compositor-drm: Don't page flip before a mode is set
The function drm_output_start_repaint_loop() unconditionally issues a
page flip, even if the crtc for that output has not been enabled yet.
That causes the page flip to fail, and drm_output_repaint() is never
called.
Solve this by bypassing the initial page flip if the output needs a
mode set.
This has the caveat of affecting latency predictability for that first
frame and when a "driver" mode fullscreen surface causes a mode set.
However, on both cases the mode set would take an unpredictable amount
of time anyway.
https://bugs.freedesktop.org/show_bug.cgi?id=63812
https://bugs.freedesktop.org/show_bug.cgi?id=64183
diff --git a/src/compositor-drm.c b/src/compositor-drm.c
index bb8ea46..9dce809 100644
--- a/src/compositor-drm.c
+++ b/src/compositor-drm.c
@@ -37,6 +37,7 @@
#include <linux/input.h>
#include <assert.h>
#include <sys/mman.h>
+#include <time.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
@@ -52,6 +53,10 @@
#include "udev-seat.h"
#include "launcher-util.h"
+#ifndef DRM_CAP_TIMESTAMP_MONOTONIC
+#define DRM_CAP_TIMESTAMP_MONOTONIC 0x6
+#endif
+
static int option_current_mode = 0;
static char *output_name;
static char *output_mode;
@@ -114,6 +119,8 @@
int use_pixman;
uint32_t prev_state;
+
+ clockid_t clock;
};
struct drm_mode {
@@ -663,10 +670,19 @@
output_base->compositor;
uint32_t fb_id;
- if (output->current)
- fb_id = output->current->fb_id;
- else
- fb_id = output->original_crtc->buffer_id;
+ struct timespec ts;
+
+ if (!output->current) {
+ /* We can't page flip if there's no mode set */
+ uint32_t msec;
+
+ clock_gettime(compositor->clock, &ts);
+ msec = ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
+ weston_output_finish_frame(output_base, msec);
+ return;
+ }
+
+ fb_id = output->current->fb_id;
if (drmModePageFlip(compositor->drm.fd, output->crtc_id, fb_id,
DRM_MODE_PAGE_FLIP_EVENT, output) < 0) {
@@ -1184,7 +1200,8 @@
init_drm(struct drm_compositor *ec, struct udev_device *device)
{
const char *filename, *sysnum;
- int fd;
+ uint64_t cap;
+ int fd, ret;
sysnum = udev_device_get_sysnum(device);
if (sysnum)
@@ -1207,6 +1224,11 @@
ec->drm.fd = fd;
+ ret = drmGetCap(fd, DRM_CAP_TIMESTAMP_MONOTONIC, &cap);
+ if (ret == 0 && cap == 1)
+ ec->clock = CLOCK_MONOTONIC;
+ else
+ ec->clock = CLOCK_REALTIME;
return 0;
}