2022-03-22 08:53:44

by Ming Qian

Subject: [PATCH] media: amphion: ensure the buffer count is not less than min_buffer

the output buffer count should >= min_buffer_out
the capture buffer count should >= min_buffer_cap

Signed-off-by: Ming Qian <[email protected]>
---
drivers/media/platform/amphion/vpu_v4l2.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/media/platform/amphion/vpu_v4l2.c b/drivers/media/platform/amphion/vpu_v4l2.c
index cbf3315605a9..72a0544f4da3 100644
--- a/drivers/media/platform/amphion/vpu_v4l2.c
+++ b/drivers/media/platform/amphion/vpu_v4l2.c
@@ -355,6 +355,10 @@ static int vpu_vb2_queue_setup(struct vb2_queue *vq,
return 0;
}

+ if (V4L2_TYPE_IS_OUTPUT(vq->type))
+ *buf_count = max_t(unsigned int, *buf_count, inst->min_buffer_out);
+ else
+ *buf_count = max_t(unsigned int, *buf_count, inst->min_buffer_cap);
*plane_count = cur_fmt->num_planes;
for (i = 0; i < cur_fmt->num_planes; i++)
psize[i] = cur_fmt->sizeimage[i];
--
2.33.0

2022-04-27 11:17:14

by Hans Verkuil

Subject: Re: [PATCH] media: amphion: ensure the buffer count is not less than min_buffer

Hi Ming Qian,

On 22/03/2022 09:28, Ming Qian wrote:
> the output buffer count should >= min_buffer_out
> the capture buffer count should >= min_buffer_cap
>
> Signed-off-by: Ming Qian <[email protected]>
> ---
> drivers/media/platform/amphion/vpu_v4l2.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/media/platform/amphion/vpu_v4l2.c b/drivers/media/platform/amphion/vpu_v4l2.c
> index cbf3315605a9..72a0544f4da3 100644
> --- a/drivers/media/platform/amphion/vpu_v4l2.c
> +++ b/drivers/media/platform/amphion/vpu_v4l2.c
> @@ -355,6 +355,10 @@ static int vpu_vb2_queue_setup(struct vb2_queue *vq,
> return 0;
> }
>
> + if (V4L2_TYPE_IS_OUTPUT(vq->type))
> + *buf_count = max_t(unsigned int, *buf_count, inst->min_buffer_out);
> + else
> + *buf_count = max_t(unsigned int, *buf_count, inst->min_buffer_cap);

I noticed that min_buffer_out/cap is set to 2, but min_buffers_needed
is set to 1. Wouldn't it make more sense to set min_buffers_needed to
2 as well?

If you do that, then the vb2 core will already take care of ensuring that
the buf_count is adjusted.

If you *do* have to do this manually, then you need to place the whole
if-else under 'if (!*num_planes) {', otherwise it will mess up the
VIDIOC_CREATE_BUFS ioctl. See the queue_setup in include/media/videobuf2-core.h
documentation for the sordid details.

Regards,

Hans

> *plane_count = cur_fmt->num_planes;
> for (i = 0; i < cur_fmt->num_planes; i++)
> psize[i] = cur_fmt->sizeimage[i];