Re: [PATCH v8] uvcvideo: Add a metadata device node

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Guennadi,

On Monday, 11 December 2017 22:16:23 EET Laurent Pinchart wrote:
> On Wednesday, 6 December 2017 17:15:40 EET Guennadi Liakhovetski wrote:
> > From: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
> > 
> > Some UVC video cameras contain metadata in their payload headers. This
> > patch extracts that data, adding more clock synchronisation information,
> > on both bulk and isochronous endpoints and makes it available to the user
> > space on a separate video node, using the V4L2_CAP_META_CAPTURE capability
> > and the V4L2_BUF_TYPE_META_CAPTURE buffer queue type. By default, only the
> > V4L2_META_FMT_UVC pixel format is available from those nodes. However,
> > cameras can be added to the device ID table to additionally specify their
> > own metadata format, in which case that format will also become available
> > from the metadata node.
> > 
> > Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
> > ---
> > 
> > v8: addressed comments and integrated changes from Laurent, thanks again,
> > e.g.:
> > 
> > - multiple stylistic changes
> > - remove the UVC_DEV_FLAG_METADATA_NODE flag / quirk: nodes are now
> >   created unconditionally
> > - reuse uvc_ioctl_querycap()
> > - reuse code in uvc_register_video()
> > - set an error flag when the metadata buffer overflows
> > 
> >  drivers/media/usb/uvc/Makefile       |   2 +-
> >  drivers/media/usb/uvc/uvc_driver.c   |  15 ++-
> >  drivers/media/usb/uvc/uvc_isight.c   |   2 +-
> >  drivers/media/usb/uvc/uvc_metadata.c | 179 ++++++++++++++++++++++++++++++
> >  drivers/media/usb/uvc/uvc_queue.c    |  44 +++++++--
> >  drivers/media/usb/uvc/uvc_video.c    | 132 ++++++++++++++++++++++++--
> >  drivers/media/usb/uvc/uvcvideo.h     |  16 +++-
> >  include/uapi/linux/uvcvideo.h        |  26 +++++
> >  8 files changed, 394 insertions(+), 22 deletions(-)
> >  create mode 100644 drivers/media/usb/uvc/uvc_metadata.c
> 
> [snip]
> 
> > diff --git a/drivers/media/usb/uvc/uvc_video.c
> > b/drivers/media/usb/uvc/uvc_video.c index 13f459e..2fc0bf2 100644
> > --- a/drivers/media/usb/uvc/uvc_video.c
> > +++ b/drivers/media/usb/uvc/uvc_video.c
> 
> [snip]
> 
> > +static void uvc_video_decode_meta(struct uvc_streaming *stream,
> > +				  struct uvc_buffer *meta_buf,
> > +				  const u8 *mem, unsigned int length)
> > +{
> > +	struct uvc_meta_buf *meta;
> > +	size_t len_std = 2;
> > +	bool has_pts, has_scr;
> > +	unsigned long flags;
> > +	ktime_t time;
> > +	const u8 *scr;
> > +
> > +	if (!meta_buf || length == 2)
> > +		return;
> > +
> > +	if (meta_buf->length - meta_buf->bytesused <
> > +	    length + sizeof(meta->ns) + sizeof(meta->sof)) {
> > +		meta_buf->error = 1;
> > +		return;
> > +	}
> > +
> > +	has_pts = mem[1] & UVC_STREAM_PTS;
> > +	has_scr = mem[1] & UVC_STREAM_SCR;
> > +
> > +	if (has_pts) {
> > +		len_std += 4;
> > +		scr = mem + 6;
> > +	} else {
> > +		scr = mem + 2;
> > +	}
> > +
> > +	if (has_scr)
> > +		len_std += 6;
> > +
> > +	if (stream->meta.format == V4L2_META_FMT_UVC)
> > +		length = len_std;
> > +
> > +	if (length == len_std && (!has_scr ||
> > +				  !memcmp(scr, stream->clock.last_scr, 6)))
> > +		return;
> > +
> > +	meta = (struct uvc_meta_buf *)((u8 *)meta_buf->mem +
> > meta_buf->bytesused); +	local_irq_save(flags);
> > +	time = uvc_video_get_time();
> > +	meta->sof = usb_get_current_frame_number(stream->dev->udev);
> 
> You need a put_unaligned here too. If you're fine with the patch below
> there's no need to resubmit, and

One more thing, __put_unaligned_cpu16() and __put_unaligned_cpu64() don't 
compile on x86_64 with v4.12 (using media_build.git). I propose replacing them 
with put_unaligned() which compiles and should do the right thing.

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> Would you mind sending me your test tool patch ?
> 
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/
> uvc_video.c
> index 2fc0bf2221db..02e4997a32bb 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1142,6 +1142,7 @@ static void uvc_video_decode_meta(struct uvc_streaming
> *stream,
>  	size_t len_std = 2;
>  	bool has_pts, has_scr;
>  	unsigned long flags;
> +	unsigned int sof;
>  	ktime_t time;
>  	const u8 *scr;
> 
> @@ -1177,9 +1178,10 @@ static void uvc_video_decode_meta(struct
> uvc_streaming *stream,
>  	meta = (struct uvc_meta_buf *)((u8 *)meta_buf->mem + meta_buf->bytesused);
> local_irq_save(flags);
>  	time = uvc_video_get_time();
> -	meta->sof = usb_get_current_frame_number(stream->dev->udev);
> +	sof = usb_get_current_frame_number(stream->dev->udev);
>  	local_irq_restore(flags);
>  	__put_unaligned_cpu64(ktime_to_ns(time), &meta->ns);
> +	__put_unaligned_cpu16(sof, &meta->sof);
> 
>  	if (has_scr)
>  		memcpy(stream->clock.last_scr, scr, 6);
> 
> > +	local_irq_restore(flags);
> > +	__put_unaligned_cpu64(ktime_to_ns(time), &meta->ns);
> > +
> > +	if (has_scr)
> > +		memcpy(stream->clock.last_scr, scr, 6);
> > +
> > +	memcpy(&meta->length, mem, length);
> > +	meta_buf->bytesused += length + sizeof(meta->ns) + sizeof(meta->sof);
> > +
> > +	uvc_trace(UVC_TRACE_FRAME,
> > +		  "%s(): t-sys %lluns, SOF %u, len %u, flags 0x%x, PTS %u, STC %u 
frame
> > SOF %u\n", +		  __func__, time, meta->sof, meta->length, meta->flags,
> > +		  has_pts ? *(u32 *)meta->buf : 0,
> > +		  has_scr ? *(u32 *)scr : 0,
> > +		  has_scr ? *(u32 *)(scr + 4) & 0x7ff : 0);
> > +}
> 
> [snip]

-- 
Regards,

Laurent Pinchart