Re: [PATCH] media: vb2: refactor setting flags and caps, fix missing cap

[Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>]

Le 16/01/2024 à 15:05, Hans Verkuil a écrit :
> Several functions implementing VIDIOC_REQBUFS and _CREATE_BUFS all use almost
> the same code to fill in the flags and capability fields. Refactor this into a
> new vb2_set_flags_and_caps() function that replaces the old fill_buf_caps()
> and validate_memory_flags() functions.
>
> This also fixes a bug where vb2_ioctl_create_bufs() would not set the
> V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS cap and also not fill in the
> max_num_buffers field.
>
> Fixes: d055a76c0065 ("media: core: Report the maximum possible number of buffers for the queue")
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>

Reviewed-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>

> ---
>   .../media/common/videobuf2/videobuf2-v4l2.c   | 55 +++++++++----------
>   1 file changed, 26 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 54d572c3b515..c575198e8354 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -671,8 +671,20 @@ int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
>   }
>   EXPORT_SYMBOL(vb2_querybuf);
>
> -static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
> +static void vb2_set_flags_and_caps(struct vb2_queue *q, u32 memory,
> +				   u32 *flags, u32 *caps, u32 *max_num_bufs)
>   {
> +	if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) {
> +		/*
> +		 * This needs to clear V4L2_MEMORY_FLAG_NON_COHERENT only,
> +		 * but in order to avoid bugs we zero out all bits.
> +		 */
> +		*flags = 0;
> +	} else {
> +		/* Clear all unknown flags. */
> +		*flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
> +	}
> +
>   	*caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
>   	if (q->io_modes & VB2_MMAP)
>   		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
> @@ -686,21 +698,9 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
>   		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS;
>   	if (q->supports_requests)
>   		*caps |= V4L2_BUF_CAP_SUPPORTS_REQUESTS;
> -}
> -
> -static void validate_memory_flags(struct vb2_queue *q,
> -				  int memory,
> -				  u32 *flags)
> -{
> -	if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) {
> -		/*
> -		 * This needs to clear V4L2_MEMORY_FLAG_NON_COHERENT only,
> -		 * but in order to avoid bugs we zero out all bits.
> -		 */
> -		*flags = 0;
> -	} else {
> -		/* Clear all unknown flags. */
> -		*flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
> +	if (max_num_bufs) {
> +		*max_num_bufs = q->max_num_buffers;
> +		*caps |= V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS;
>   	}
>   }
>
> @@ -709,8 +709,8 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
>   	int ret = vb2_verify_memory_type(q, req->memory, req->type);
>   	u32 flags = req->flags;
>
> -	fill_buf_caps(q, &req->capabilities);
> -	validate_memory_flags(q, req->memory, &flags);
> +	vb2_set_flags_and_caps(q, req->memory, &flags,
> +			       &req->capabilities, NULL);
>   	req->flags = flags;
>   	return ret ? ret : vb2_core_reqbufs(q, req->memory,
>   					    req->flags, &req->count);
> @@ -751,11 +751,9 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
>   	int ret = vb2_verify_memory_type(q, create->memory, f->type);
>   	unsigned i;
>
> -	fill_buf_caps(q, &create->capabilities);
> -	validate_memory_flags(q, create->memory, &create->flags);
>   	create->index = vb2_get_num_buffers(q);
> -	create->max_num_buffers = q->max_num_buffers;
> -	create->capabilities |= V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS;
> +	vb2_set_flags_and_caps(q, create->memory, &create->flags,
> +			       &create->capabilities, &create->max_num_buffers);
>   	if (create->count == 0)
>   		return ret != -EBUSY ? ret : 0;
>
> @@ -1006,8 +1004,8 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv,
>   	int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type);
>   	u32 flags = p->flags;
>
> -	fill_buf_caps(vdev->queue, &p->capabilities);
> -	validate_memory_flags(vdev->queue, p->memory, &flags);
> +	vb2_set_flags_and_caps(vdev->queue, p->memory, &flags,
> +			       &p->capabilities, NULL);
>   	p->flags = flags;
>   	if (res)
>   		return res;
> @@ -1026,12 +1024,11 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,
>   			  struct v4l2_create_buffers *p)
>   {
>   	struct video_device *vdev = video_devdata(file);
> -	int res = vb2_verify_memory_type(vdev->queue, p->memory,
> -			p->format.type);
> +	int res = vb2_verify_memory_type(vdev->queue, p->memory, p->format.type);
>
> -	p->index = vdev->queue->num_buffers;
> -	fill_buf_caps(vdev->queue, &p->capabilities);
> -	validate_memory_flags(vdev->queue, p->memory, &p->flags);
> +	p->index = vb2_get_num_buffers(vdev->queue);
> +	vb2_set_flags_and_caps(vdev->queue, p->memory, &p->flags,
> +			       &p->capabilities, &p->max_num_buffers);
>   	/*
>   	 * If count == 0, then just check if memory and type are valid.
>   	 * Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.