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

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Hi Guennadi,

On Monday, 11 December 2017 23:44:09 EET Guennadi Liakhovetski wrote:
> On Mon, 11 Dec 2017, Laurent Pinchart wrote:
> > 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@xxxxxxxxx>
> >>> 
> >>> 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@xxxxxxxxx>
> >>> ---
> >>> 
> >>> 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.
> Sure, thanks for catching! Shall I fix and resubmit?

If you're fine with

	git://linuxtv.org/pinchartl/media.git uvc/next

there's no need to resubmit.

By the way, could you please review "uvcvideo: Factor out video device 
registration to a function" and "uvcvideo: Report V4L2 device caps through the 
video_device structure" ?

I will send a pull request after testing the code and getting those two 
patches reviewed.

> >> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >> 
> >> Would you mind sending me your test tool patch ?
> 
> Will send it offline.
> 
> Thanks
> Guennadi
> 
> >> 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




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