[media] vb2: retry start_streaming in case of insufficient buffers

[platform/adaptation/renesas_rcar/renesas_kernel.git] / include / media / videobuf2-core.h

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index ea76652..bef53ce 100644 (file)
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -252,10 +252,13 @@ struct vb2_buffer {
  *                     receive buffers with @buf_queue callback before
  *                     @start_streaming is called; the driver gets the number
  *                     of already queued buffers in count parameter; driver
- *                     can return an error if hardware fails or not enough
- *                     buffers has been queued, in such case all buffers that
- *                     have been already given by the @buf_queue callback are
- *                     invalidated.
+ *                     can return an error if hardware fails, in that case all
+ *                     buffers that have been already given by the @buf_queue
+ *                     callback are invalidated.
+ *                     If there were not enough queued buffers to start
+ *                     streaming, then this callback returns -ENOBUFS, and the
+ *                     vb2 core will retry calling @start_streaming when a new
+ *                     buffer is queued.
  * @stop_streaming:    called when 'streaming' state must be disabled; driver
  *                     should stop any DMA transactions or wait until they
  *                     finish and give back all buffers it got from buf_queue()
@@ -323,6 +326,9 @@ struct v4l2_fh;
  * @done_wq:   waitqueue for processes waiting for buffers ready to be dequeued
  * @alloc_ctx: memory type/allocator-specific contexts for each plane
  * @streaming: current streaming state
+ * @retry_start_streaming: start_streaming() was called, but there were not enough
+ *             buffers queued. If set, then retry calling start_streaming when
+ *             queuing a new buffer.
  * @fileio:    file io emulator internal data, used only if emulator is active
  */
 struct vb2_queue {
@@ -355,6 +361,7 @@ struct vb2_queue {
        unsigned int                    plane_sizes[VIDEO_MAX_PLANES];
 
        unsigned int                    streaming:1;
+       unsigned int                    retry_start_streaming:1;
 
        struct vb2_fileio_data          *fileio;
 };