Re: [PATCH v2 12/17] media: atomisp: Fix VIDIOC_REQBUFS failing when VIDIOC_S_FMT has not been called yet

[Mauro Carvalho Chehab <mchehab@kernel.org>]

Em Thu, 20 Oct 2022 21:55:28 +0200
Hans de Goede <hdegoede@redhat.com> escreveu:

> camorama calls VIDIOC_REQBUFS(V4L2_MEMORY_MMAP) to test if MMAP support
> works (this was added specifically because of the previously broken
> MMAP support in atomisp).
> 
> Currently this fails because atomisp_get_css_frame_info() fails in this
> case. Although it is weird to call VIDIOC_REQBUFS before VIDIOC_S_FMT,
> it is allowed to do this.
> 
> Fix this not working by doing a S_FMT to V4L2_PIX_FMT_YUV420 + the highest
> supported resolution.
> 
> Note this will cause camorama to use mmap mode, which means it will also
> use libv4l2 to do format conversion. libv4l2 will pick V4L2_PIX_FMT_RGB565
> as input format and this will lead to a garbled video display. This is
> a libv4lconvert bug, the RGB565 -> RGB24 path in libv4lconvert assumes
> that stride == width which is not true on the atomisp.

Hmm... should we add a patch on Camorama for it to not use libv4l2 if
format == V4L2_PIX_FMT_RGB565?

> 
> I've already send out a libv4lconvert fix for this. Also this can be worked
> around by passing --dont-use-libv4l2 as argument to camorama.

Was the patch already applied? The better would be to apply it at
libv4l2 upstream, as a fix, porting it to old versions, and mentioning
on what versions this got fixed on this changeset.

> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  .../media/atomisp/pci/atomisp_compat_css20.c  |  2 +-
>  .../staging/media/atomisp/pci/atomisp_fops.c  | 25 +++++++++++++++++--
>  2 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c b/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c
> index ea6114679c53..f282572d69da 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c
> @@ -2688,7 +2688,7 @@ int atomisp_get_css_frame_info(struct atomisp_sub_device *asd,
>  
>  	if (0 != ia_css_pipe_get_info(asd->stream_env[stream_index]
>  		.pipes[pipe_index], &info)) {
> -		dev_err(isp->dev, "ia_css_pipe_get_info FAILED");
> +		dev_dbg(isp->dev, "ia_css_pipe_get_info FAILED");
>  		return -EINVAL;
>  	}
>  
> diff --git a/drivers/staging/media/atomisp/pci/atomisp_fops.c b/drivers/staging/media/atomisp/pci/atomisp_fops.c
> index bc47a092a8af..f539df09ebd9 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_fops.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_fops.c
> @@ -50,15 +50,36 @@ static int atomisp_queue_setup(struct vb2_queue *vq,
>  	u16 source_pad = atomisp_subdev_source_pad(&pipe->vdev);
>  	int ret;
>  
> +	mutex_lock(&pipe->asd->isp->mutex); /* for get_css_frame_info() / set_fmt() */
> +
> +	/*
> +	 * When VIDIOC_S_FMT has not been called before VIDIOC_REQBUFS, then
> +	 * this will fail. Call atomisp_set_fmt() ourselves and try again.
> +	 */
>  	ret = atomisp_get_css_frame_info(pipe->asd, source_pad, &pipe->frame_info);
> -	if (ret)
> -		return ret;
> +	if (ret) {
> +		struct v4l2_format f = {
> +			.fmt.pix.pixelformat = V4L2_PIX_FMT_YUV420,
> +			.fmt.pix.width = 10000,
> +			.fmt.pix.height = 10000,
> +		};
> +
> +		ret = atomisp_set_fmt(&pipe->vdev, &f);
> +		if (ret)
> +			goto out;
> +
> +		ret = atomisp_get_css_frame_info(pipe->asd, source_pad, &pipe->frame_info);
> +		if (ret)
> +			goto out;
> +	}
>  
>  	atomisp_alloc_css_stat_bufs(pipe->asd, ATOMISP_INPUT_STREAM_GENERAL);
>  
>  	*nplanes = 1;
>  	sizes[0] = PAGE_ALIGN(pipe->pix.sizeimage);
>  
> +out:
> +	mutex_unlock(&pipe->asd->isp->mutex);
>  	return 0;
>  }
>