linux-kernel - Re: [PATCH] media: venus: vdec: fix error state assignment for zero bytesused

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Message-ID: <32bf8a1a-9e9b-438c-89c7-9fa0c88e9ca2@oss.qualcomm.com>
Date: Mon, 8 Dec 2025 10:29:41 +0800
From: Renjiang Han <renjiang.han@....qualcomm.com>
To: Bryan O'Donoghue <bod@...nel.org>,
        Vikash Garodia <vikash.garodia@....qualcomm.com>,
        Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: venus: vdec: fix error state assignment for zero
 bytesused


On 12/7/2025 7:56 AM, Bryan O'Donoghue wrote:
> On 26/11/2025 04:23, Renjiang Han wrote:
>> Previously, the check for zero bytesused and the assignment of error
>> state was performed outside the V4L2_BUF_FLAG_LAST branch, which could
>> incorrectly set the error state during drain operations. 
>
> This deserves more elaboration.
>
> Instead of saying previously - talk about what it currently does and 
> the precise circumstances under which it goes wrong. Try to make the 
> description as plain and concise as possible.
>
> This patch
>> moves the zero-bytesused check inside the 'else' branch, ensuring that
>> the error state is only set for non-EOS buffers with zero payload.
>>
>> Additionally, the patch keeps the rest of the buffer state handling
>> logic unchanged, including handling of HFI_BUFFERFLAG_DATACORRUPT and
>> HFI_BUFFERFLAG_DROP_FRAME.
>
> I don't think you need to tell us what's not touched in your commit log.
>
> - Tell us what is wrong directly and plainly.
>   Include how the bug you are fixing can come about i.e. under what
>   circumstances we would see the error.
>
> - Then tell us how you've fixed it.
>
> - And include a Fixes: tag please.
>   Since this is a bug fix you are proposing, it needs to be backported.
sure, thanks for your comments.
>
>>
>> Signed-off-by: Renjiang Han <renjiang.han@....qualcomm.com>
>> ---
>> This patch refines the error state assignment logic in the Venus vdec
>> driver for Qualcomm platforms. Specifically, it ensures that the buffer
>> state is only set to VB2_BUF_STATE_ERROR for non-EOS capture buffers
>> with zero bytesused, preventing false error reporting during drain
>> operations.
>> ---
>>   drivers/media/platform/qcom/venus/vdec.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/platform/qcom/venus/vdec.c 
>> b/drivers/media/platform/qcom/venus/vdec.c
>> index 
>> 4a6641fdffcf79705893be58c7ec5cf485e2fab9..d0bd2d86a31f9a18cb68b08ba66affdf8fc5092d 
>> 100644
>> --- a/drivers/media/platform/qcom/venus/vdec.c
>> +++ b/drivers/media/platform/qcom/venus/vdec.c
>> @@ -1440,10 +1440,10 @@ static void vdec_buf_done(struct venus_inst 
>> *inst, unsigned int buf_type,
>>                   inst->drain_active = false;
>>                   inst->codec_state = VENUS_DEC_STATE_STOPPED;
>>               }
>> +        } else {
>> +            if (!bytesused)
>> +                state = VB2_BUF_STATE_ERROR;
>>           }
>> -
>> -        if (!bytesused)
>> -            state = VB2_BUF_STATE_ERROR;
>>       } else {
>>           vbuf->sequence = inst->sequence_out++;
>>       }
>>
>> ---
>> base-commit: 663d0d1af3faefe673cabf4b6b077149a87ad71f
>> change-id: 20251126-fix-error-state-24183a8538cd
>>
>> Best regards,
>> -- 
>> Renjiang Han <renjiang.han@....qualcomm.com>
>>
>
-- 
Best regards,
Renjiang Han