linux-kernel - Re: [PATCH v21 3/9] media: test-drivers: Set REQBUFS minimum number of buffers

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Message-ID: <00fe576e-df97-4cae-9937-d8e9272cf5e0@xs4all.nl>
Date: Mon, 18 Mar 2024 14:06:33 +0100
From: Hans Verkuil <hverkuil-cisco@...all.nl>
To: Benjamin Gaignard <benjamin.gaignard@...labora.com>, mchehab@...nel.org,
 tfiga@...omium.org, m.szyprowski@...sung.com, ezequiel@...guardiasur.com.ar,
 p.zabel@...gutronix.de, nicolas@...fresne.ca
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-rockchip@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH v21 3/9] media: test-drivers: Set REQBUFS minimum number
 of buffers

On 18/03/2024 11:06 am, Hans Verkuil wrote:
> Hi Benjamin,
> 
> On 14/03/2024 4:32 pm, Benjamin Gaignard wrote:
>> Instead of using 'min_queued_buffers' field to specify the
>> minimum number of buffers to be allocated when calling REQBUF
>> use 'min_reqbufs_allocation' field which is dedicated to this
>> purpose.
>>
>> While at it rename vivid_create_queue() parameter.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...labora.com>
>> ---
>>  drivers/media/test-drivers/vimc/vimc-capture.c | 2 +-
>>  drivers/media/test-drivers/vivid/vivid-core.c  | 4 ++--
>>  2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/test-drivers/vimc/vimc-capture.c b/drivers/media/test-drivers/vimc/vimc-capture.c
>> index 2a2d19d23bab..97693561f1e4 100644
>> --- a/drivers/media/test-drivers/vimc/vimc-capture.c
>> +++ b/drivers/media/test-drivers/vimc/vimc-capture.c
>> @@ -432,7 +432,7 @@ static struct vimc_ent_device *vimc_capture_add(struct vimc_device *vimc,
>>  	q->mem_ops = vimc_allocator == VIMC_ALLOCATOR_DMA_CONTIG
>>  		   ? &vb2_dma_contig_memops : &vb2_vmalloc_memops;
>>  	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>> -	q->min_queued_buffers = 2;
>> +	q->min_reqbufs_allocation = 2;
>>  	q->lock = &vcapture->lock;
>>  	q->dev = v4l2_dev->dev;
>>  
>> diff --git a/drivers/media/test-drivers/vivid/vivid-core.c b/drivers/media/test-drivers/vivid/vivid-core.c
>> index 159c72cbb5bf..11b8520d9f57 100644
>> --- a/drivers/media/test-drivers/vivid/vivid-core.c
>> +++ b/drivers/media/test-drivers/vivid/vivid-core.c
>> @@ -861,7 +861,7 @@ static const struct media_device_ops vivid_media_ops = {
>>  static int vivid_create_queue(struct vivid_dev *dev,
>>  			      struct vb2_queue *q,
>>  			      u32 buf_type,
>> -			      unsigned int min_queued_buffers,
>> +			      unsigned int min_reqbufs_allocation,
>>  			      const struct vb2_ops *ops)
>>  {
>>  	if (buf_type == V4L2_BUF_TYPE_VIDEO_CAPTURE && dev->multiplanar)
>> @@ -898,7 +898,7 @@ static int vivid_create_queue(struct vivid_dev *dev,
>>  	q->mem_ops = allocators[dev->inst] == 1 ? &vb2_dma_contig_memops :
>>  						  &vb2_vmalloc_memops;
>>  	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>> -	q->min_queued_buffers = supports_requests[dev->inst] ? 0 : min_queued_buffers;
>> +	q->min_reqbufs_allocation = min_reqbufs_allocation;
>>  	q->lock = &dev->mutex;
>>  	q->dev = dev->v4l2_dev.dev;
>>  	q->supports_requests = supports_requests[dev->inst];
> 
> How did you test this series? If I run the test-media script using the patch
> v4l2-compliance (the v9 series) I get two failures. Both are traced to code
> in vivid: meta_out_queue_setup() and touch_cap_queue_setup():
> 
> Both have this code:
> 
>         if (*nplanes) {
>                 if (sizes[0] < size)
>                         return -EINVAL;
>         } else {
>                 sizes[0] = size;
>         }
> 
>         if (q_num_bufs + *nbuffers < 2)
>                 *nbuffers = 2 - q_num_bufs;
> 
>         *nplanes = 1;
>         return 0;
> 
> It's the *nbuffers assignment that is wrong. Looking at vivid-core.c I see
> that vivid_create_queue() is called with min_reqbufs_allocation set to 1 for
> these two devices. I think that should be 2, and then the code above can
> be dropped.

Note that if that 'if (q_num_bufs + *nbuffers < 2)' is dropped, then you
should also drop the q_num_bufs assignment at the beginning of the function
since that is now no longer used.

Regards,

	Hans

> 
> It is probably best to post a v21.1 3/9 patch only.
> 
> Regards,
> 
> 	Hans
> 
> 
>