src/gstamlv4l2allocator.c

/* GStreamer
 * Copyright (C) 2022 <xuesong.jiang@amlogic.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
 * Boston, MA 02110-1335, USA.
 */

#include "config.h"

#include "ext/videodev2.h"

#include "gstamlv4l2object.h"
#include "gstamlv4l2allocator.h"

#include <gst/allocators/gstdmabuf.h>

#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <stdio.h>

#define GST_AML_V4L2_MEMORY_TYPE "V4l2Memory"

#define gst_aml_v4l2_allocator_parent_class parent_class
G_DEFINE_TYPE(GstAmlV4l2Allocator, gst_aml_v4l2_allocator, GST_TYPE_ALLOCATOR);

GST_DEBUG_CATEGORY_STATIC(amlv4l2allocator_debug);
#define GST_CAT_DEFAULT amlv4l2allocator_debug

#define UNSET_QUEUED(buffer) \
    ((buffer).flags &= ~(V4L2_BUF_FLAG_QUEUED | V4L2_BUF_FLAG_DONE))

#define SET_QUEUED(buffer) ((buffer).flags |= V4L2_BUF_FLAG_QUEUED)

#define IS_QUEUED(buffer) \
    ((buffer).flags & (V4L2_BUF_FLAG_QUEUED | V4L2_BUF_FLAG_DONE))

enum
{
  GROUP_RELEASED,
  LAST_SIGNAL
};

static guint gst_aml_v4l2_allocator_signals[LAST_SIGNAL] = {0};

static void gst_aml_v4l2_allocator_dump_es_buf(GstAmlV4l2Allocator *allocator, GstAmlV4l2MemoryGroup *group)
{
    const gchar *dump_dir = NULL;
    gchar *full_file_name = NULL;
    FILE *out = NULL;

    dump_dir = g_getenv("GST_AML_DUMP_AML_V4L2_ES_BUF_DIR");
    if (G_LIKELY(dump_dir == NULL))
        return;

    if (allocator->obj->type != V4L2_BUF_TYPE_VIDEO_OUTPUT && allocator->obj->type != V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
        return;

    GST_DEBUG_OBJECT(allocator, "assert ok start dump");
    full_file_name = g_strdup_printf("%s" G_DIR_SEPARATOR_S "amlv4l2_es.bin", dump_dir);
    if ((out = fopen(full_file_name, "ab")))
    {
        GST_DEBUG_OBJECT(allocator, "open dir ok");
        GstMapInfo map;
        memset(&map, 0, sizeof(GstMapInfo));
        for (int i = 0; i < group->n_mem; i++)
        {
            if (gst_memory_map(group->mem[i], &map, GST_MAP_READ))
            {
                GST_DEBUG_OBJECT(allocator, "es ts:%llu dump_size:%d,v4l2_buf_byteused:%d,%d",
                                 group->buffer.timestamp.tv_sec * 1000000000ULL + group->buffer.timestamp.tv_usec * 1000,
                                 map.size,
                                 group->buffer.bytesused, group->planes[0].bytesused);
                fwrite(map.data, map.size, 1, out);
                gst_memory_unmap(group->mem[i], &map);
            }
        }
        fclose(out);
        out = NULL;
    }
    g_free(full_file_name);
}

static void gst_aml_v4l2_allocator_release(GstAmlV4l2Allocator *allocator,
    GstAmlV4l2Memory *mem);

static const gchar *
memory_type_to_str (guint32 memory)
{
  switch (memory)
  {
    case V4L2_MEMORY_MMAP:
      return "mmap";
    case V4L2_MEMORY_USERPTR:
      return "userptr";
    case V4L2_MEMORY_DMABUF:
      return "dmabuf";
    default:
      return "unknown";
  }
}

/*************************************/
/* GstAmlV4lMemory implementation */
/*************************************/

static gpointer
_v4l2mem_map(GstAmlV4l2Memory *mem, gsize maxsize, GstMapFlags flags)
{
  gpointer data = NULL;

  switch (mem->group->buffer.memory)
  {
    case V4L2_MEMORY_MMAP:
    case V4L2_MEMORY_USERPTR:
      data = mem->data;
      break;
    case V4L2_MEMORY_DMABUF:
      /* v4l2 dmabuf memory are not shared with downstream */
      g_assert_not_reached ();
      break;
    default:
      GST_WARNING ("Unknown memory type %i", mem->group->buffer.memory);
      break;
  }
  return data;
}

static gboolean
_v4l2mem_unmap(GstAmlV4l2Memory *mem)
{
  gboolean ret = FALSE;

  switch (mem->group->buffer.memory)
  {
    case V4L2_MEMORY_MMAP:
    case V4L2_MEMORY_USERPTR:
      ret = TRUE;
      break;
    case V4L2_MEMORY_DMABUF:
      /* v4l2 dmabuf memory are not share with downstream */
      g_assert_not_reached ();
      break;
    default:
      GST_WARNING ("Unknown memory type %i", mem->group->buffer.memory);
      break;
  }
  return ret;
}

static gboolean
_v4l2mem_dispose(GstAmlV4l2Memory *mem)
{
  GstAmlV4l2Allocator *allocator = (GstAmlV4l2Allocator *)mem->mem.allocator;
  GstAmlV4l2MemoryGroup *group = mem->group;
  gboolean ret;

  if (group->mem[mem->plane])
  {
    /* We may have a dmabuf, replace it with returned original memory */
    group->mem[mem->plane] = gst_memory_ref ((GstMemory *) mem);
    gst_aml_v4l2_allocator_release(allocator, mem);
    ret = FALSE;
  }
  else
  {
    gst_object_ref (allocator);
    ret = TRUE;
  }

  return ret;
}

static inline GstAmlV4l2Memory *
_v4l2mem_new (GstMemoryFlags flags, GstAllocator * allocator,
    GstMemory * parent, gsize maxsize, gsize align, gsize offset, gsize size,
    gint plane, gpointer data, int dmafd, GstAmlV4l2MemoryGroup *group)
{
  GstAmlV4l2Memory *mem;

  mem = g_slice_new0 (GstAmlV4l2Memory);
  gst_memory_init (GST_MEMORY_CAST (mem),
      flags, allocator, parent, maxsize, align, offset, size);

  if (parent == NULL)
    mem->mem.mini_object.dispose =
        (GstMiniObjectDisposeFunction) _v4l2mem_dispose;

  mem->plane = plane;
  mem->data = data;
  mem->dmafd = dmafd;
  mem->group = group;

  return mem;
}

static GstAmlV4l2Memory *
_v4l2mem_share(GstAmlV4l2Memory *mem, gssize offset, gsize size)
{
  GstAmlV4l2Memory *sub;
  GstMemory *parent;

  /* find the real parent */
  if ((parent = mem->mem.parent) == NULL)
    parent = (GstMemory *) mem;

  if (size == -1)
    size = mem->mem.size - offset;

  /* the shared memory is always readonly */
  sub = _v4l2mem_new (GST_MINI_OBJECT_FLAGS (parent) |
      GST_MINI_OBJECT_FLAG_LOCK_READONLY, mem->mem.allocator, parent,
      mem->mem.maxsize, mem->mem.align, offset, size, mem->plane, mem->data,
      -1, mem->group);

  return sub;
}

static gboolean
_v4l2mem_is_span(GstAmlV4l2Memory *mem1, GstAmlV4l2Memory *mem2, gsize *offset)
{
  if (offset)
    *offset = mem1->mem.offset - mem1->mem.parent->offset;

  /* and memory is contiguous */
  return mem1->mem.offset + mem1->mem.size == mem2->mem.offset;
}

gboolean
gst_aml_is_v4l2_memory(GstMemory *mem)
{
  return gst_memory_is_type(mem, GST_AML_V4L2_MEMORY_TYPE);
}

GQuark
gst_aml_v4l2_memory_quark(void)
{
  static GQuark quark = 0;

  if (quark == 0)
      quark = g_quark_from_string ("GstAmlV4l2Memory");

  return quark;
}

/*************************************/
/* GstAmlV4l2MemoryGroup implementation */
/*************************************/

static void
gst_aml_v4l2_memory_group_free(GstAmlV4l2MemoryGroup *group)
{
  gint i;

  for (i = 0; i < group->n_mem; i++)
  {
    GstMemory *mem = group->mem[i];
    group->mem[i] = NULL;
    if (mem)
      gst_memory_unref (mem);
  }

  g_slice_free(GstAmlV4l2MemoryGroup, group);
}

static GstAmlV4l2MemoryGroup *
gst_aml_v4l2_memory_group_new(GstAmlV4l2Allocator *allocator, guint32 index)
{
  GstAmlV4l2Object *obj = allocator->obj;
  guint32 memory = allocator->memory;
  struct v4l2_format *format = &obj->format;
  GstAmlV4l2MemoryGroup *group;
  gsize img_size, buf_size;

  group = g_slice_new0 (GstAmlV4l2MemoryGroup);

  group->buffer.type = format->type;
  group->buffer.index = index;
  group->buffer.memory = memory;

  if (V4L2_TYPE_IS_MULTIPLANAR(format->type))
  {
    group->n_mem = group->buffer.length = format->fmt.pix_mp.num_planes;
    group->buffer.m.planes = group->planes;
  }
  else
  {
    group->n_mem = 1;
  }

  if (obj->ioctl (obj->video_fd, VIDIOC_QUERYBUF, &group->buffer) < 0)
    goto querybuf_failed;

  if (group->buffer.index != index)
  {
    GST_ERROR_OBJECT (allocator, "Buffer index returned by VIDIOC_QUERYBUF "
        "didn't match, this indicate the presence of a bug in your driver or "
        "libv4l2");
    g_slice_free (GstAmlV4l2MemoryGroup, group);
    return NULL;
  }

  /* Check that provided size matches the format we have negotiation. Failing
   * there usually means a driver of libv4l bug. */
  if (V4L2_TYPE_IS_MULTIPLANAR(obj->type))
  {
    gint i;

    for (i = 0; i < group->n_mem; i++)
    {
      img_size = obj->format.fmt.pix_mp.plane_fmt[i].sizeimage;
      buf_size = group->planes[i].length;
      if (buf_size < img_size)
        goto buffer_too_short;
    }
  }
  else
  {
    img_size = obj->format.fmt.pix.sizeimage;
    buf_size = group->buffer.length;
    if (buf_size < img_size)
      goto buffer_too_short;
  }

  /* We save non planar buffer information into the multi-planar plane array
   * to avoid duplicating the code later */
  if (!V4L2_TYPE_IS_MULTIPLANAR(format->type))
  {
    group->planes[0].bytesused = group->buffer.bytesused;
    group->planes[0].length = group->buffer.length;
    group->planes[0].data_offset = 0;
    g_assert (sizeof (group->planes[0].m) == sizeof (group->buffer.m));
    memcpy (&group->planes[0].m, &group->buffer.m, sizeof (group->buffer.m));
  }

  GST_LOG_OBJECT (allocator, "Got %s buffer", memory_type_to_str (memory));
  GST_LOG_OBJECT (allocator, "  index:     %u", group->buffer.index);
  GST_LOG_OBJECT (allocator, "  type:      %d", group->buffer.type);
  GST_LOG_OBJECT (allocator, "  flags:     %08x", group->buffer.flags);
  GST_LOG_OBJECT (allocator, "  field:     %d", group->buffer.field);
  GST_LOG_OBJECT (allocator, "  memory:    %d", group->buffer.memory);
  GST_LOG_OBJECT (allocator, "  planes:    %d", group->n_mem);

#ifndef GST_DISABLE_GST_DEBUG
  if (memory == V4L2_MEMORY_MMAP)
  {
    gint i;
    for (i = 0; i < group->n_mem; i++)
    {
      GST_LOG_OBJECT (allocator,
          "  [%u] bytesused: %u, length: %u, offset: %u", i,
          group->planes[i].bytesused, group->planes[i].length,
          group->planes[i].data_offset);
      GST_LOG_OBJECT (allocator, "  [%u] MMAP offset:  %u", i,
          group->planes[i].m.mem_offset);
    }
  }
#endif

  return group;

querybuf_failed:
  {
    GST_ERROR ("error querying buffer %d: %s", index, g_strerror (errno));
    goto failed;
  }
buffer_too_short:
  {
    GST_ERROR ("buffer size %" G_GSIZE_FORMAT
        " is smaller then negotiated size %" G_GSIZE_FORMAT
        ", this is usually the result of a bug in the v4l2 driver or libv4l.",
        buf_size, img_size);
    goto failed;
  }
failed:
  gst_aml_v4l2_memory_group_free(group);
  return NULL;
}


/*************************************/
/* GstV4lAllocator implementation    */
/*************************************/

static void
gst_aml_v4l2_allocator_release(GstAmlV4l2Allocator *allocator, GstAmlV4l2Memory *mem)
{
  GstAmlV4l2MemoryGroup *group = mem->group;

  GST_LOG_OBJECT (allocator, "plane %i of buffer %u released",
      mem->plane, group->buffer.index);

  switch (allocator->memory)
  {
    case V4L2_MEMORY_DMABUF:
      close (mem->dmafd);
      mem->dmafd = -1;
      break;
    case V4L2_MEMORY_USERPTR:
      mem->data = NULL;
      break;
    default:
      break;
  }

  /* When all memory are back, put the group back in the free queue */
  if (g_atomic_int_dec_and_test(&group->mems_allocated))
  {
    GST_LOG_OBJECT (allocator, "buffer %u released", group->buffer.index);
    gst_atomic_queue_push (allocator->free_queue, group);
    g_signal_emit (allocator, gst_aml_v4l2_allocator_signals[GROUP_RELEASED], 0);
  }

  /* Keep last, allocator may be freed after this call */
  g_object_unref (allocator);
}

static void
gst_aml_v4l2_allocator_free(GstAllocator *gallocator, GstMemory *gmem)
{
  GstAmlV4l2Allocator *allocator = (GstAmlV4l2Allocator *)gallocator;
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2Memory *mem = (GstAmlV4l2Memory *)gmem;
  GstAmlV4l2MemoryGroup *group = mem->group;

  /* Only free unparented memory */
  if (mem->mem.parent == NULL)
  {
    GST_LOG_OBJECT (allocator, "freeing plane %i of buffer %u",
        mem->plane, group->buffer.index);

    if (allocator->memory == V4L2_MEMORY_MMAP)
    {
      if (mem->data)
        obj->munmap (mem->data, group->planes[mem->plane].length);
    }

    /* This apply for both mmap with expbuf, and dmabuf imported memory */
    if (mem->dmafd >= 0)
      close (mem->dmafd);
  }

  g_slice_free (GstAmlV4l2Memory, mem);
}

static void
gst_aml_v4l2_allocator_dispose(GObject *obj)
{
  GstAmlV4l2Allocator *allocator = (GstAmlV4l2Allocator *)obj;
  gint i;

  GST_LOG_OBJECT (obj, "called");

  for (i = 0; i < allocator->count; i++)
  {
    GstAmlV4l2MemoryGroup *group = allocator->groups[i];
    allocator->groups[i] = NULL;
    if (group)
      gst_aml_v4l2_memory_group_free(group);
  }

  G_OBJECT_CLASS (parent_class)->dispose (obj);
}

static void
gst_aml_v4l2_allocator_finalize(GObject *obj)
{
  GstAmlV4l2Allocator *allocator = (GstAmlV4l2Allocator *)obj;

  GST_LOG_OBJECT (obj, "called");

  gst_atomic_queue_unref (allocator->free_queue);
  gst_object_unref (allocator->obj->element);

  G_OBJECT_CLASS (parent_class)->finalize (obj);
}

static void
gst_aml_v4l2_allocator_class_init(GstAmlV4l2AllocatorClass *klass)
{
  GObjectClass *object_class;
  GstAllocatorClass *allocator_class;

  allocator_class = (GstAllocatorClass *) klass;
  object_class = (GObjectClass *) klass;

  allocator_class->alloc = NULL;
  allocator_class->free = gst_aml_v4l2_allocator_free;

  object_class->dispose = gst_aml_v4l2_allocator_dispose;
  object_class->finalize = gst_aml_v4l2_allocator_finalize;

  gst_aml_v4l2_allocator_signals[GROUP_RELEASED] = g_signal_new("group-released",
                                                                G_TYPE_FROM_CLASS(object_class), G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL,
                                                                G_TYPE_NONE, 0);

  GST_DEBUG_CATEGORY_INIT(amlv4l2allocator_debug, "v4l2allocator", 0,
                          "V4L2 Allocator");
}

static void
gst_aml_v4l2_allocator_init(GstAmlV4l2Allocator *allocator)
{
  GstAllocator *alloc = GST_ALLOCATOR_CAST (allocator);

  alloc->mem_type = GST_AML_V4L2_MEMORY_TYPE;
  alloc->mem_map = (GstMemoryMapFunction) _v4l2mem_map;
  alloc->mem_unmap = (GstMemoryUnmapFunction) _v4l2mem_unmap;
  alloc->mem_share = (GstMemoryShareFunction) _v4l2mem_share;
  alloc->mem_is_span = (GstMemoryIsSpanFunction) _v4l2mem_is_span;
  /* Use the default, fallback copy function */

  allocator->free_queue = gst_atomic_queue_new (VIDEO_MAX_FRAME);

  GST_OBJECT_FLAG_SET (allocator, GST_ALLOCATOR_FLAG_CUSTOM_ALLOC);
}

#define GST_AML_V4L2_ALLOCATOR_PROBE(obj, type)                            \
  gst_aml_v4l2_allocator_probe((obj), V4L2_MEMORY_##type,                \
                               GST_V4L2_ALLOCATOR_FLAG_##type##_REQBUFS, \
                               GST_V4L2_ALLOCATOR_FLAG_##type##_CREATE_BUFS)
static guint32
gst_aml_v4l2_allocator_probe(GstAmlV4l2Allocator *allocator, guint32 memory,
                           guint32 breq_flag, guint32 bcreate_flag)
{
  GstAmlV4l2Object *obj = allocator->obj;
  struct v4l2_requestbuffers breq = { 0 };
  guint32 flags = 0;

  breq.type = obj->type;
  breq.count = 0;
  breq.memory = memory;

  if (obj->ioctl(obj->video_fd, VIDIOC_REQBUFS, &breq) == 0)
  {
    struct v4l2_create_buffers bcreate = { 0 };

    flags |= breq_flag;

    bcreate.memory = memory;
    bcreate.format = obj->format;

    if ((obj->ioctl (obj->video_fd, VIDIOC_CREATE_BUFS, &bcreate) == 0))
      flags |= bcreate_flag;
  }

  if (breq.capabilities & V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS)
  {
    flags |= GST_V4L2_ALLOCATOR_FLAG_SUPPORTS_ORPHANED_BUFS;
    GST_DEBUG_OBJECT(allocator, "v4l2 support GST_V4L2_ALLOCATOR_FLAG_SUPPORTS_ORPHANED_BUFS");
  }

  return flags;
}

static GstAmlV4l2MemoryGroup *
gst_aml_v4l2_allocator_create_buf(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2Object *obj = allocator->obj;
  struct v4l2_create_buffers bcreate = { 0 };
  GstAmlV4l2MemoryGroup *group = NULL;

  GST_OBJECT_LOCK (allocator);

  if (!g_atomic_int_get (&allocator->active))
    goto done;

  if (GST_AML_V4L2_ALLOCATOR_IS_ORPHANED(allocator))
    goto orphaned_bug;

  bcreate.memory = allocator->memory;
  bcreate.format = obj->format;
  bcreate.count = 1;

  if (!allocator->can_allocate)
    goto done;

  if (obj->ioctl (obj->video_fd, VIDIOC_CREATE_BUFS, &bcreate) < 0)
    goto create_bufs_failed;

  if (allocator->groups[bcreate.index] != NULL)
    goto create_bufs_bug;

  group = gst_aml_v4l2_memory_group_new(allocator, bcreate.index);

  if (group)
  {
    allocator->groups[bcreate.index] = group;
    allocator->count++;
  }

done:
  GST_OBJECT_UNLOCK (allocator);
  return group;

orphaned_bug:
  {
    GST_ERROR_OBJECT (allocator, "allocator was orphaned, "
        "not creating new buffers");
    goto done;
  }
create_bufs_failed:
  {
    GST_WARNING_OBJECT (allocator, "error creating a new buffer: %s",
        g_strerror (errno));
    goto done;
  }
create_bufs_bug:
  {
    GST_ERROR_OBJECT (allocator, "created buffer has already used buffer "
        "index %i, this means there is an bug in your driver or libv4l2",
        bcreate.index);
    goto done;
  }
}

static GstAmlV4l2MemoryGroup *
gst_aml_v4l2_allocator_alloc(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2MemoryGroup *group;

  if (!g_atomic_int_get (&allocator->active))
    return NULL;

  group = gst_atomic_queue_pop (allocator->free_queue);

  if (group == NULL)
  {
    if (allocator->can_allocate)
    {
      group = gst_aml_v4l2_allocator_create_buf(allocator);

      /* Don't hammer on CREATE_BUFS */
      if (group == NULL)
        allocator->can_allocate = FALSE;
    }
  }

  return group;
}

static void
gst_aml_v4l2_allocator_reset_size(GstAmlV4l2Allocator *allocator,
                                  GstAmlV4l2MemoryGroup *group)
{
  gint i;
  for (i = 0; i < group->n_mem; i++)
  {
    group->mem[i]->maxsize = group->planes[i].length;
    group->mem[i]->offset = 0;
    group->mem[i]->size = group->planes[i].length;
  }
}

static void
_cleanup_failed_alloc(GstAmlV4l2Allocator *allocator, GstAmlV4l2MemoryGroup *group)
{
  if (group->mems_allocated > 0)
  {
    gint i;
    /* If one or more mmap worked, we need to unref the memory, otherwise
     * they will keep a ref on the allocator and leak it. This will put back
     * the group into the free_queue */
    for (i = 0; i < group->n_mem; i++)
      gst_memory_unref (group->mem[i]);
  }
  else
  {
    /* Otherwise, group has to be on free queue for _stop() to work */
    gst_atomic_queue_push (allocator->free_queue, group);
  }
}

GstAmlV4l2Allocator *
gst_aml_v4l2_allocator_new(GstObject *parent, GstAmlV4l2Object *v4l2object)
{
  GstAmlV4l2Allocator *allocator;
  guint32 flags = 0;
  gchar *name, *parent_name;

  parent_name = gst_object_get_name (parent);
  name = g_strconcat (parent_name, ":allocator", NULL);
  g_free (parent_name);

  allocator = g_object_new(GST_TYPE_AML_V4L2_ALLOCATOR, "name", name, NULL);
  gst_object_ref_sink (allocator);
  g_free (name);

  /* Save everything */
  allocator->obj = v4l2object;

  /* Keep a ref on the element so obj does not disappear */
  gst_object_ref (allocator->obj->element);

  flags |= GST_AML_V4L2_ALLOCATOR_PROBE(allocator, MMAP);
  flags |= GST_AML_V4L2_ALLOCATOR_PROBE(allocator, USERPTR);
  flags |= GST_AML_V4L2_ALLOCATOR_PROBE(allocator, DMABUF);


  if (flags == 0)
  {
    /* Drivers not ported from videobuf to videbuf2 don't allow freeing buffers
     * using REQBUFS(0). This is a workaround to still support these drivers,
     * which are known to have MMAP support. */
    GST_WARNING_OBJECT (allocator, "Could not probe supported memory type, "
        "assuming MMAP is supported, this is expected for older drivers not "
        " yet ported to videobuf2 framework");
    flags = GST_V4L2_ALLOCATOR_FLAG_MMAP_REQBUFS;
  }

  GST_OBJECT_FLAG_SET (allocator, flags);

  return allocator;
}

guint
gst_aml_v4l2_allocator_start(GstAmlV4l2Allocator *allocator, guint32 count,
                                   guint32 memory)
{
  GstAmlV4l2Object *obj = allocator->obj;
  struct v4l2_requestbuffers breq = { count, obj->type, memory };
  gboolean can_allocate;
  gint i;

  g_return_val_if_fail (count != 0, 0);

  GST_OBJECT_LOCK (allocator);

  if (g_atomic_int_get (&allocator->active))
    goto already_active;

  if (GST_AML_V4L2_ALLOCATOR_IS_ORPHANED(allocator))
    goto orphaned;

  if (obj->ioctl (obj->video_fd, VIDIOC_REQBUFS, &breq) < 0)
    goto reqbufs_failed;

  if (breq.count < 1)
    goto out_of_memory;

  switch (memory)
  {
    case V4L2_MEMORY_MMAP:
      can_allocate = GST_AML_V4L2_ALLOCATOR_CAN_ALLOCATE(allocator, MMAP);
      break;
    case V4L2_MEMORY_USERPTR:
      can_allocate = GST_AML_V4L2_ALLOCATOR_CAN_ALLOCATE(allocator, USERPTR);
      break;
    case V4L2_MEMORY_DMABUF:
      can_allocate = GST_AML_V4L2_ALLOCATOR_CAN_ALLOCATE(allocator, DMABUF);
      break;
    default:
      can_allocate = FALSE;
      break;
  }

  GST_DEBUG_OBJECT (allocator, "allocated %u %s buffers out of %u requested",
      breq.count, memory_type_to_str (memory), count);

  allocator->can_allocate = can_allocate;
  allocator->count = breq.count;
  allocator->memory = memory;

  /* Create memory groups */
  for (i = 0; i < allocator->count; i++)
  {
    allocator->groups[i] = gst_aml_v4l2_memory_group_new(allocator, i);
    if (allocator->groups[i] == NULL)
      goto error;

    gst_atomic_queue_push (allocator->free_queue, allocator->groups[i]);
  }

  g_atomic_int_set (&allocator->active, TRUE);

done:
  GST_OBJECT_UNLOCK (allocator);
  return breq.count;

already_active:
  {
    GST_ERROR_OBJECT (allocator, "allocator already active");
    goto error;
  }
orphaned:
  {
    GST_ERROR_OBJECT (allocator, "allocator was orphaned");
    goto error;
  }
reqbufs_failed:
  {
    GST_ERROR_OBJECT (allocator,
        "error requesting %d buffers: %s", count, g_strerror (errno));
    goto error;
  }
out_of_memory:
  {
    GST_ERROR_OBJECT (allocator, "Not enough memory to allocate buffers");
    goto error;
  }
error:
  {
    breq.count = 0;
    goto done;
  }
}

GstAmlV4l2Return
gst_aml_v4l2_allocator_stop(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2Object *obj = allocator->obj;
  struct v4l2_requestbuffers breq = { 0, obj->type, allocator->memory };
  gint i = 0;
  GstAmlV4l2Return ret = GST_AML_V4L2_OK;

  GST_DEBUG_OBJECT (allocator, "stop allocator");

  GST_OBJECT_LOCK (allocator);

  if (!g_atomic_int_get (&allocator->active))
    goto done;

  if (gst_atomic_queue_length(allocator->free_queue) != allocator->count)
  {
    GST_DEBUG_OBJECT (allocator, "allocator is still in use");
    ret = GST_AML_V4L2_BUSY;
    goto done;
  }

  while (gst_atomic_queue_pop(allocator->free_queue))
  {
    /* nothing */
  };

  for (i = 0; i < allocator->count; i++)
  {
    GstAmlV4l2MemoryGroup *group = allocator->groups[i];
    allocator->groups[i] = NULL;
    if (group)
      gst_aml_v4l2_memory_group_free(group);
  }

  if (!GST_AML_V4L2_ALLOCATOR_IS_ORPHANED(allocator))
  {
    /* Not all drivers support rebufs(0), so warn only */
    if (obj->ioctl (obj->video_fd, VIDIOC_REQBUFS, &breq) < 0)
      GST_WARNING_OBJECT (allocator,
          "error releasing buffers buffers: %s", g_strerror (errno));
  }

  allocator->count = 0;

  g_atomic_int_set (&allocator->active, FALSE);

done:
  GST_OBJECT_UNLOCK (allocator);
  return ret;
}

gboolean
gst_aml_v4l2_allocator_orphan(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2Object *obj = allocator->obj;
  struct v4l2_requestbuffers breq = { 0, obj->type, allocator->memory };

  if (!GST_AML_V4L2_ALLOCATOR_CAN_ORPHAN_BUFS(allocator))
    return FALSE;

  GST_OBJECT_FLAG_SET (allocator, GST_V4L2_ALLOCATOR_FLAG_ORPHANED);

  if (obj->ioctl(obj->video_fd, VIDIOC_REQBUFS, &breq) < 0)
  {
    GST_ERROR_OBJECT (allocator,
        "error orphaning buffers buffers: %s", g_strerror (errno));
    return FALSE;
  }

  return TRUE;
}

GstAmlV4l2MemoryGroup *
gst_aml_v4l2_allocator_alloc_mmap(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2MemoryGroup *group;
  gint i;

  g_return_val_if_fail (allocator->memory == V4L2_MEMORY_MMAP, NULL);

  group = gst_aml_v4l2_allocator_alloc(allocator);

  if (group == NULL)
    return NULL;

  for (i = 0; i < group->n_mem; i++)
  {
    if (group->mem[i] == NULL)
    {
      gpointer data;
      data = obj->mmap (NULL, group->planes[i].length, PROT_READ | PROT_WRITE,
          MAP_SHARED, obj->video_fd, group->planes[i].m.mem_offset);

      if (data == MAP_FAILED)
        goto mmap_failed;

      GST_LOG_OBJECT (allocator,
          "mmap buffer length %d, data offset %d, plane %d",
          group->planes[i].length, group->planes[i].data_offset, i);

      group->mem[i] = (GstMemory *) _v4l2mem_new (0, GST_ALLOCATOR (allocator),
          NULL, group->planes[i].length, 0, 0, group->planes[i].length, i, data,
          -1, group);
    }
    else
    {
      /* Take back the allocator reference */
      gst_object_ref (allocator);
    }

    group->mems_allocated++;
  }

  /* Ensure group size. Unlike GST, v4l2 have size (bytesused) initially set
   * to 0. As length might be bigger then the expected size exposed in the
   * format, we simply set bytesused initially and reset it here for
   * simplicity */
  gst_aml_v4l2_allocator_reset_size(allocator, group);

  return group;

mmap_failed:
  {
    GST_ERROR_OBJECT (allocator, "Failed to mmap buffer: %s",
        g_strerror (errno));
    _cleanup_failed_alloc (allocator, group);
    return NULL;
  }
}

GstAmlV4l2MemoryGroup *
gst_aml_v4l2_allocator_alloc_dmabuf(GstAmlV4l2Allocator *allocator,
    GstAllocator * dmabuf_allocator)
{
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2MemoryGroup *group;
  gint i;

  g_return_val_if_fail (allocator->memory == V4L2_MEMORY_MMAP, NULL);

  group = gst_aml_v4l2_allocator_alloc(allocator);

  if (group == NULL)
    return NULL;

  for (i = 0; i < group->n_mem; i++)
  {
    GstAmlV4l2Memory *mem;
    GstMemory *dma_mem;

    if (group->mem[i] == NULL)
    {
      struct v4l2_exportbuffer expbuf = { 0 };

      expbuf.type = obj->type;
      expbuf.index = group->buffer.index;
      expbuf.plane = i;
      expbuf.flags = O_CLOEXEC | O_RDWR;

      if (obj->ioctl (obj->video_fd, VIDIOC_EXPBUF, &expbuf) < 0)
        goto expbuf_failed;

      GST_LOG_OBJECT (allocator, "exported DMABUF as fd %i plane %d",
          expbuf.fd, i);

      group->mem[i] = (GstMemory *) _v4l2mem_new (0, GST_ALLOCATOR (allocator),
          NULL, group->planes[i].length, 0, group->planes[i].data_offset,
          group->planes[i].length - group->planes[i].data_offset, i, NULL,
          expbuf.fd, group);
    }
    else
    {
      /* Take back the allocator reference */
      gst_object_ref (allocator);
    }

    group->mems_allocated++;

    g_assert(gst_aml_is_v4l2_memory(group->mem[i]));
    mem = (GstAmlV4l2Memory *)group->mem[i];

    dma_mem = gst_fd_allocator_alloc (dmabuf_allocator, mem->dmafd,
        group->planes[i].length, GST_FD_MEMORY_FLAG_DONT_CLOSE);
    gst_memory_resize (dma_mem, group->planes[i].data_offset,
        group->planes[i].length - group->planes[i].data_offset);

    gst_mini_object_set_qdata (GST_MINI_OBJECT (dma_mem),
                                GST_AML_V4L2_MEMORY_QUARK, mem, (GDestroyNotify)gst_memory_unref);

    group->mem[i] = dma_mem;
  }

  gst_aml_v4l2_allocator_reset_size(allocator, group);

  return group;

expbuf_failed:
  {
    GST_ERROR_OBJECT (allocator, "Failed to export DMABUF: %s",
        g_strerror (errno));
    goto cleanup;
  }
cleanup:
  {
    _cleanup_failed_alloc (allocator, group);
    return NULL;
  }
}

static void
gst_aml_v4l2_allocator_clear_dmabufin(GstAmlV4l2Allocator *allocator,
    GstAmlV4l2MemoryGroup *group)
{
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2Memory *mem;
  gint i;

  g_return_if_fail (allocator->memory == V4L2_MEMORY_DMABUF);

  for (i = 0; i < group->n_mem; i++)
  {

    mem = (GstAmlV4l2Memory *)group->mem[i];

    GST_LOG_OBJECT (allocator, "[%i] clearing DMABUF import, fd %i plane %d",
        group->buffer.index, mem->dmafd, i);

    /* Update memory */
    mem->mem.maxsize = 0;
    mem->mem.offset = 0;
    mem->mem.size = 0;
    mem->dmafd = -1;

    /* Update v4l2 structure */
    group->planes[i].length = 0;
    group->planes[i].bytesused = 0;
    group->planes[i].m.fd = -1;
    group->planes[i].data_offset = 0;
  }

  if (!V4L2_TYPE_IS_MULTIPLANAR(obj->type))
  {
    group->buffer.bytesused = 0;
    group->buffer.length = 0;
    group->buffer.m.fd = -1;
  }
}

GstAmlV4l2MemoryGroup *
gst_aml_v4l2_allocator_alloc_dmabufin(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2MemoryGroup *group;
  gint i;

  g_return_val_if_fail (allocator->memory == V4L2_MEMORY_DMABUF, NULL);

  group = gst_aml_v4l2_allocator_alloc(allocator);

  if (group == NULL)
    return NULL;

  GST_LOG_OBJECT (allocator, "allocating empty DMABUF import group");

  for (i = 0; i < group->n_mem; i++)
  {
    if (group->mem[i] == NULL)
    {
      group->mem[i] = (GstMemory *) _v4l2mem_new (0, GST_ALLOCATOR (allocator),
          NULL, 0, 0, 0, 0, i, NULL, -1, group);
    }
    else
    {
      /* Take back the allocator reference */
      gst_object_ref (allocator);
    }

    group->mems_allocated++;
  }

  gst_aml_v4l2_allocator_clear_dmabufin(allocator, group);

  return group;
}

static void
gst_aml_v4l2_allocator_clear_userptr(GstAmlV4l2Allocator *allocator,
    GstAmlV4l2MemoryGroup *group)
{
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2Memory *mem;
  gint i;

  g_return_if_fail (allocator->memory == V4L2_MEMORY_USERPTR);

  for (i = 0; i < group->n_mem; i++)
  {
    mem = (GstAmlV4l2Memory *)group->mem[i];

    GST_LOG_OBJECT (allocator, "[%i] clearing USERPTR %p plane %d size %"
        G_GSIZE_FORMAT, group->buffer.index, mem->data, i, mem->mem.size);

    mem->mem.maxsize = 0;
    mem->mem.size = 0;
    mem->data = NULL;

    group->planes[i].length = 0;
    group->planes[i].bytesused = 0;
    group->planes[i].m.userptr = 0;
  }

  if (!V4L2_TYPE_IS_MULTIPLANAR(obj->type))
  {
    group->buffer.bytesused = 0;
    group->buffer.length = 0;
    group->buffer.m.userptr = 0;
  }
}

GstAmlV4l2MemoryGroup *
gst_aml_v4l2_allocator_alloc_userptr(GstAmlV4l2Allocator *allocator)
{
  GstAmlV4l2MemoryGroup *group;
  gint i;

  g_return_val_if_fail (allocator->memory == V4L2_MEMORY_USERPTR, NULL);

  group = gst_aml_v4l2_allocator_alloc (allocator);

  if (group == NULL)
    return NULL;

  GST_LOG_OBJECT (allocator, "allocating empty USERPTR group");

  for (i = 0; i < group->n_mem; i++)
  {

    if (group->mem[i] == NULL)
    {
      group->mem[i] = (GstMemory *) _v4l2mem_new (0, GST_ALLOCATOR (allocator),
          NULL, 0, 0, 0, 0, i, NULL, -1, group);
    }
    else
    {
      /* Take back the allocator reference */
      gst_object_ref (allocator);
    }

    group->mems_allocated++;
  }

  gst_aml_v4l2_allocator_clear_userptr(allocator, group);

  return group;
}

gboolean
gst_aml_v4l2_allocator_import_dmabuf(GstAmlV4l2Allocator *allocator,
    GstAmlV4l2MemoryGroup *group, gint n_mem, GstMemory **dma_mem)
{
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2Memory *mem;
  gint i;

  g_return_val_if_fail (allocator->memory == V4L2_MEMORY_DMABUF, FALSE);

  if (group->n_mem != n_mem)
    goto n_mem_missmatch;

  for (i = 0; i < group->n_mem; i++)
  {
    gint dmafd;
    gsize size, offset, maxsize;

    if (!gst_is_dmabuf_memory (dma_mem[i]))
      goto not_dmabuf;

    size = gst_memory_get_sizes (dma_mem[i], &offset, &maxsize);

    dmafd = gst_dmabuf_memory_get_fd (dma_mem[i]);

    GST_LOG_OBJECT (allocator, "[%i] imported DMABUF as fd %i plane %d",
        group->buffer.index, dmafd, i);

    mem = (GstAmlV4l2Memory *) group->mem[i];

    /* Update memory */
    mem->mem.maxsize = maxsize;
    mem->mem.offset = offset;
    mem->mem.size = size;
    mem->dmafd = dmafd;

    /* Update v4l2 structure */
    group->planes[i].length = maxsize;
    group->planes[i].bytesused = size + offset;
    group->planes[i].m.fd = dmafd;
    group->planes[i].data_offset = offset;
  }

  /* Copy into buffer structure if not using planes */
  if (!V4L2_TYPE_IS_MULTIPLANAR(obj->type))
  {
    group->buffer.bytesused = group->planes[0].bytesused;
    group->buffer.length = group->planes[0].length;
    group->buffer.m.fd = group->planes[0].m.fd;

    /* FIXME Check if data_offset > 0 and fail for non-multi-planar */
    g_assert (group->planes[0].data_offset == 0);
  }
  else
  {
    group->buffer.length = group->n_mem;
  }

  return TRUE;

n_mem_missmatch:
  {
    GST_ERROR_OBJECT (allocator, "Got %i dmabuf but needed %i", n_mem,
        group->n_mem);
    return FALSE;
  }
not_dmabuf:
  {
    GST_ERROR_OBJECT (allocator, "Memory %i is not of DMABUF", i);
    return FALSE;
  }
}

gboolean
gst_aml_v4l2_allocator_import_userptr(GstAmlV4l2Allocator *allocator,
    GstAmlV4l2MemoryGroup *group, gsize img_size, int n_planes,
    gpointer * data, gsize * size)
{
  GstAmlV4l2Object *obj = allocator->obj;
  GstAmlV4l2Memory *mem;
  gint i;

  g_return_val_if_fail (allocator->memory == V4L2_MEMORY_USERPTR, FALSE);

  /* TODO Support passing N plane from 1 memory to MPLANE v4l2 format */
  if (V4L2_TYPE_IS_MULTIPLANAR (obj->type) && n_planes != group->n_mem)
    goto n_mem_missmatch;

  for (i = 0; i < group->n_mem; i++)
  {
    gsize maxsize, psize;

    /* TODO request used size and maxsize separately */
    if (V4L2_TYPE_IS_MULTIPLANAR (obj->type))
      maxsize = psize = size[i];
    else
      maxsize = psize = img_size;

    g_assert (psize <= img_size);

    GST_LOG_OBJECT(allocator, "[%i] imported USERPTR %p plane %d size %" G_GSIZE_FORMAT, group->buffer.index, data[i], i, psize);

    mem = (GstAmlV4l2Memory *)group->mem[i];

    mem->mem.maxsize = maxsize;
    mem->mem.size = psize;
    mem->data = data[i];

    group->planes[i].length = maxsize;
    group->planes[i].bytesused = psize;
    group->planes[i].m.userptr = (unsigned long) data[i];
    group->planes[i].data_offset = 0;
  }

  /* Copy into buffer structure if not using planes */
  if (!V4L2_TYPE_IS_MULTIPLANAR(obj->type))
  {
    group->buffer.bytesused = group->planes[0].bytesused;
    group->buffer.length = group->planes[0].length;
    group->buffer.m.userptr = group->planes[0].m.userptr;
  }
  else
  {
    group->buffer.length = group->n_mem;
  }

  return TRUE;

n_mem_missmatch:
  {
    GST_ERROR_OBJECT (allocator, "Got %i userptr plane while driver need %i",
        n_planes, group->n_mem);
    return FALSE;
  }
}

void gst_aml_v4l2_allocator_flush(GstAmlV4l2Allocator *allocator)
{
  gint i;

  GST_OBJECT_LOCK (allocator);

  if (!g_atomic_int_get (&allocator->active))
    goto done;

  for (i = 0; i < allocator->count; i++)
  {
    GstAmlV4l2MemoryGroup *group = allocator->groups[i];
    gint n;

    if (IS_QUEUED (group->buffer))
    {
      UNSET_QUEUED (group->buffer);

      gst_aml_v4l2_allocator_reset_group (allocator, group);

      for (n = 0; n < group->n_mem; n++)
        gst_memory_unref (group->mem[n]);
    }
  }

done:
  GST_OBJECT_UNLOCK (allocator);
}

gboolean
gst_aml_v4l2_allocator_qbuf(GstAmlV4l2Allocator *allocator,
                            GstAmlV4l2MemoryGroup *group)
{
  GstAmlV4l2Object *obj = allocator->obj;
  gboolean ret = TRUE;
  gint i;

  g_return_val_if_fail (g_atomic_int_get (&allocator->active), FALSE);

  /* update sizes */
  if (V4L2_TYPE_IS_MULTIPLANAR (obj->type))
  {
    for (i = 0; i < group->n_mem; i++)
      group->planes[i].bytesused =
          gst_memory_get_sizes (group->mem[i], NULL, NULL);
  }
  else
  {
    group->buffer.bytesused = gst_memory_get_sizes (group->mem[0], NULL, NULL);
  }

  /* Ensure the memory will stay around and is RO */
  for (i = 0; i < group->n_mem; i++)
    gst_memory_ref (group->mem[i]);

  gint64 currFramePTS= 0;
  if (group->buffer.timestamp.tv_sec != -1) {
    currFramePTS= group->buffer.timestamp.tv_sec * 1000000LL + group->buffer.timestamp.tv_usec;
  }
  GST_LOG_OBJECT(allocator, "q buffer, timestamp:%lld",currFramePTS);

  gst_aml_v4l2_allocator_dump_es_buf(allocator, group);

  if (obj->ioctl(obj->video_fd, VIDIOC_QBUF, &group->buffer) < 0)
  {
    GST_ERROR_OBJECT (allocator, "failed queueing buffer %i: %s",
        group->buffer.index, g_strerror (errno));

    /* Release the memory, possibly making it RW again */
    for (i = 0; i < group->n_mem; i++)
      gst_memory_unref (group->mem[i]);

    ret = FALSE;
    if (IS_QUEUED(group->buffer))
    {
      GST_DEBUG_OBJECT (allocator,
          "driver pretends buffer is queued even if queue failed");
      UNSET_QUEUED (group->buffer);
    }
    goto done;
  }

  GST_LOG_OBJECT (allocator, "queued buffer %i (flags 0x%X)",
      group->buffer.index, group->buffer.flags);

  if (!IS_QUEUED(group->buffer))
  {
    GST_DEBUG_OBJECT (allocator,
        "driver pretends buffer is not queued even if queue succeeded");
    SET_QUEUED (group->buffer);
  }

done:
  return ret;
}

GstFlowReturn
gst_aml_v4l2_allocator_dqbuf(GstAmlV4l2Allocator *allocator,
                             GstAmlV4l2MemoryGroup **group_out)
{
  GstAmlV4l2Object *obj = allocator->obj;
  struct v4l2_buffer buffer = { 0 };
  struct v4l2_plane planes[VIDEO_MAX_PLANES] = { {0} };
  gint i;

  GstAmlV4l2MemoryGroup *group = NULL;

  g_return_val_if_fail (g_atomic_int_get (&allocator->active), GST_FLOW_ERROR);

  buffer.type = obj->type;
  buffer.memory = allocator->memory;

  if (V4L2_TYPE_IS_MULTIPLANAR (obj->type))
  {
    buffer.length = obj->format.fmt.pix_mp.num_planes;
    buffer.m.planes = planes;
  }

  if (obj->ioctl (obj->video_fd, VIDIOC_DQBUF, &buffer) < 0)
    goto error;

  group = allocator->groups[buffer.index];

  if (!IS_QUEUED(group->buffer))
  {
    GST_ERROR_OBJECT (allocator,
        "buffer %i was not queued, this indicate a driver bug.", buffer.index);
    return GST_FLOW_ERROR;
  }

  group->buffer = buffer;

  GST_LOG_OBJECT (allocator, "dequeued buffer %i (flags 0x%X)", buffer.index,
      buffer.flags);

  if (IS_QUEUED(group->buffer))
  {
    GST_DEBUG_OBJECT (allocator,
        "driver pretends buffer is queued even if dequeue succeeded");
    UNSET_QUEUED (group->buffer);
  }

  if (V4L2_TYPE_IS_MULTIPLANAR(obj->type))
  {
    group->buffer.m.planes = group->planes;
    memcpy (group->planes, buffer.m.planes, sizeof (planes));
  }
  else
  {
    group->planes[0].bytesused = group->buffer.bytesused;
    group->planes[0].length = group->buffer.length;
    g_assert (sizeof (group->planes[0].m) == sizeof (group->buffer.m));
    memcpy (&group->planes[0].m, &group->buffer.m, sizeof (group->buffer.m));
  }

  /* And update memory size */
  if (V4L2_TYPE_IS_OUTPUT(obj->type))
  {
    gst_aml_v4l2_allocator_reset_size(allocator, group);
  }
  else
  {
    /* for capture, simply read the size */
    for (i = 0; i < group->n_mem; i++)
    {
      gsize size, offset;

      GST_LOG_OBJECT (allocator,
          "Dequeued capture buffer, length: %u bytesused: %u data_offset: %u",
          group->planes[i].length, group->planes[i].bytesused,
          group->planes[i].data_offset);

      offset = group->planes[i].data_offset;

      if (group->planes[i].bytesused > group->planes[i].data_offset)
      {
        size = group->planes[i].bytesused - group->planes[i].data_offset;
      }
      else
      {
        GST_WARNING_OBJECT(allocator, "V4L2 provided buffer has bytesused %" G_GUINT32_FORMAT " which is too small to include data_offset %" G_GUINT32_FORMAT, group->planes[i].bytesused,
                           group->planes[i].data_offset);
        size = group->planes[i].bytesused;
        /*if this buffer is last buffer,bytesused is 0,so size equal 0,this cause assert fail of gst_memory_resize*/
        if ( (group->buffer.flags & V4L2_BUF_FLAG_LAST) &&(group->buffer.bytesused == 0))
        {
          size = group->planes[i].length;
        }
      }

      if (G_LIKELY (size + offset <= group->mem[i]->maxsize))
        gst_memory_resize (group->mem[i], offset, size);
      else
      {
        GST_WARNING_OBJECT (allocator,
            "v4l2 provided buffer that is too big for the memory it was "
            "writing into.  v4l2 claims %" G_GSIZE_FORMAT " bytes used but "
            "memory is only %" G_GSIZE_FORMAT "B.  This is probably a driver "
            "bug.", size, group->mem[i]->maxsize);
        gst_memory_resize (group->mem[i], 0, group->mem[i]->maxsize);
      }
    }
  }

  /* Release the memory, possibly making it RW again */
  for (i = 0; i < group->n_mem; i++)
    gst_memory_unref (group->mem[i]);

  *group_out = group;
  return GST_FLOW_OK;

error:
  if (errno == EPIPE)
  {
    GST_DEBUG_OBJECT (allocator, "broken pipe signals last buffer");
    return GST_FLOW_EOS;
  }

  GST_ERROR_OBJECT (allocator, "failed dequeuing a %s buffer: %s",
      memory_type_to_str (allocator->memory), g_strerror (errno));

  switch (errno)
  {
    case EAGAIN:
      GST_WARNING_OBJECT (allocator,
          "Non-blocking I/O has been selected using O_NONBLOCK and"
          " no buffer was in the outgoing queue.");
      break;
    case EINVAL:
      GST_ERROR_OBJECT (allocator,
          "The buffer type is not supported, or the index is out of bounds, "
          "or no buffers have been allocated yet, or the userptr "
          "or length are invalid.");
      break;
    case ENOMEM:
      GST_ERROR_OBJECT (allocator,
          "insufficient memory to enqueue a user pointer buffer");
      break;
    case EIO:
      GST_INFO_OBJECT (allocator,
          "VIDIOC_DQBUF failed due to an internal error."
          " Can also indicate temporary problems like signal loss."
          " Note the driver might dequeue an (empty) buffer despite"
          " returning an error, or even stop capturing.");
      /* have we de-queued a buffer ? */
      if (!IS_QUEUED(buffer))
      {
        GST_DEBUG_OBJECT (allocator, "reenqueueing buffer");
        /* FIXME ... should we do something here? */
      }
      break;
    case EINTR:
      GST_WARNING_OBJECT (allocator, "could not sync on a buffer on device");
      break;
    default:
      GST_WARNING_OBJECT (allocator,
          "Grabbing frame got interrupted unexpectedly. %d: %s.", errno,
          g_strerror (errno));
      break;
  }

  return GST_FLOW_ERROR;
}

void
gst_aml_v4l2_allocator_reset_group (GstAmlV4l2Allocator *allocator,
    GstAmlV4l2MemoryGroup *group)
{
  switch (allocator->memory)
  {
    case V4L2_MEMORY_USERPTR:
      gst_aml_v4l2_allocator_clear_userptr (allocator, group);
      break;
    case V4L2_MEMORY_DMABUF:
      gst_aml_v4l2_allocator_clear_dmabufin (allocator, group);
      break;
    case V4L2_MEMORY_MMAP:
      break;
    default:
      g_assert_not_reached ();
      break;
  }

  gst_aml_v4l2_allocator_reset_size(allocator, group);
}