linux-kernel - Re: [PATCH] media: iris: remove v4l2_m2m_ioctl_{de,en}coder

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Message-ID: <ca6313d1-b5c8-466d-8ed1-ab9ac6d8a803@oss.qualcomm.com>
Date: Wed, 5 Nov 2025 17:26:08 +0530
From: Vikash Garodia <vikash.garodia@....qualcomm.com>
To: Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Bryan O'Donoghue <bod@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...nel.org>,
        Stefan Schmidt <stefan.schmidt@...aro.org>
Cc: linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: iris: remove v4l2_m2m_ioctl_{de,en}coder_cmd API
 usage during STOP handling

On 11/2/2025 9:10 AM, Dikshita Agarwal wrote:
> Currently v4l2_m2m_ioctl_{de,enc}coder_cmd is being invoked during STOP
> command handling. However, this is not required as the iris driver has
> its own drain and stop handling mechanism in place.
>
> Using the m2m command API in this context leads to incorrect behavior,
> where the LAST flag is prematurely attached to a capture buffer,
> when there are no buffers in m2m source queue. But, in this scenario
> even though the source buffers are returned to client, hardware might
> still need to process the pending capture buffers.
>
> Attaching LAST flag prematurely can result in the capture buffer being
> removed from the destination queue before the hardware has finished
> processing it, causing issues when the buffer is eventually returned by
> the hardware.
>
> To prevent this, remove the m2m API usage in stop handling.
>
> Fixes: d09100763bed ("media: iris: add support for drain sequence")
> Fixes: 75db90ae067d ("media: iris: Add support for drain sequence in encoder video device")
> Signed-off-by: Dikshita Agarwal<dikshita.agarwal@....qualcomm.com>

Reviewed-by: Vikash Garodia<vikash.garodia@....qualcomm.com>