	if (gl_renderer->display_create(b->compositor,
					EGL_PLATFORM_GBM_KHR,
					(void *)b->gbm,
					NULL,
					gl_renderer->opaque_attribs,
					format,
					n_formats) < 0) {
		return -1;
	}

	return 0;
}

static int
init_egl(struct drm_backend *b)
{
	b->gbm = create_gbm_device(b->drm.fd);

	if (!b->gbm)
		return -1;

	if (drm_backend_create_gl_renderer(b) < 0) {
		gbm_device_destroy(b->gbm);
		return -1;
	}

	return 0;
}

static int
init_pixman(struct drm_backend *b)
{
	return pixman_renderer_init(b->compositor);
}

/**
 * Create a drm_plane for a hardware plane
 *
 * Creates one drm_plane structure for a hardware plane, and initialises its
 * properties and formats.
 *
 * This function does not add the plane to the list of usable planes in Weston
 * itself; the caller is responsible for this.
 *
 * Call drm_plane_destroy to clean up the plane.
 *
 * @param b DRM compositor backend
 * @param kplane DRM plane to create
 */
static struct drm_plane *
drm_plane_create(struct drm_backend *b, const drmModePlane *kplane)
{
	struct drm_plane *plane;
	drmModeObjectProperties *props;

	static struct drm_property_enum_info plane_type_enums[] = {
		[WDRM_PLANE_TYPE_PRIMARY] = {
			.name = "Primary",
		},
		[WDRM_PLANE_TYPE_OVERLAY] = {
			.name = "Overlay",
		},
		[WDRM_PLANE_TYPE_CURSOR] = {
			.name = "Cursor",
		},
	};
	static const struct drm_property_info plane_props[] = {
		[WDRM_PLANE_TYPE] = {
			.name = "type",
			.enum_values = plane_type_enums,
			.num_enum_values = WDRM_PLANE_TYPE__COUNT,
		},
	};

	plane = zalloc(sizeof(*plane) + ((sizeof(uint32_t)) *
					  kplane->count_formats));
	if (!plane) {
		weston_log("%s: out of memory\n", __func__);
		return NULL;
	}

	plane->backend = b;
	plane->possible_crtcs = kplane->possible_crtcs;
	plane->plane_id = kplane->plane_id;
	plane->count_formats = kplane->count_formats;
	memcpy(plane->formats, kplane->formats,
	       kplane->count_formats * sizeof(kplane->formats[0]));

	props = drmModeObjectGetProperties(b->drm.fd, kplane->plane_id,
					   DRM_MODE_OBJECT_PLANE);
	if (!props) {
		weston_log("couldn't get plane properties\n");
		free(plane);
		return NULL;
	}
	drm_property_info_populate(b, plane_props, plane->props,
				   WDRM_PLANE__COUNT, props);
	plane->type =
		drm_property_get_value(&plane->props[WDRM_PLANE_TYPE],
				       props,
				       WDRM_PLANE_TYPE_OVERLAY);
	drmModeFreeObjectProperties(props);

	weston_plane_init(&plane->base, b->compositor, 0, 0);
	wl_list_insert(&b->plane_list, &plane->link);

	return plane;
}

/**
 * Destroy one DRM plane
 *
 * Destroy a DRM plane, removing it from screen and releasing its retained
 * buffers in the process. The counterpart to drm_plane_create.
 *
 * @param plane Plane to deallocate (will be freed)
 */
static void
drm_plane_destroy(struct drm_plane *plane)
{
	drmModeSetPlane(plane->backend->drm.fd, plane->plane_id, 0, 0, 0,
			0, 0, 0, 0, 0, 0, 0, 0);
	assert(!plane->fb_last);
	assert(!plane->fb_pending);
	drm_property_info_free(plane->props, WDRM_PLANE__COUNT);
	drm_fb_unref(plane->fb_current);
	weston_plane_release(&plane->base);
	wl_list_remove(&plane->link);
	free(plane);
}

/**
 * Initialise sprites (overlay planes)
 *
 * Walk the list of provided DRM planes, and add overlay planes.
 *
 * Call destroy_sprites to free these planes.
 *
 * @param b DRM compositor backend
 */
static void
create_sprites(struct drm_backend *b)
{
	drmModePlaneRes *kplane_res;
	drmModePlane *kplane;
	struct drm_plane *drm_plane;
	uint32_t i;

	kplane_res = drmModeGetPlaneResources(b->drm.fd);
	if (!kplane_res) {
		weston_log("failed to get plane resources: %s\n",
			strerror(errno));
		return;
	}

	for (i = 0; i < kplane_res->count_planes; i++) {
		kplane = drmModeGetPlane(b->drm.fd, kplane_res->planes[i]);
		if (!kplane)
			continue;

		drm_plane = drm_plane_create(b, kplane);
		drmModeFreePlane(kplane);
		if (!drm_plane)
			continue;

		if (drm_plane->type == WDRM_PLANE_TYPE_OVERLAY)
			weston_compositor_stack_plane(b->compositor,
						      &drm_plane->base,
						      &b->compositor->primary_plane);
	}

	drmModeFreePlaneResources(kplane_res);
}

/**
 * Clean up sprites (overlay planes)
 *
 * The counterpart to create_sprites.
 *
 * @param b DRM compositor backend
 */
static void
destroy_sprites(struct drm_backend *b)
{
	struct drm_plane *plane, *next;

	wl_list_for_each_safe(plane, next, &b->plane_list, link)
		drm_plane_destroy(plane);
}

/**
 * Add a mode to output's mode list
 *
 * Copy the supplied DRM mode into a Weston mode structure, and add it to the
 * output's mode list.
 *
 * @param output DRM output to add mode to
 * @param info DRM mode structure to add
 * @returns Newly-allocated Weston/DRM mode structure
 */
static struct drm_mode *
drm_output_add_mode(struct drm_output *output, const drmModeModeInfo *info)
{
	struct drm_mode *mode;
	uint64_t refresh;

	mode = malloc(sizeof *mode);
	if (mode == NULL)
		return NULL;

	mode->base.flags = 0;
	mode->base.width = info->hdisplay;
	mode->base.height = info->vdisplay;

	/* Calculate higher precision (mHz) refresh rate */
	refresh = (info->clock * 1000000LL / info->htotal +
		   info->vtotal / 2) / info->vtotal;

	if (info->flags & DRM_MODE_FLAG_INTERLACE)
		refresh *= 2;
	if (info->flags & DRM_MODE_FLAG_DBLSCAN)
		refresh /= 2;
	if (info->vscan > 1)
	    refresh /= info->vscan;

	mode->base.refresh = refresh;
	mode->mode_info = *info;

	if (info->type & DRM_MODE_TYPE_PREFERRED)
		mode->base.flags |= WL_OUTPUT_MODE_PREFERRED;

	wl_list_insert(output->base.mode_list.prev, &mode->base.link);

	return mode;
}

static int
drm_subpixel_to_wayland(int drm_value)
{
	switch (drm_value) {
	default:
	case DRM_MODE_SUBPIXEL_UNKNOWN:
		return WL_OUTPUT_SUBPIXEL_UNKNOWN;
	case DRM_MODE_SUBPIXEL_NONE:
		return WL_OUTPUT_SUBPIXEL_NONE;
	case DRM_MODE_SUBPIXEL_HORIZONTAL_RGB:
		return WL_OUTPUT_SUBPIXEL_HORIZONTAL_RGB;
	case DRM_MODE_SUBPIXEL_HORIZONTAL_BGR:
		return WL_OUTPUT_SUBPIXEL_HORIZONTAL_BGR;
	case DRM_MODE_SUBPIXEL_VERTICAL_RGB:
		return WL_OUTPUT_SUBPIXEL_VERTICAL_RGB;
	case DRM_MODE_SUBPIXEL_VERTICAL_BGR:
		return WL_OUTPUT_SUBPIXEL_VERTICAL_BGR;
	}
}

/* returns a value between 0-255 range, where higher is brighter */
static uint32_t
drm_get_backlight(struct drm_output *output)
{
	long brightness, max_brightness, norm;

	brightness = backlight_get_brightness(output->backlight);
	max_brightness = backlight_get_max_brightness(output->backlight);

	/* convert it on a scale of 0 to 255 */
	norm = (brightness * 255)/(max_brightness);

	return (uint32_t) norm;
}

/* values accepted are between 0-255 range */
static void
drm_set_backlight(struct weston_output *output_base, uint32_t value)
{
	struct drm_output *output = to_drm_output(output_base);
	long max_brightness, new_brightness;

	if (!output->backlight)
		return;

	if (value > 255)
		return;

	max_brightness = backlight_get_max_brightness(output->backlight);

	/* get denormalized value */
	new_brightness = (value * max_brightness) / 255;

	backlight_set_brightness(output->backlight, new_brightness);
}

static void
drm_set_dpms(struct weston_output *output_base, enum dpms_enum level)
{
	struct drm_output *output = to_drm_output(output_base);
	struct weston_compositor *ec = output_base->compositor;
	struct drm_backend *b = to_drm_backend(ec);
	struct drm_property_info *prop =
		&output->props_conn[WDRM_CONNECTOR_DPMS];
	int ret;

	if (!prop->prop_id)
		return;

	ret = drmModeConnectorSetProperty(b->drm.fd, output->connector_id,
					  prop->prop_id, level);
	if (ret) {
		weston_log("DRM: DPMS: failed property set for %s\n",
			   output->base.name);
		return;
	}

	output->dpms = level;
}

static const char * const connector_type_names[] = {
	[DRM_MODE_CONNECTOR_Unknown]     = "Unknown",
	[DRM_MODE_CONNECTOR_VGA]         = "VGA",
	[DRM_MODE_CONNECTOR_DVII]        = "DVI-I",
	[DRM_MODE_CONNECTOR_DVID]        = "DVI-D",
	[DRM_MODE_CONNECTOR_DVIA]        = "DVI-A",
	[DRM_MODE_CONNECTOR_Composite]   = "Composite",
	[DRM_MODE_CONNECTOR_SVIDEO]      = "SVIDEO",
	[DRM_MODE_CONNECTOR_LVDS]        = "LVDS",
	[DRM_MODE_CONNECTOR_Component]   = "Component",
	[DRM_MODE_CONNECTOR_9PinDIN]     = "DIN",
	[DRM_MODE_CONNECTOR_DisplayPort] = "DP",
	[DRM_MODE_CONNECTOR_HDMIA]       = "HDMI-A",
	[DRM_MODE_CONNECTOR_HDMIB]       = "HDMI-B",
	[DRM_MODE_CONNECTOR_TV]          = "TV",
	[DRM_MODE_CONNECTOR_eDP]         = "eDP",
#ifdef DRM_MODE_CONNECTOR_DSI
	[DRM_MODE_CONNECTOR_VIRTUAL]     = "Virtual",
	[DRM_MODE_CONNECTOR_DSI]         = "DSI",
#endif
};

/** Create a name given a DRM connector
 *
 * \param con The DRM connector whose type and id form the name.
 * \return A newly allocate string, or NULL on error. Must be free()'d
 * after use.
 *
 * The name does not identify the DRM display device.
 */
static char *
make_connector_name(const drmModeConnector *con)
{
	char *name;
	const char *type_name = NULL;
	int ret;

	if (con->connector_type < ARRAY_LENGTH(connector_type_names))
		type_name = connector_type_names[con->connector_type];

	if (!type_name)
		type_name = "UNNAMED";

	ret = asprintf(&name, "%s-%d", type_name, con->connector_type_id);
	if (ret < 0)
		return NULL;

	return name;
}

static int
find_crtc_for_connector(struct drm_backend *b,
			drmModeRes *resources, drmModeConnector *connector)
{
	drmModeEncoder *encoder;
	int i, j;
	int ret = -1;

	for (j = 0; j < connector->count_encoders; j++) {
		uint32_t possible_crtcs, encoder_id, crtc_id;

		encoder = drmModeGetEncoder(b->drm.fd, connector->encoders[j]);
		if (encoder == NULL) {
			weston_log("Failed to get encoder.\n");
			continue;
		}
		encoder_id = encoder->encoder_id;
		possible_crtcs = encoder->possible_crtcs;
		crtc_id = encoder->crtc_id;
		drmModeFreeEncoder(encoder);

		for (i = 0; i < resources->count_crtcs; i++) {
			if (!(possible_crtcs & (1 << i)))
				continue;

			if (drm_output_find_by_crtc(b, resources->crtcs[i]))
				continue;

			/* Try to preserve the existing
			 * CRTC -> encoder -> connector routing; it makes
			 * initialisation faster, and also since we have a
			 * very dumb picking algorithm, may preserve a better
			 * choice. */
			if (!connector->encoder_id ||
			    (encoder_id == connector->encoder_id &&
			     crtc_id == resources->crtcs[i]))
				return i;

			ret = i;
		}
	}

	return ret;
}

static void drm_output_fini_cursor_egl(struct drm_output *output)
{
	unsigned int i;

	for (i = 0; i < ARRAY_LENGTH(output->gbm_cursor_fb); i++) {
		drm_fb_unref(output->gbm_cursor_fb[i]);
		output->gbm_cursor_fb[i] = NULL;
	}
}

static int
drm_output_init_cursor_egl(struct drm_output *output, struct drm_backend *b)
{
	unsigned int i;

	for (i = 0; i < ARRAY_LENGTH(output->gbm_cursor_fb); i++) {
		struct gbm_bo *bo;

		bo = gbm_bo_create(b->gbm, b->cursor_width, b->cursor_height,
				   GBM_FORMAT_ARGB8888,
				   GBM_BO_USE_CURSOR | GBM_BO_USE_WRITE);
		if (!bo)
			goto err;

		output->gbm_cursor_fb[i] =
			drm_fb_get_from_bo(bo, b, GBM_FORMAT_ARGB8888,
					   BUFFER_CURSOR);
		if (!output->gbm_cursor_fb[i]) {
			gbm_bo_destroy(bo);
			goto err;
		}
	}

	return 0;

err:
	weston_log("cursor buffers unavailable, using gl cursors\n");
	b->cursors_are_broken = 1;
	drm_output_fini_cursor_egl(output);
	return -1;
}

/* Init output state that depends on gl or gbm */
static int
drm_output_init_egl(struct drm_output *output, struct drm_backend *b)
{
	EGLint format[2] = {
		output->gbm_format,
		fallback_format_for(output->gbm_format),
	};
	int n_formats = 1;

	output->gbm_surface = gbm_surface_create(b->gbm,
					     output->base.current_mode->width,
					     output->base.current_mode->height,
					     format[0],
					     GBM_BO_USE_SCANOUT |
					     GBM_BO_USE_RENDERING);
	if (!output->gbm_surface) {
		weston_log("failed to create gbm surface\n");
		return -1;
	}

	if (format[1])
		n_formats = 2;
	if (gl_renderer->output_window_create(&output->base,
					      (EGLNativeWindowType)output->gbm_surface,
					      output->gbm_surface,
					      gl_renderer->opaque_attribs,
					      format,
					      n_formats) < 0) {
		weston_log("failed to create gl renderer output state\n");
		gbm_surface_destroy(output->gbm_surface);
		return -1;
	}

	drm_output_init_cursor_egl(output, b);

	return 0;
}

static void
drm_output_fini_egl(struct drm_output *output)
{
	gl_renderer->output_destroy(&output->base);
	gbm_surface_destroy(output->gbm_surface);
	drm_output_fini_cursor_egl(output);
}

static int
drm_output_init_pixman(struct drm_output *output, struct drm_backend *b)
{
	int w = output->base.current_mode->width;
	int h = output->base.current_mode->height;
	uint32_t format = output->gbm_format;
	uint32_t pixman_format;
	unsigned int i;

	switch (format) {
		case GBM_FORMAT_XRGB8888:
			pixman_format = PIXMAN_x8r8g8b8;
			break;
		case GBM_FORMAT_RGB565:
			pixman_format = PIXMAN_r5g6b5;
			break;
		default:
			weston_log("Unsupported pixman format 0x%x\n", format);
			return -1;
	}

	/* FIXME error checking */
	for (i = 0; i < ARRAY_LENGTH(output->dumb); i++) {
		output->dumb[i] = drm_fb_create_dumb(b, w, h, format);
		if (!output->dumb[i])
			goto err;

		output->image[i] =
			pixman_image_create_bits(pixman_format, w, h,
						 output->dumb[i]->map,
						 output->dumb[i]->stride);
		if (!output->image[i])
			goto err;
	}

	if (pixman_renderer_output_create(&output->base) < 0)
		goto err;

	pixman_region32_init_rect(&output->previous_damage,
				  output->base.x, output->base.y, output->base.width, output->base.height);

	return 0;

err:
	for (i = 0; i < ARRAY_LENGTH(output->dumb); i++) {
		if (output->dumb[i])
			drm_fb_unref(output->dumb[i]);
		if (output->image[i])
			pixman_image_unref(output->image[i]);

		output->dumb[i] = NULL;
		output->image[i] = NULL;
	}

	return -1;
}

static void
drm_output_fini_pixman(struct drm_output *output)
{
	unsigned int i;

	pixman_renderer_output_destroy(&output->base);
	pixman_region32_fini(&output->previous_damage);

	for (i = 0; i < ARRAY_LENGTH(output->dumb); i++) {
		pixman_image_unref(output->image[i]);
		drm_fb_unref(output->dumb[i]);
		output->dumb[i] = NULL;
		output->image[i] = NULL;
	}
}

static void
edid_parse_string(const uint8_t *data, char text[])
{
	int i;
	int replaced = 0;

	/* this is always 12 bytes, but we can't guarantee it's null
	 * terminated or not junk. */
	strncpy(text, (const char *) data, 12);

	/* guarantee our new string is null-terminated */
	text[12] = '\0';

	/* remove insane chars */
	for (i = 0; text[i] != '\0'; i++) {
		if (text[i] == '\n' ||
		    text[i] == '\r') {
			text[i] = '\0';
			break;
		}
	}

	/* ensure string is printable */
	for (i = 0; text[i] != '\0'; i++) {
		if (!isprint(text[i])) {
			text[i] = '-';
			replaced++;
		}
	}

	/* if the string is random junk, ignore the string */
	if (replaced > 4)
		text[0] = '\0';
}

#define EDID_DESCRIPTOR_ALPHANUMERIC_DATA_STRING	0xfe
#define EDID_DESCRIPTOR_DISPLAY_PRODUCT_NAME		0xfc
#define EDID_DESCRIPTOR_DISPLAY_PRODUCT_SERIAL_NUMBER	0xff
#define EDID_OFFSET_DATA_BLOCKS				0x36
#define EDID_OFFSET_LAST_BLOCK				0x6c
#define EDID_OFFSET_PNPID				0x08
#define EDID_OFFSET_SERIAL				0x0c

static int
edid_parse(struct drm_edid *edid, const uint8_t *data, size_t length)
{
	int i;
	uint32_t serial_number;

	/* check header */
	if (length < 128)
		return -1;
	if (data[0] != 0x00 || data[1] != 0xff)
		return -1;

	/* decode the PNP ID from three 5 bit words packed into 2 bytes
	 * /--08--\/--09--\
	 * 7654321076543210
	 * |\---/\---/\---/
	 * R  C1   C2   C3 */
	edid->pnp_id[0] = 'A' + ((data[EDID_OFFSET_PNPID + 0] & 0x7c) / 4) - 1;
	edid->pnp_id[1] = 'A' + ((data[EDID_OFFSET_PNPID + 0] & 0x3) * 8) + ((data[EDID_OFFSET_PNPID + 1] & 0xe0) / 32) - 1;
	edid->pnp_id[2] = 'A' + (data[EDID_OFFSET_PNPID + 1] & 0x1f) - 1;
	edid->pnp_id[3] = '\0';

	/* maybe there isn't a ASCII serial number descriptor, so use this instead */
	serial_number = (uint32_t) data[EDID_OFFSET_SERIAL + 0];
	serial_number += (uint32_t) data[EDID_OFFSET_SERIAL + 1] * 0x100;
	serial_number += (uint32_t) data[EDID_OFFSET_SERIAL + 2] * 0x10000;
	serial_number += (uint32_t) data[EDID_OFFSET_SERIAL + 3] * 0x1000000;
	if (serial_number > 0)
		sprintf(edid->serial_number, "%lu", (unsigned long) serial_number);

	/* parse EDID data */
	for (i = EDID_OFFSET_DATA_BLOCKS;
	     i <= EDID_OFFSET_LAST_BLOCK;
	     i += 18) {
		/* ignore pixel clock data */
		if (data[i] != 0)
			continue;
		if (data[i+2] != 0)
			continue;

		/* any useful blocks? */
		if (data[i+3] == EDID_DESCRIPTOR_DISPLAY_PRODUCT_NAME) {
			edid_parse_string(&data[i+5],
					  edid->monitor_name);
		} else if (data[i+3] == EDID_DESCRIPTOR_DISPLAY_PRODUCT_SERIAL_NUMBER) {
			edid_parse_string(&data[i+5],
					  edid->serial_number);
		} else if (data[i+3] == EDID_DESCRIPTOR_ALPHANUMERIC_DATA_STRING) {
			edid_parse_string(&data[i+5],
					  edid->eisa_id);
		}
	}
	return 0;
}

static void
find_and_parse_output_edid(struct drm_backend *b, struct drm_output *output,
			   drmModeObjectPropertiesPtr props)
{
	drmModePropertyBlobPtr edid_blob = NULL;
	uint32_t blob_id;
	int rc;

	blob_id =
		drm_property_get_value(&output->props_conn[WDRM_CONNECTOR_EDID],
				       props, 0);
	if (!blob_id)
		return;

	edid_blob = drmModeGetPropertyBlob(b->drm.fd, blob_id);
	if (!edid_blob)
		return;

	rc = edid_parse(&output->edid,
			edid_blob->data,
			edid_blob->length);
	if (!rc) {
		weston_log("EDID data '%s', '%s', '%s'\n",
			   output->edid.pnp_id,
			   output->edid.monitor_name,
			   output->edid.serial_number);
		if (output->edid.pnp_id[0] != '\0')
			output->base.make = output->edid.pnp_id;
		if (output->edid.monitor_name[0] != '\0')
			output->base.model = output->edid.monitor_name;
		if (output->edid.serial_number[0] != '\0')
			output->base.serial_number = output->edid.serial_number;
	}
	drmModeFreePropertyBlob(edid_blob);
}


static int
parse_modeline(const char *s, drmModeModeInfo *mode)
{
	char hsync[16];
	char vsync[16];
	float fclock;

	mode->type = DRM_MODE_TYPE_USERDEF;
	mode->hskew = 0;
	mode->vscan = 0;
	mode->vrefresh = 0;
	mode->flags = 0;

	if (sscanf(s, "%f %hd %hd %hd %hd %hd %hd %hd %hd %15s %15s",
		   &fclock,
		   &mode->hdisplay,
		   &mode->hsync_start,
		   &mode->hsync_end,
		   &mode->htotal,
		   &mode->vdisplay,
		   &mode->vsync_start,
		   &mode->vsync_end,
		   &mode->vtotal, hsync, vsync) != 11)
		return -1;

	mode->clock = fclock * 1000;
	if (strcmp(hsync, "+hsync") == 0)
		mode->flags |= DRM_MODE_FLAG_PHSYNC;
	else if (strcmp(hsync, "-hsync") == 0)
		mode->flags |= DRM_MODE_FLAG_NHSYNC;
	else
		return -1;

	if (strcmp(vsync, "+vsync") == 0)
		mode->flags |= DRM_MODE_FLAG_PVSYNC;
	else if (strcmp(vsync, "-vsync") == 0)
		mode->flags |= DRM_MODE_FLAG_NVSYNC;
	else
		return -1;

	snprintf(mode->name, sizeof mode->name, "%dx%d@%.3f",
		 mode->hdisplay, mode->vdisplay, fclock);

	return 0;
}

static void
setup_output_seat_constraint(struct drm_backend *b,
			     struct weston_output *output,
			     const char *s)
{
	if (strcmp(s, "") != 0) {
		struct weston_pointer *pointer;
		struct udev_seat *seat;

		seat = udev_seat_get_named(&b->input, s);
		if (!seat)
			return;

		seat->base.output = output;

		pointer = weston_seat_get_pointer(&seat->base);
		if (pointer)
			weston_pointer_clamp(pointer,
					     &pointer->x,
					     &pointer->y);
	}
}

static int
parse_gbm_format(const char *s, uint32_t default_value, uint32_t *gbm_format)
{
	int ret = 0;

	if (s == NULL)
		*gbm_format = default_value;
	else if (strcmp(s, "xrgb8888") == 0)
		*gbm_format = GBM_FORMAT_XRGB8888;
	else if (strcmp(s, "rgb565") == 0)
		*gbm_format = GBM_FORMAT_RGB565;
	else if (strcmp(s, "xrgb2101010") == 0)
		*gbm_format = GBM_FORMAT_XRGB2101010;
	else {
		weston_log("fatal: unrecognized pixel format: %s\n", s);
		ret = -1;
	}

	return ret;
}

/**
 * Choose suitable mode for an output
 *
 * Find the most suitable mode to use for initial setup (or reconfiguration on
 * hotplug etc) for a DRM output.
 *
 * @param output DRM output to choose mode for
 * @param kind Strategy and preference to use when choosing mode
 * @param width Desired width for this output
 * @param height Desired height for this output
 * @param current_mode Mode currently being displayed on this output
 * @param modeline Manually-entered mode (may be NULL)
 * @returns A mode from the output's mode list, or NULL if none available
 */
static struct drm_mode *
drm_output_choose_initial_mode(struct drm_backend *backend,
			       struct drm_output *output,
			       enum weston_drm_backend_output_mode mode,
			       const char *modeline,
			       const drmModeModeInfo *current_mode)
{
	struct drm_mode *preferred = NULL;
	struct drm_mode *current = NULL;
	struct drm_mode *configured = NULL;
	struct drm_mode *best = NULL;
	struct drm_mode *drm_mode;
	drmModeModeInfo drm_modeline;
	int32_t width = 0;
	int32_t height = 0;
	uint32_t refresh = 0;
	int n;

	if (mode == WESTON_DRM_BACKEND_OUTPUT_PREFERRED && modeline) {
		n = sscanf(modeline, "%dx%d@%d", &width, &height, &refresh);
		if (n != 2 && n != 3) {
			width = -1;

			if (parse_modeline(modeline, &drm_modeline) == 0) {
				configured = drm_output_add_mode(output, &drm_modeline);
				if (!configured)
					return NULL;
			} else {
				weston_log("Invalid modeline \"%s\" for output %s\n",
					   modeline, output->base.name);
			}
		}
	}

	wl_list_for_each_reverse(drm_mode, &output->base.mode_list, base.link) {
		if (width == drm_mode->base.width &&
		    height == drm_mode->base.height &&
		    (refresh == 0 || refresh == drm_mode->mode_info.vrefresh))
			configured = drm_mode;

		if (memcmp(current_mode, &drm_mode->mode_info,
			   sizeof *current_mode) == 0)
			current = drm_mode;

		if (drm_mode->base.flags & WL_OUTPUT_MODE_PREFERRED)
			preferred = drm_mode;

		best = drm_mode;
	}

	if (current == NULL && current_mode->clock != 0) {
		current = drm_output_add_mode(output, current_mode);
		if (!current)
			return NULL;
	}

	if (mode == WESTON_DRM_BACKEND_OUTPUT_CURRENT)
		configured = current;

	if (configured)
		return configured;

	if (preferred)
		return preferred;

	if (current)
		return current;

	if (best)
		return best;

	weston_log("no available modes for %s\n", output->base.name);
	return NULL;
}

static int
connector_get_current_mode(drmModeConnector *connector, int drm_fd,
			   drmModeModeInfo *mode)
{
	drmModeEncoder *encoder;
	drmModeCrtc *crtc;

	/* Get the current mode on the crtc that's currently driving
	 * this connector. */
	encoder = drmModeGetEncoder(drm_fd, connector->encoder_id);
	memset(mode, 0, sizeof *mode);
	if (encoder != NULL) {
		crtc = drmModeGetCrtc(drm_fd, encoder->crtc_id);
		drmModeFreeEncoder(encoder);
		if (crtc == NULL)
			return -1;
		if (crtc->mode_valid)
			*mode = crtc->mode;
		drmModeFreeCrtc(crtc);
	}

	return 0;
}

static int
drm_output_set_mode(struct weston_output *base,
		    enum weston_drm_backend_output_mode mode,
		    const char *modeline)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);

	struct drm_mode *current;
	drmModeModeInfo crtc_mode;

	output->base.make = "unknown";
	output->base.model = "unknown";
	output->base.serial_number = "unknown";

	if (connector_get_current_mode(output->connector, b->drm.fd, &crtc_mode) < 0)
		return -1;

	current = drm_output_choose_initial_mode(b, output, mode, modeline, &crtc_mode);
	if (!current)
		return -1;

	output->base.current_mode = &current->base;
	output->base.current_mode->flags |= WL_OUTPUT_MODE_CURRENT;

	/* Set native_ fields, so weston_output_mode_switch_to_native() works */
	output->base.native_mode = output->base.current_mode;
	output->base.native_scale = output->base.current_scale;

	output->base.mm_width = output->connector->mmWidth;
	output->base.mm_height = output->connector->mmHeight;

	return 0;
}

static void
drm_output_set_gbm_format(struct weston_output *base,
			  const char *gbm_format)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);

	if (parse_gbm_format(gbm_format, b->gbm_format, &output->gbm_format) == -1)
		output->gbm_format = b->gbm_format;
}

static void
drm_output_set_seat(struct weston_output *base,
		    const char *seat)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);

	setup_output_seat_constraint(b, &output->base,
				     seat ? seat : "");
}

static int
drm_output_enable(struct weston_output *base)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);
	struct weston_mode *m;

	if (b->pageflip_timeout)
		drm_output_pageflip_timer_create(output);

	if (b->use_pixman) {
		if (drm_output_init_pixman(output, b) < 0) {
			weston_log("Failed to init output pixman state\n");
			goto err;
		}
	} else if (drm_output_init_egl(output, b) < 0) {
		weston_log("Failed to init output gl state\n");
		goto err;
	}

	if (output->backlight) {
		weston_log("Initialized backlight, device %s\n",
			   output->backlight->path);
		output->base.set_backlight = drm_set_backlight;
		output->base.backlight_current = drm_get_backlight(output);
	} else {
		weston_log("Failed to initialize backlight\n");
	}

	output->base.start_repaint_loop = drm_output_start_repaint_loop;
	output->base.repaint = drm_output_repaint;
	output->base.assign_planes = drm_assign_planes;
	output->base.set_dpms = drm_set_dpms;
	output->base.switch_mode = drm_output_switch_mode;

	output->base.gamma_size = output->original_crtc->gamma_size;
	output->base.set_gamma = drm_output_set_gamma;

	output->base.subpixel = drm_subpixel_to_wayland(output->connector->subpixel);

	if (output->connector->connector_type == DRM_MODE_CONNECTOR_LVDS ||
	    output->connector->connector_type == DRM_MODE_CONNECTOR_eDP)
		output->base.connection_internal = true;

	weston_plane_init(&output->cursor_plane, b->compositor,
			  INT32_MIN, INT32_MIN);
	weston_plane_init(&output->scanout_plane, b->compositor, 0, 0);

	weston_compositor_stack_plane(b->compositor, &output->cursor_plane, NULL);
	weston_compositor_stack_plane(b->compositor, &output->scanout_plane,
				      &b->compositor->primary_plane);

	weston_log("Output %s, (connector %d, crtc %d)\n",
		   output->base.name, output->connector_id, output->crtc_id);
	wl_list_for_each(m, &output->base.mode_list, link)
		weston_log_continue(STAMP_SPACE "mode %dx%d@%.1f%s%s%s\n",
				    m->width, m->height, m->refresh / 1000.0,
				    m->flags & WL_OUTPUT_MODE_PREFERRED ?
				    ", preferred" : "",
				    m->flags & WL_OUTPUT_MODE_CURRENT ?
				    ", current" : "",
				    output->connector->count_modes == 0 ?
				    ", built-in" : "");

	output->state_invalid = true;

	return 0;

err:
	return -1;
}

static void
drm_output_deinit(struct weston_output *base)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);

	/* output->fb_last and output->fb_pending must not be set here;
	 * destroy_pending/disable_pending exist to guarantee exactly this. */
	assert(!output->fb_last);
	assert(!output->fb_pending);
	drm_fb_unref(output->fb_current);
	output->fb_current = NULL;

	if (b->use_pixman)
		drm_output_fini_pixman(output);
	else
		drm_output_fini_egl(output);

	weston_plane_release(&output->scanout_plane);
	weston_plane_release(&output->cursor_plane);

	/* Turn off hardware cursor */
	drmModeSetCursor(b->drm.fd, output->crtc_id, 0, 0, 0);
}

static void
drm_output_destroy(struct weston_output *base)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);
	struct drm_mode *drm_mode, *next;
	drmModeCrtcPtr origcrtc = output->original_crtc;

	if (output->page_flip_pending) {
		output->destroy_pending = 1;
		weston_log("destroy output while page flip pending\n");
		return;
	}

	if (output->base.enabled)
		drm_output_deinit(&output->base);

	wl_list_for_each_safe(drm_mode, next, &output->base.mode_list,
			      base.link) {
		wl_list_remove(&drm_mode->base.link);
		free(drm_mode);
	}

	if (origcrtc) {
		/* Restore original CRTC state */
		drmModeSetCrtc(b->drm.fd, origcrtc->crtc_id, origcrtc->buffer_id,
			       origcrtc->x, origcrtc->y,
			       &output->connector_id, 1, &origcrtc->mode);
		drmModeFreeCrtc(origcrtc);
	}

	if (output->pageflip_timer)
		wl_event_source_remove(output->pageflip_timer);

	weston_output_destroy(&output->base);

	drm_property_info_free(output->props_conn, WDRM_CONNECTOR__COUNT);

	drmModeFreeConnector(output->connector);

	if (output->backlight)
		backlight_destroy(output->backlight);

	free(output);
}

static int
drm_output_disable(struct weston_output *base)
{
	struct drm_output *output = to_drm_output(base);
	struct drm_backend *b = to_drm_backend(base->compositor);

	if (output->page_flip_pending) {
		output->disable_pending = 1;
		return -1;
	}

	if (output->base.enabled)
		drm_output_deinit(&output->base);

	output->disable_pending = 0;

	weston_log("Disabling output %s\n", output->base.name);
	drmModeSetCrtc(b->drm.fd, output->crtc_id,
		       0, 0, 0, 0, 0, NULL);

	return 0;
}

/**
 * Create a Weston output structure
 *
 * Given a DRM connector, create a matching drm_output structure and add it
 * to Weston's output list. It also takes ownership of the connector, which
 * is released when output is destroyed.
 *
 * @param b Weston backend structure
 * @param resources DRM resources for this device
 * @param connector DRM connector to use for this new output
 * @param drm_device udev device pointer
 * @returns 0 on success, or -1 on failure
 */
static int
create_output_for_connector(struct drm_backend *b,
			    drmModeRes *resources,
			    drmModeConnector *connector,
			    struct udev_device *drm_device)
{
	struct drm_output *output;
	drmModeObjectPropertiesPtr props;
	struct drm_mode *drm_mode;
	int i;

	static const struct drm_property_info connector_props[] = {
		[WDRM_CONNECTOR_EDID] = { .name = "EDID" },
		[WDRM_CONNECTOR_DPMS] = { .name = "DPMS" },
	};

	i = find_crtc_for_connector(b, resources, connector);
	if (i < 0) {
		weston_log("No usable crtc/encoder pair for connector.\n");
		goto err;
	}

	output = zalloc(sizeof *output);
	if (output == NULL)
		goto err;

	output->connector = connector;
	output->crtc_id = resources->crtcs[i];
	output->pipe = i;
	output->connector_id = connector->connector_id;

	output->backlight = backlight_init(drm_device,
					   connector->connector_type);

	output->original_crtc = drmModeGetCrtc(b->drm.fd, output->crtc_id);

	output->base.enable = drm_output_enable;
	output->base.destroy = drm_output_destroy;
	output->base.disable = drm_output_disable;
	output->base.name = make_connector_name(connector);

	output->destroy_pending = 0;
	output->disable_pending = 0;

	props = drmModeObjectGetProperties(b->drm.fd, connector->connector_id,
					   DRM_MODE_OBJECT_CONNECTOR);
	if (!props) {
		weston_log("failed to get connector properties\n");
		goto err;
	}
	drm_property_info_populate(b, connector_props, output->props_conn,
				   WDRM_CONNECTOR__COUNT, props);
	find_and_parse_output_edid(b, output, props);
	drmModeFreeObjectProperties(props);

	weston_output_init(&output->base, b->compositor);

	wl_list_init(&output->base.mode_list);

	for (i = 0; i < output->connector->count_modes; i++) {
		drm_mode = drm_output_add_mode(output, &output->connector->modes[i]);
		if (!drm_mode) {
			drm_output_destroy(&output->base);
			return -1;
		}
	}

	weston_compositor_add_pending_output(&output->base, b->compositor);

	return 0;

err:
	drmModeFreeConnector(connector);

	return -1;
}

static int
create_outputs(struct drm_backend *b, struct udev_device *drm_device)
{
	drmModeConnector *connector;
	drmModeRes *resources;
	int i;

	resources = drmModeGetResources(b->drm.fd);
	if (!resources) {
		weston_log("drmModeGetResources failed\n");
		return -1;
	}

	b->min_width  = resources->min_width;
	b->max_width  = resources->max_width;
	b->min_height = resources->min_height;
	b->max_height = resources->max_height;

	for (i = 0; i < resources->count_connectors; i++) {
		int ret;

		connector = drmModeGetConnector(b->drm.fd,
						resources->connectors[i]);
		if (connector == NULL)
			continue;

		if (connector->connection == DRM_MODE_CONNECTED) {
			ret = create_output_for_connector(b, resources,
							  connector, drm_device);
			if (ret < 0)
				weston_log("failed to create new connector\n");
		} else {
			drmModeFreeConnector(connector);
		}
	}

	if (wl_list_empty(&b->compositor->output_list) &&
	    wl_list_empty(&b->compositor->pending_output_list))
		weston_log("No currently active connector found.\n");

	drmModeFreeResources(resources);

	return 0;
}

static void
update_outputs(struct drm_backend *b, struct udev_device *drm_device)
{
	drmModeConnector *connector;
	drmModeRes *resources;
	struct drm_output *output, *next;
	uint32_t *connected;
	int i;

	resources = drmModeGetResources(b->drm.fd);
	if (!resources) {
		weston_log("drmModeGetResources failed\n");
		return;
	}

	connected = calloc(resources->count_connectors, sizeof(uint32_t));
	if (!connected) {
		drmModeFreeResources(resources);
		return;
	}

	/* collect new connects */
	for (i = 0; i < resources->count_connectors; i++) {
		uint32_t connector_id = resources->connectors[i];

		connector = drmModeGetConnector(b->drm.fd, connector_id);
		if (connector == NULL)
			continue;

		if (connector->connection != DRM_MODE_CONNECTED) {
			drmModeFreeConnector(connector);
			continue;
		}

		connected[i] = connector_id;

		if (drm_output_find_by_connector(b, connector_id)) {
			drmModeFreeConnector(connector);
			continue;
		}

		create_output_for_connector(b, resources,
					    connector, drm_device);
		weston_log("connector %d connected\n", connector_id);
	}

	wl_list_for_each_safe(output, next, &b->compositor->output_list,
			      base.link) {
		bool disconnected = true;

		for (i = 0; i < resources->count_connectors; i++) {
			if (connected[i] == output->connector_id) {
				disconnected = false;
				break;
			}
		}

		if (!disconnected)
			continue;

		weston_log("connector %d disconnected\n", output->connector_id);
		drm_output_destroy(&output->base);
	}

	wl_list_for_each_safe(output, next, &b->compositor->pending_output_list,
			      base.link) {
		bool disconnected = true;

		for (i = 0; i < resources->count_connectors; i++) {
			if (connected[i] == output->connector_id) {
				disconnected = false;
				break;
			}
		}

		if (!disconnected)
			continue;

		weston_log("connector %d disconnected\n", output->connector_id);
		drm_output_destroy(&output->base);
	}

	free(connected);
	drmModeFreeResources(resources);
}

static int
udev_event_is_hotplug(struct drm_backend *b, struct udev_device *device)
{
	const char *sysnum;
	const char *val;

	sysnum = udev_device_get_sysnum(device);
	if (!sysnum || atoi(sysnum) != b->drm.id)
		return 0;

	val = udev_device_get_property_value(device, "HOTPLUG");
	if (!val)
		return 0;

	return strcmp(val, "1") == 0;
}

static int
udev_drm_event(int fd, uint32_t mask, void *data)
{
	struct drm_backend *b = data;
	struct udev_device *event;

	event = udev_monitor_receive_device(b->udev_monitor);

	if (udev_event_is_hotplug(b, event))
		update_outputs(b, event);

	udev_device_unref(event);

	return 1;
}

static void
drm_restore(struct weston_compositor *ec)
{
	weston_launcher_restore(ec->launcher);
}

static void
drm_destroy(struct weston_compositor *ec)
{
	struct drm_backend *b = to_drm_backend(ec);

	udev_input_destroy(&b->input);

	wl_event_source_remove(b->udev_drm_source);
	wl_event_source_remove(b->drm_source);

	destroy_sprites(b);

	weston_compositor_shutdown(ec);

	if (b->gbm)
		gbm_device_destroy(b->gbm);

	weston_launcher_destroy(ec->launcher);

	close(b->drm.fd);
	free(b);
}

static void
session_notify(struct wl_listener *listener, void *data)
{
	struct weston_compositor *compositor = data;
	struct drm_backend *b = to_drm_backend(compositor);
	struct drm_plane *plane;
	struct drm_output *output;

	if (compositor->session_active) {
		weston_log("activating session\n");
		weston_compositor_wake(compositor);
		weston_compositor_damage_all(compositor);

		wl_list_for_each(output, &compositor->output_list, base.link)
			output->state_invalid = true;

		udev_input_enable(&b->input);
	} else {
		weston_log("deactivating session\n");
		udev_input_disable(&b->input);

		weston_compositor_offscreen(compositor);

		/* If we have a repaint scheduled (either from a
		 * pending pageflip or the idle handler), make sure we
		 * cancel that so we don't try to pageflip when we're
		 * vt switched away.  The OFFSCREEN state will prevent
		 * further attempts at repainting.  When we switch
		 * back, we schedule a repaint, which will process
		 * pending frame callbacks. */

		wl_list_for_each(output, &compositor->output_list, base.link) {
			output->base.repaint_needed = false;
			drmModeSetCursor(b->drm.fd, output->crtc_id, 0, 0, 0);
		}

		output = container_of(compositor->output_list.next,
				      struct drm_output, base.link);

		wl_list_for_each(plane, &b->plane_list, link) {
			if (plane->type != WDRM_PLANE_TYPE_OVERLAY)
				continue;

			drmModeSetPlane(b->drm.fd,
					plane->plane_id,
					output->crtc_id, 0, 0,
					0, 0, 0, 0, 0, 0, 0, 0);
		}
	}
}

/**
 * Determines whether or not a device is capable of modesetting. If successful,
 * sets b->drm.fd and b->drm.filename to the opened device.
 */
static bool
drm_device_is_kms(struct drm_backend *b, struct udev_device *device)
{
	const char *filename = udev_device_get_devnode(device);
	const char *sysnum = udev_device_get_sysnum(device);
	drmModeRes *res;
	int id, fd;

	if (!filename)
		return false;

	fd = weston_launcher_open(b->compositor->launcher, filename, O_RDWR);
	if (fd < 0)
		return false;

	res = drmModeGetResources(fd);
	if (!res)
		goto out_fd;

	if (res->count_crtcs <= 0 || res->count_connectors <= 0 ||
	    res->count_encoders <= 0)
		goto out_res;

	if (sysnum)
		id = atoi(sysnum);
	if (!sysnum || id < 0) {
		weston_log("couldn't get sysnum for device %s\n", filename);
		goto out_res;
	}

	/* We can be called successfully on multiple devices; if we have,
	 * clean up old entries. */
	if (b->drm.fd >= 0)
		weston_launcher_close(b->compositor->launcher, b->drm.fd);
	free(b->drm.filename);

	b->drm.fd = fd;
	b->drm.id = id;
	b->drm.filename = strdup(filename);

	drmModeFreeResources(res);

	return true;

out_res:
	drmModeFreeResources(res);
out_fd:
	weston_launcher_close(b->compositor->launcher, fd);
	return false;
}

/*
 * Find primary GPU
 * Some systems may have multiple DRM devices attached to a single seat. This
 * function loops over all devices and tries to find a PCI device with the
 * boot_vga sysfs attribute set to 1.
 * If no such device is found, the first DRM device reported by udev is used.
 * Devices are also vetted to make sure they are are capable of modesetting,
 * rather than pure render nodes (GPU with no display), or pure
 * memory-allocation devices (VGEM).
 */
static struct udev_device*
find_primary_gpu(struct drm_backend *b, const char *seat)
{
	struct udev_enumerate *e;
	struct udev_list_entry *entry;
	const char *path, *device_seat, *id;
	struct udev_device *device, *drm_device, *pci;

	e = udev_enumerate_new(b->udev);
	udev_enumerate_add_match_subsystem(e, "drm");
	udev_enumerate_add_match_sysname(e, "card[0-9]*");

	udev_enumerate_scan_devices(e);
	drm_device = NULL;
	udev_list_entry_foreach(entry, udev_enumerate_get_list_entry(e)) {
		bool is_boot_vga = false;

		path = udev_list_entry_get_name(entry);
		device = udev_device_new_from_syspath(b->udev, path);
		if (!device)
			continue;
		device_seat = udev_device_get_property_value(device, "ID_SEAT");
		if (!device_seat)
			device_seat = default_seat;
		if (strcmp(device_seat, seat)) {
			udev_device_unref(device);
			continue;
		}

		pci = udev_device_get_parent_with_subsystem_devtype(device,
								"pci", NULL);
		if (pci) {
			id = udev_device_get_sysattr_value(pci, "boot_vga");
			if (id && !strcmp(id, "1"))
				is_boot_vga = true;
		}

		/* If we already have a modesetting-capable device, and this
		 * device isn't our boot-VGA device, we aren't going to use
		 * it. */
		if (!is_boot_vga && drm_device) {
			udev_device_unref(device);
			continue;
		}

		/* Make sure this device is actually capable of modesetting;
		 * if this call succeeds, b->drm.{fd,filename} will be set,
		 * and any old values freed. */
		if (!drm_device_is_kms(b, device)) {
			udev_device_unref(device);
			continue;
		}

		/* There can only be one boot_vga device, and we try to use it
		 * at all costs. */
		if (is_boot_vga) {
			if (drm_device)
				udev_device_unref(drm_device);
			drm_device = device;
			break;
		}

		/* Per the (!is_boot_vga && drm_device) test above, we only
		 * trump existing saved devices with boot-VGA devices, so if
		 * we end up here, this must be the first device we've seen. */
		assert(!drm_device);
		drm_device = device;
	}

	/* If we're returning a device to use, we must have an open FD for
	 * it. */
	assert(!!drm_device == (b->drm.fd >= 0));

	udev_enumerate_unref(e);
	return drm_device;
}

static void
planes_binding(struct weston_keyboard *keyboard, uint32_t time, uint32_t key,
	       void *data)
{
	struct drm_backend *b = data;

	switch (key) {
	case KEY_C:
		b->cursors_are_broken ^= 1;
		break;
	case KEY_V:
		b->sprites_are_broken ^= 1;
		break;
	case KEY_O:
		b->sprites_hidden ^= 1;
		break;
	default:
		break;
	}
}

#ifdef BUILD_VAAPI_RECORDER
static void
recorder_destroy(struct drm_output *output)
{
	vaapi_recorder_destroy(output->recorder);
	output->recorder = NULL;

	output->base.disable_planes--;

	wl_list_remove(&output->recorder_frame_listener.link);
	weston_log("[libva recorder] done\n");
}

static void
recorder_frame_notify(struct wl_listener *listener, void *data)
{
	struct drm_output *output;
	struct drm_backend *b;
	int fd, ret;

	output = container_of(listener, struct drm_output,
			      recorder_frame_listener);
	b = to_drm_backend(output->base.compositor);

	if (!output->recorder)
		return;

	ret = drmPrimeHandleToFD(b->drm.fd, output->fb_current->handle,
				 DRM_CLOEXEC, &fd);
	if (ret) {
		weston_log("[libva recorder] "
			   "failed to create prime fd for front buffer\n");
		return;
	}

	ret = vaapi_recorder_frame(output->recorder, fd,
				   output->fb_current->stride);
	if (ret < 0) {
		weston_log("[libva recorder] aborted: %m\n");
		recorder_destroy(output);
	}
}

static void *
create_recorder(struct drm_backend *b, int width, int height,
		const char *filename)
{
	int fd;
	drm_magic_t magic;

	fd = open(b->drm.filename, O_RDWR | O_CLOEXEC);
	if (fd < 0)
		return NULL;

	drmGetMagic(fd, &magic);
	drmAuthMagic(b->drm.fd, magic);

	return vaapi_recorder_create(fd, width, height, filename);
}

static void
recorder_binding(struct weston_keyboard *keyboard, uint32_t time, uint32_t key,
		 void *data)
{
	struct drm_backend *b = data;
	struct drm_output *output;
	int width, height;

	output = container_of(b->compositor->output_list.next,
			      struct drm_output, base.link);

	if (!output->recorder) {
		if (output->gbm_format != GBM_FORMAT_XRGB8888) {
			weston_log("failed to start vaapi recorder: "
				   "output format not supported\n");
			return;
		}

		width = output->base.current_mode->width;
		height = output->base.current_mode->height;

		output->recorder =
			create_recorder(b, width, height, "capture.h264");
		if (!output->recorder) {
			weston_log("failed to create vaapi recorder\n");
			return;
		}

		output->base.disable_planes++;

		output->recorder_frame_listener.notify = recorder_frame_notify;
		wl_signal_add(&output->base.frame_signal,
			      &output->recorder_frame_listener);

		weston_output_schedule_repaint(&output->base);

		weston_log("[libva recorder] initialized\n");
	} else {
		recorder_destroy(output);
	}
}
#else
static void
recorder_binding(struct weston_keyboard *keyboard, uint32_t time, uint32_t key,
		 void *data)
{
	weston_log("Compiled without libva support\n");
}
#endif

static void
switch_to_gl_renderer(struct drm_backend *b)
{
	struct drm_output *output;
	bool dmabuf_support_inited;

	if (!b->use_pixman)
		return;

	dmabuf_support_inited = !!b->compositor->renderer->import_dmabuf;

	weston_log("Switching to GL renderer\n");

	b->gbm = create_gbm_device(b->drm.fd);
	if (!b->gbm) {
		weston_log("Failed to create gbm device. "
			   "Aborting renderer switch\n");
		return;
	}

	wl_list_for_each(output, &b->compositor->output_list, base.link)
		pixman_renderer_output_destroy(&output->base);

	b->compositor->renderer->destroy(b->compositor);

	if (drm_backend_create_gl_renderer(b) < 0) {
		gbm_device_destroy(b->gbm);
		weston_log("Failed to create GL renderer. Quitting.\n");
		/* FIXME: we need a function to shutdown cleanly */
		assert(0);
	}

	wl_list_for_each(output, &b->compositor->output_list, base.link)
		drm_output_init_egl(output, b);

	b->use_pixman = 0;

	if (!dmabuf_support_inited && b->compositor->renderer->import_dmabuf) {
		if (linux_dmabuf_setup(b->compositor) < 0)
			weston_log("Error: initializing dmabuf "
				   "support failed.\n");
	}
}

static void
renderer_switch_binding(struct weston_keyboard *keyboard, uint32_t time,
			uint32_t key, void *data)
{
	struct drm_backend *b =
		to_drm_backend(keyboard->seat->compositor);

	switch_to_gl_renderer(b);
}

static const struct weston_drm_output_api api = {
	drm_output_set_mode,
	drm_output_set_gbm_format,
	drm_output_set_seat,
};

static struct drm_backend *
drm_backend_create(struct weston_compositor *compositor,
		   struct weston_drm_backend_config *config)
{
	struct drm_backend *b;
	struct udev_device *drm_device;
	struct wl_event_loop *loop;
	const char *seat_id = default_seat;
	int ret;

	weston_log("initializing drm backend\n");

	b = zalloc(sizeof *b);
	if (b == NULL)
		return NULL;

	b->drm.fd = -1;

	/*
	 * KMS support for hardware planes cannot properly synchronize
	 * without nuclear page flip. Without nuclear/atomic, hw plane
	 * and cursor plane updates would either tear or cause extra
	 * waits for vblanks which means dropping the compositor framerate
	 * to a fraction. For cursors, it's not so bad, so they are
	 * enabled.
	 *
	 * These can be enabled again when nuclear/atomic support lands.
	 */
	b->sprites_are_broken = 1;
	b->compositor = compositor;
	b->use_pixman = config->use_pixman;
	b->pageflip_timeout = config->pageflip_timeout;

	if (parse_gbm_format(config->gbm_format, GBM_FORMAT_XRGB8888, &b->gbm_format) < 0)
		goto err_compositor;

	if (config->seat_id)
		seat_id = config->seat_id;

	/* Check if we run drm-backend using weston-launch */
	compositor->launcher = weston_launcher_connect(compositor, config->tty,
						       seat_id, true);
	if (compositor->launcher == NULL) {
		weston_log("fatal: drm backend should be run "
			   "using weston-launch binary or as root\n");
		goto err_compositor;
	}

	b->udev = udev_new();
	if (b->udev == NULL) {
		weston_log("failed to initialize udev context\n");
		goto err_launcher;
	}

	b->session_listener.notify = session_notify;
	wl_signal_add(&compositor->session_signal, &b->session_listener);

	drm_device = find_primary_gpu(b, seat_id);
	if (drm_device == NULL) {
		weston_log("no drm device found\n");
		goto err_udev;
	}

	if (init_kms_caps(b) < 0) {
		weston_log("failed to initialize kms\n");
		goto err_udev_dev;
	}

	if (b->use_pixman) {
		if (init_pixman(b) < 0) {
			weston_log("failed to initialize pixman renderer\n");
			goto err_udev_dev;
		}
	} else {
		if (init_egl(b) < 0) {
			weston_log("failed to initialize egl\n");
			goto err_udev_dev;
		}
	}

	b->base.destroy = drm_destroy;
	b->base.restore = drm_restore;
	b->base.repaint_begin = drm_repaint_begin;
	b->base.repaint_flush = drm_repaint_flush;
	b->base.repaint_cancel = drm_repaint_cancel;

	weston_setup_vt_switch_bindings(compositor);

	wl_list_init(&b->plane_list);
	create_sprites(b);

	if (udev_input_init(&b->input,
			    compositor, b->udev, seat_id,
			    config->configure_device) < 0) {
		weston_log("failed to create input devices\n");
		goto err_sprite;
	}

	if (create_outputs(b, drm_device) < 0) {
		weston_log("failed to create output for %s\n", b->drm.filename);
		goto err_udev_input;
	}

	/* A this point we have some idea of whether or not we have a working
	 * cursor plane. */
	if (!b->cursors_are_broken)
		compositor->capabilities |= WESTON_CAP_CURSOR_PLANE;

	loop = wl_display_get_event_loop(compositor->wl_display);
	b->drm_source =
		wl_event_loop_add_fd(loop, b->drm.fd,
				     WL_EVENT_READABLE, on_drm_input, b);

	b->udev_monitor = udev_monitor_new_from_netlink(b->udev, "udev");
	if (b->udev_monitor == NULL) {
		weston_log("failed to initialize udev monitor\n");
		goto err_drm_source;
	}
	udev_monitor_filter_add_match_subsystem_devtype(b->udev_monitor,
							"drm", NULL);
	b->udev_drm_source =
		wl_event_loop_add_fd(loop,
				     udev_monitor_get_fd(b->udev_monitor),
				     WL_EVENT_READABLE, udev_drm_event, b);

	if (udev_monitor_enable_receiving(b->udev_monitor) < 0) {
		weston_log("failed to enable udev-monitor receiving\n");
		goto err_udev_monitor;
	}

	udev_device_unref(drm_device);

	weston_compositor_add_debug_binding(compositor, KEY_O,
					    planes_binding, b);
	weston_compositor_add_debug_binding(compositor, KEY_C,
					    planes_binding, b);
	weston_compositor_add_debug_binding(compositor, KEY_V,
					    planes_binding, b);
	weston_compositor_add_debug_binding(compositor, KEY_Q,
					    recorder_binding, b);
	weston_compositor_add_debug_binding(compositor, KEY_W,
					    renderer_switch_binding, b);

	if (compositor->renderer->import_dmabuf) {
		if (linux_dmabuf_setup(compositor) < 0)
			weston_log("Error: initializing dmabuf "
				   "support failed.\n");
	}

	compositor->backend = &b->base;

	ret = weston_plugin_api_register(compositor, WESTON_DRM_OUTPUT_API_NAME,
					 &api, sizeof(api));

	if (ret < 0) {
		weston_log("Failed to register output API.\n");
		goto err_udev_monitor;
	}

	return b;

err_udev_monitor:
	wl_event_source_remove(b->udev_drm_source);
	udev_monitor_unref(b->udev_monitor);
err_drm_source:
	wl_event_source_remove(b->drm_source);
err_udev_input:
	udev_input_destroy(&b->input);
err_sprite:
	if (b->gbm)
		gbm_device_destroy(b->gbm);
	destroy_sprites(b);
err_udev_dev:
	udev_device_unref(drm_device);
err_launcher:
	weston_launcher_destroy(compositor->launcher);
err_udev:
	udev_unref(b->udev);
err_compositor:
	weston_compositor_shutdown(compositor);
	free(b);
	return NULL;
}

static void
config_init_to_defaults(struct weston_drm_backend_config *config)
{
}

WL_EXPORT int
weston_backend_init(struct weston_compositor *compositor,
		    struct weston_backend_config *config_base)
{
	struct drm_backend *b;
	struct weston_drm_backend_config config = {{ 0, }};

	if (config_base == NULL ||
	    config_base->struct_version != WESTON_DRM_BACKEND_CONFIG_VERSION ||
	    config_base->struct_size > sizeof(struct weston_drm_backend_config)) {
		weston_log("drm backend config structure is invalid\n");
		return -1;
	}

	config_init_to_defaults(&config);
	memcpy(&config, config_base, config_base->struct_size);

	b = drm_backend_create(compositor, &config);
	if (b == NULL)
		return -1;

	return 0;
}