Re: [RFC PATCH 3/5] media: iris: Signal V4L2_EVENT_EOS only at the end of a drain

[Bryan O'Donoghue <bod@kernel.org>]

On 27/10/2026 03:19, Christian Cortner wrote:
> iris_vb2_buffer_done() and iris_vb2_buf_queue() queue V4L2_EVENT_EOS and
> mark the m2m context as stopped for every capture buffer flagged
> V4L2_BUF_FLAG_LAST, including the one that ends a dynamic resolution
> change. In the stateful decoder interface the (deprecated) EOS event is
> part of the drain sequence only, and a resolution change is not the end
> of the stream: a client that still acts on the event, like ffmpeg's
> h264_v4l2m2m decoder, stops decoding at the first resolution change in
> the stream. And since nothing in the driver clears the stopped mark
> again, the EOS event of the drain at the real end of such a stream is
> never sent.

More word salad. I'd almost drop that entire paragraph - hitting you 
with these stuttering paragraphs is !elucidating - kind of the opposite.

> Queue the event, and mark the context as stopped, only when the LAST
> buffer ends a drain, that is when IRIS_INST_SUB_DRAIN_LAST is set. Both
> HFI generations set it before they return the LAST buffer of a drain,
> for the decoder and the encoder alike.

This is much clearer.
> Fixes: 84e17adae3e3 ("media: iris: add support for dynamic resolution change")
> Cc: stable@vger.kernel.org
> Assisted-by: LLM sparse smatch
> ---
> Reference only, not for merging (no Signed-off-by); see the cover
> letter.
> 
>   drivers/media/platform/qcom/iris/iris_buffer.c | 7 ++++++-
>   drivers/media/platform/qcom/iris/iris_vb2.c    | 4 +++-
>   2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/qcom/iris/iris_buffer.c b/drivers/media/platform/qcom/iris/iris_buffer.c
> index eb8de60c1177..ff2a1b331ac2 100644
> --- a/drivers/media/platform/qcom/iris/iris_buffer.c
> +++ b/drivers/media/platform/qcom/iris/iris_buffer.c
> @@ -913,7 +913,12 @@ int iris_vb2_buffer_done(struct iris_inst *inst, struct iris_buffer *buf)
>   	}
> 
>   	if (vbuf->flags & V4L2_BUF_FLAG_LAST) {
> -		if (!v4l2_m2m_has_stopped(m2m_ctx)) {
> +		/*
> +		 * Only a drain ends with V4L2_EVENT_EOS: the LAST buffer of a
> +		 * source change is not the end of the stream.
> +		 */
> +		if (inst->sub_state & IRIS_INST_SUB_DRAIN_LAST &&
> +		    !v4l2_m2m_has_stopped(m2m_ctx)) {
>   			const struct v4l2_event ev = { .type = V4L2_EVENT_EOS };
> 
>   			v4l2_event_queue_fh(&inst->fh, &ev);
> diff --git a/drivers/media/platform/qcom/iris/iris_vb2.c b/drivers/media/platform/qcom/iris/iris_vb2.c
> index 8faf709c26c1..b820b3e43910 100644
> --- a/drivers/media/platform/qcom/iris/iris_vb2.c
> +++ b/drivers/media/platform/qcom/iris/iris_vb2.c
> @@ -324,7 +324,9 @@ void iris_vb2_buf_queue(struct vb2_buffer *vb2)
>   			vbuf->field = V4L2_FIELD_NONE;
>   			vb2_set_plane_payload(vb2, 0, 0);
>   			v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_DONE);
> -			if (!v4l2_m2m_has_stopped(m2m_ctx)) {
> +			/* EOS ends a drain only, see iris_vb2_buffer_done() */
> +			if (inst->sub_state & IRIS_INST_SUB_DRAIN_LAST &&
> +			    !v4l2_m2m_has_stopped(m2m_ctx)) {

Adding the flag over and over again is pretty mindless.

Add a function or wrapper to capture this logic - we had functional 
decomposition in the previous patch - but distinctly lacking here.

=>

$ grep -r v4l2_m2m_has_stopped drivers/media/platform/qcom/iris/*
drivers/media/platform/qcom/iris/iris_buffer.c:		if 
(!v4l2_m2m_has_stopped(m2m_ctx)) {
drivers/media/platform/qcom/iris/iris_vb2.c:			if 
(!v4l2_m2m_has_stopped(m2m_ctx)) {


>   				v4l2_event_queue_fh(&inst->fh, &eos);
>   				v4l2_m2m_mark_stopped(m2m_ctx);
>   			}
> --
> 2.56.0
>