media: v4l2-mem2mem: support held capture buffers

Check for held buffers that are ready to be returned to vb2 in
__v4l2_m2m_try_queue(). This avoids drivers having to handle this
case.

Add v4l2_m2m_buf_done_and_job_finish() to correctly return source
and destination buffers and mark the job as finished while taking
a held destination buffer into account (i.e. that buffer won't be
returned). This has to be done while job_spinlock is held to avoid
race conditions.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

1 files changed, 31 insertions, 2 deletions

diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 0b9c3a287061..229d9f5d4370 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -21,7 +21,8 @@
  *		callback.
  *		The job does NOT have to end before this callback returns
  *		(and it will be the usual case). When the job finishes,
- *		v4l2_m2m_job_finish() has to be called.
+ *		v4l2_m2m_job_finish() or v4l2_m2m_buf_done_and_job_finish()
+ *		has to be called.
  * @job_ready:	optional. Should return 0 if the driver does not have a job
  *		fully prepared to run yet (i.e. it will not be able to finish a
  *		transaction without sleeping). If not provided, it will be
@@ -33,7 +34,8 @@
  *		stop the device safely; e.g. in the next interrupt handler),
  *		even if the transaction would not have been finished by then.
  *		After the driver performs the necessary steps, it has to call
- *		v4l2_m2m_job_finish() (as if the transaction ended normally).
+ *		v4l2_m2m_job_finish() or v4l2_m2m_buf_done_and_job_finish() as
+ *		if the transaction ended normally.
  *		This function does not have to (and will usually not) wait
  *		until the device enters a state when it can be stopped.
  */
@@ -173,6 +175,33 @@ void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx);
 void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
 			 struct v4l2_m2m_ctx *m2m_ctx);
 
+/**
+ * v4l2_m2m_buf_done_and_job_finish() - return source/destination buffers with
+ * state and inform the framework that a job has been finished and have it
+ * clean up
+ *
+ * @m2m_dev: opaque pointer to the internal data to handle M2M context
+ * @m2m_ctx: m2m context assigned to the instance given by struct &v4l2_m2m_ctx
+ * @state: vb2 buffer state passed to v4l2_m2m_buf_done().
+ *
+ * Drivers that set V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF must use this
+ * function instead of job_finish() to take held buffers into account. It is
+ * optional for other drivers.
+ *
+ * This function removes the source buffer from the ready list and returns
+ * it with the given state. The same is done for the destination buffer, unless
+ * it is marked 'held'. In that case the buffer is kept on the ready list.
+ *
+ * After that the job is finished (see job_finish()).
+ *
+ * This allows for multiple output buffers to be used to fill in a single
+ * capture buffer. This is typically used by stateless decoders where
+ * multiple e.g. H.264 slices contribute to a single decoded frame.
+ */
+void v4l2_m2m_buf_done_and_job_finish(struct v4l2_m2m_dev *m2m_dev,
+				      struct v4l2_m2m_ctx *m2m_ctx,
+				      enum vb2_buffer_state state);
+
 static inline void
 v4l2_m2m_buf_done(struct vb2_v4l2_buffer *buf, enum vb2_buffer_state state)
 {