Re: [PATCH 27/55] media: sun6i-isp: Stop abusing of min_buffers_needed field

[Benjamin Gaignard]

Le 29/11/2023 à 14:40, Paul Kocialkowski a écrit :
> Hi Benjamin,
>
> On Mon 27 Nov 23, 17:54, Benjamin Gaignard wrote:
> > 'min_buffers_needed' is suppose to be used to indicate the number
> > of buffers needed by DMA engine to start streaming.
> > sun6i-isp 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.
> The hardware actually has its own DMA engine. It can work with just one buffer
> though (which will never be returned to userspace). But I think we should still
> require at least two buffers allocated, otherwise the driver will be of no use
> at all.
>
> So I don't think the commit message here is correct.

That is exactly the info I hope to get for this first series since I don't know
each hardware block details.
I will remove this commit and make the driver use min_queued_buffers field instead
so that will fit with it needs.

Thanks,
Benjamin

> Cheers,
>
> Paul
>
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > CC: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
> > CC: Chen-Yu Tsai <wens@xxxxxxxx>
> > CC: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> > CC: Samuel Holland <samuel@xxxxxxxxxxxx>
> > CC: linux-sunxi@xxxxxxxxxxxxxxx
> > ---
> >   drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_capture.c | 2 +-
> >   drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_params.c  | 2 +-
> >   2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_capture.c b/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_capture.c
> > index 1595a9607775..f47f9946c19f 100644
> > --- a/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_capture.c
> > +++ b/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_capture.c
> > @@ -660,7 +660,7 @@ int sun6i_isp_capture_setup(struct sun6i_isp_device *isp_dev)
> >   	queue->buf_struct_size = sizeof(struct sun6i_isp_buffer);
> >   	queue->ops = &sun6i_isp_capture_queue_ops;
> >   	queue->mem_ops = &vb2_dma_contig_memops;
> > -	queue->min_buffers_needed = 2;
> > +	queue->min_reqbufs_allocation = 2;
> >   	queue->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> >   	queue->lock = &capture->lock;
> >   	queue->dev = isp_dev->dev;
> > diff --git a/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_params.c b/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_params.c
> > index e28be895b486..259f6bfcb620 100644
> > --- a/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_params.c
> > +++ b/drivers/staging/media/sunxi/sun6i-isp/sun6i_isp_params.c
> > @@ -489,7 +489,7 @@ int sun6i_isp_params_setup(struct sun6i_isp_device *isp_dev)
> >   	queue->buf_struct_size = sizeof(struct sun6i_isp_buffer);
> >   	queue->ops = &sun6i_isp_params_queue_ops;
> >   	queue->mem_ops = &vb2_vmalloc_memops;
> > -	queue->min_buffers_needed = 1;
> > +	queue->min_reqbufs_allocation = 1;
> >   	queue->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> >   	queue->lock = &params->lock;
> >   	queue->dev = isp_dev->dev;
> > --
> > 2.39.2