linux-kernel - Re: [PATCH 8/8] media: cedrus: Add support for V4L2_DEC_CMD

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Date:   Thu, 29 Aug 2019 13:11:46 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Jernej Skrabec <jernej.skrabec@...l.net>, mchehab@...nel.org,
        paul.kocialkowski@...tlin.com, mripard@...nel.org
Cc:     pawel@...iak.com, m.szyprowski@...sung.com,
        kyungmin.park@...sung.com, tfiga@...omium.org, wens@...e.org,
        acourbot@...omium.org, gregkh@...uxfoundation.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devel@...verdev.osuosl.org, linux-arm-kernel@...ts.infradead.org,
        ezequiel@...labora.com, jonas@...boo.se
Subject: Re: [PATCH 8/8] media: cedrus: Add support for V4L2_DEC_CMD_FLUSH

On 8/22/19 9:45 PM, Jernej Skrabec wrote:
> This command is useful for explicitly flushing last decoded frame.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
> ---
>  .../staging/media/sunxi/cedrus/cedrus_video.c | 34 +++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_video.c b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> index 5153b2bba21e..9eae69d5741c 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> @@ -331,6 +331,37 @@ static int cedrus_s_fmt_vid_out(struct file *file, void *priv,
>  	return 0;
>  }
>  
> +static int cedrus_try_decoder_cmd(struct file *file, void *fh,
> +				  struct v4l2_decoder_cmd *dc)
> +{
> +	if (dc->cmd != V4L2_DEC_CMD_FLUSH)
> +		return -EINVAL;

You need to add this line here as well:

	dc->flags = 0;

As per the decoder_cmd spec.

> +
> +	return 0;
> +}
> +
> +static int cedrus_decoder_cmd(struct file *file, void *fh,
> +			      struct v4l2_decoder_cmd *dc)
> +{
> +	struct cedrus_ctx *ctx = cedrus_file2ctx(file);

You don't need this...

> +	struct vb2_v4l2_buffer *out_vb, *cap_vb;
> +	int ret;
> +
> +	ret = cedrus_try_decoder_cmd(file, fh, dc);
> +	if (ret < 0)
> +		return ret;
> +
> +	out_vb = v4l2_m2m_last_src_buf(ctx->fh.m2m_ctx);

... since you can use fh->m2m_ctx directly.

> +	cap_vb = v4l2_m2m_last_dst_buf(ctx->fh.m2m_ctx);
> +
> +	if (out_vb)
> +		out_vb->flags &= ~V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
> +	else if (cap_vb && cap_vb->is_held)
> +		v4l2_m2m_buf_done(cap_vb, VB2_BUF_STATE_DONE);
> +
> +	return 0;
> +}
> +

Both these functions should be moved to v4l2-mem2mem.c and renamed to
v4l2_m2m_ioctl_stateless_(try_)decoder_cmd.

As far as I can see they are completely generic and valid for any
stateless decoder. Which is very nice :-)

>  const struct v4l2_ioctl_ops cedrus_ioctl_ops = {
>  	.vidioc_querycap		= cedrus_querycap,
>  
> @@ -355,6 +386,9 @@ const struct v4l2_ioctl_ops cedrus_ioctl_ops = {
>  	.vidioc_streamon		= v4l2_m2m_ioctl_streamon,
>  	.vidioc_streamoff		= v4l2_m2m_ioctl_streamoff,
>  
> +	.vidioc_try_decoder_cmd		= cedrus_try_decoder_cmd,
> +	.vidioc_decoder_cmd		= cedrus_decoder_cmd,
> +
>  	.vidioc_subscribe_event		= v4l2_ctrl_subscribe_event,
>  	.vidioc_unsubscribe_event	= v4l2_event_unsubscribe,
>  };
> 

Regards,

	Hans