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Message-ID: <5dfeaf67-b6c6-45be-bc28-04751376ea26@xs4all.nl>
Date:   Mon, 4 Dec 2023 16:07:37 +0100
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Subject: Re: [PATCH v2 31/36] media: starfive: Fix misuse of
 min_buffers_needed field
Content-Language: en-US, nl
To:     Benjamin Gaignard <benjamin.gaignard@collabora.com>,
        mchehab@kernel.org, tfiga@chromium.org, m.szyprowski@samsung.com,
        matt.ranostay@konsulko.com
Cc:     linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        linux-staging@lists.linux.dev, kernel@collabora.com,
        Jack Zhu <jack.zhu@starfivetech.com>,
        Changhuang Liang <changhuang.liang@starfivetech.com>
References: <20231204132323.22811-1-benjamin.gaignard@collabora.com>
 <20231204132323.22811-32-benjamin.gaignard@collabora.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
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In-Reply-To: <20231204132323.22811-32-benjamin.gaignard@collabora.com>
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Precedence: bulk

On 04/12/2023 14:23, Benjamin Gaignard wrote:
> 'min_buffers_needed' is suppose to be used to indicate the number
> of buffers needed by DMA engine to start streaming.
> starfive driver doesn't use DMA engine and just want to specify
> the minimum number of buffers to allocate when calling VIDIOC_REQBUFS.
> That 'min_reqbufs_allocation' field purpose so use it.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> CC: Jack Zhu <jack.zhu@starfivetech.com>
> CC: Changhuang Liang <changhuang.liang@starfivetech.com>
> ---
>  drivers/staging/media/starfive/camss/stf-video.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/media/starfive/camss/stf-video.c b/drivers/staging/media/starfive/camss/stf-video.c
> index 0b305f21eb53..25038e37e8a6 100644
> --- a/drivers/staging/media/starfive/camss/stf-video.c
> +++ b/drivers/staging/media/starfive/camss/stf-video.c
> @@ -513,7 +513,7 @@ int stf_video_register(struct stfcamss_video *video,
>  	q->buf_struct_size = sizeof(struct stfcamss_buffer);
>  	q->dev = video->stfcamss->dev;
>  	q->lock = &video->q_lock;
> -	q->min_buffers_needed = STFCAMSS_MIN_BUFFERS;
> +	q->min_reqbufs_allocation = STFCAMSS_MIN_BUFFERS;
>  	ret = vb2_queue_init(q);
>  	if (ret < 0) {
>  		dev_err(video->stfcamss->dev,

It's not clear to me if this driver can work without at least one buffer
queued. This would need to be tested first.

Regards,

	Hans