[PATCH v4] uvcvideo: add a metadata device node

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

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. Even
though different cameras will have different metadata formats, we use
the same V4L2_META_FMT_UVC pixel format for all of them. Users have to
parse data, based on the specific camera model information. This
version of the patch only creates such metadata nodes for cameras,
specifying a UVC_QUIRK_METADATA_NODE quirk flag.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
---

v4:
- add support for isochronous cameras. Metadata is now collected from as 
many payloads as they fit in the buffer
- add a USB Start Of Frame and a system timestamp to each metadata block 
for user-space clock synchronisation
- use a default buffer size of 1024 bytes

Thanks to Laurent for patient long discussions and to everybody, who 
helped me conduct all the investigation into various past, present and 
future UVC cameras :-)

 drivers/media/usb/uvc/Makefile       |   2 +-
 drivers/media/usb/uvc/uvc_driver.c   |   4 +
 drivers/media/usb/uvc/uvc_isight.c   |   2 +-
 drivers/media/usb/uvc/uvc_metadata.c | 158 +++++++++++++++++++++++++++++++++++
 drivers/media/usb/uvc/uvc_queue.c    |  68 ++++++++++-----
 drivers/media/usb/uvc/uvc_video.c    | 101 +++++++++++++++++++---
 drivers/media/usb/uvc/uvcvideo.h     |  23 ++++-
 drivers/media/v4l2-core/v4l2-ioctl.c |   1 +
 include/uapi/linux/uvcvideo.h        |  19 +++++
 include/uapi/linux/videodev2.h       |   3 +
 10 files changed, 347 insertions(+), 34 deletions(-)
 create mode 100644 drivers/media/usb/uvc/uvc_metadata.c

diff --git a/drivers/media/usb/uvc/Makefile b/drivers/media/usb/uvc/Makefile
index c26d12f..06c7cd3 100644
--- a/drivers/media/usb/uvc/Makefile
+++ b/drivers/media/usb/uvc/Makefile
@@ -1,5 +1,5 @@
 uvcvideo-objs  := uvc_driver.o uvc_queue.o uvc_v4l2.o uvc_video.o uvc_ctrl.o \
-		  uvc_status.o uvc_isight.o uvc_debugfs.o
+		  uvc_status.o uvc_isight.o uvc_debugfs.o uvc_metadata.o
 ifeq ($(CONFIG_MEDIA_CONTROLLER),y)
 uvcvideo-objs  += uvc_entity.o
 endif
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 70842c5..9f23dcf 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1880,6 +1880,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
 			continue;
 
 		video_unregister_device(&stream->vdev);
+		video_unregister_device(&stream->meta.vdev);
 
 		uvc_debugfs_cleanup_stream(stream);
 	}
@@ -1941,6 +1942,9 @@ static int uvc_register_video(struct uvc_device *dev,
 		return ret;
 	}
 
+	/* Register a metadata node. */
+	uvc_meta_register(stream);
+
 	if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
 		stream->chain->caps |= V4L2_CAP_VIDEO_CAPTURE;
 	else
diff --git a/drivers/media/usb/uvc/uvc_isight.c b/drivers/media/usb/uvc/uvc_isight.c
index 8510e725..fb940cf 100644
--- a/drivers/media/usb/uvc/uvc_isight.c
+++ b/drivers/media/usb/uvc/uvc_isight.c
@@ -100,7 +100,7 @@ static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf,
 }
 
 void uvc_video_decode_isight(struct urb *urb, struct uvc_streaming *stream,
-		struct uvc_buffer *buf)
+			struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
 {
 	int ret, i;
 
diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
new file mode 100644
index 0000000..876badd
--- /dev/null
+++ b/drivers/media/usb/uvc/uvc_metadata.c
@@ -0,0 +1,158 @@
+/*
+ *      uvc_metadata.c  --  USB Video Class driver - Metadata handling
+ *
+ *      Copyright (C) 2016
+ *          Guennadi Liakhovetski (guennadi.liakhovetski@intel.com)
+ *
+ *      This program is free software; you can redistribute it and/or modify
+ *      it under the terms of the GNU General Public License as published by
+ *      the Free Software Foundation; either version 2 of the License, or
+ *      (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/videodev2.h>
+
+#include <media/v4l2-ioctl.h>
+#include <media/videobuf2-v4l2.h>
+#include <media/videobuf2-vmalloc.h>
+
+#include "uvcvideo.h"
+
+/* -----------------------------------------------------------------------------
+ * videobuf2 Queue Operations
+ */
+
+static struct vb2_ops uvc_meta_queue_ops = {
+	.queue_setup = uvc_queue_setup,
+	.buf_prepare = uvc_buffer_prepare,
+	.buf_queue = uvc_buffer_queue,
+	.wait_prepare = vb2_ops_wait_prepare,
+	.wait_finish = vb2_ops_wait_finish,
+	.stop_streaming = uvc_stop_streaming,
+};
+
+/* -----------------------------------------------------------------------------
+ * V4L2 ioctls
+ */
+
+static int meta_v4l2_querycap(struct file *file, void *fh,
+			      struct v4l2_capability *cap)
+{
+	struct v4l2_fh *vfh = file->private_data;
+	struct uvc_streaming *stream = video_get_drvdata(vfh->vdev);
+
+	strlcpy(cap->driver, "uvcvideo", sizeof(cap->driver));
+	strlcpy(cap->card, vfh->vdev->name, sizeof(cap->card));
+	usb_make_path(stream->dev->udev, cap->bus_info, sizeof(cap->bus_info));
+
+	return 0;
+}
+
+static int meta_v4l2_get_format(struct file *file, void *fh,
+				struct v4l2_format *format)
+{
+	struct v4l2_fh *vfh = file->private_data;
+	struct v4l2_meta_format *fmt = &format->fmt.meta;
+
+	if (format->type != vfh->vdev->queue->type)
+		return -EINVAL;
+
+	memset(fmt, 0, sizeof(*fmt));
+
+	fmt->dataformat = V4L2_META_FMT_UVC;
+	fmt->buffersize = UVC_METATADA_BUF_SIZE;
+
+	return 0;
+}
+
+static const struct v4l2_ioctl_ops uvc_meta_ioctl_ops = {
+	.vidioc_querycap		= meta_v4l2_querycap,
+	.vidioc_g_fmt_meta_cap		= meta_v4l2_get_format,
+	.vidioc_s_fmt_meta_cap		= meta_v4l2_get_format,
+	.vidioc_try_fmt_meta_cap	= meta_v4l2_get_format,
+	.vidioc_reqbufs			= vb2_ioctl_reqbufs,
+	.vidioc_querybuf		= vb2_ioctl_querybuf,
+	.vidioc_qbuf			= vb2_ioctl_qbuf,
+	.vidioc_dqbuf			= vb2_ioctl_dqbuf,
+	.vidioc_create_bufs		= vb2_ioctl_create_bufs,
+	.vidioc_prepare_buf		= vb2_ioctl_prepare_buf,
+	.vidioc_streamon		= vb2_ioctl_streamon,
+	.vidioc_streamoff		= vb2_ioctl_streamoff,
+};
+
+/* -----------------------------------------------------------------------------
+ * V4L2 File Operations
+ */
+
+static struct v4l2_file_operations uvc_meta_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = video_ioctl2,
+	.open = v4l2_fh_open,
+	.release = vb2_fop_release,
+	.poll = vb2_fop_poll,
+	.mmap = vb2_fop_mmap,
+};
+
+int uvc_meta_register(struct uvc_streaming *stream)
+{
+	struct uvc_device *dev = stream->dev;
+	struct uvc_meta_device *meta = &stream->meta;
+	struct video_device *vdev = &meta->vdev;
+	struct uvc_video_queue *quvc = &meta->queue;
+	struct vb2_queue *queue = &quvc->queue;
+	int ret;
+
+	mutex_init(&quvc->mutex);
+	spin_lock_init(&quvc->irqlock);
+	INIT_LIST_HEAD(&quvc->irqqueue);
+
+	/*
+	 * We register metadata device nodes only if the METADATA_NODE quirk is
+	 * set and only on interfaces with bulk endpoints. To meaningfully
+	 * support interfaces with isochronous endpoints, we need to collect
+	 * headers from all payloads, comprising a single frame. For that we
+	 * need to know the maximum number of such payloads per frame to be able
+	 * to calculate the buffer size. Currently this information is
+	 * unavailable. A proposal should be made to the UVC committee to add
+	 * this information to camera descriptors.
+	 */
+	if (!(dev->quirks & UVC_QUIRK_METADATA_NODE) ||
+	    dev->quirks & UVC_QUIRK_BUILTIN_ISIGHT)
+		return 0;
+
+	vdev->v4l2_dev = &dev->vdev;
+	vdev->fops = &uvc_meta_fops;
+	vdev->ioctl_ops = &uvc_meta_ioctl_ops;
+	vdev->release = video_device_release_empty;
+	vdev->prio = &stream->chain->prio;
+	vdev->vfl_dir = VFL_DIR_RX;
+	vdev->queue = queue;
+	vdev->device_caps = V4L2_CAP_META_CAPTURE | V4L2_CAP_STREAMING;
+	strlcpy(vdev->name, dev->name, sizeof(vdev->name));
+
+	video_set_drvdata(vdev, stream);
+
+	/* Initialize the video buffer queue. */
+	queue->type = V4L2_BUF_TYPE_META_CAPTURE;
+	queue->io_modes = VB2_MMAP | VB2_USERPTR;
+	queue->drv_priv = quvc;
+	queue->buf_struct_size = sizeof(struct uvc_buffer);
+	queue->ops = &uvc_meta_queue_ops;
+	queue->mem_ops = &vb2_vmalloc_memops;
+	queue->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
+		| V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
+	queue->lock = &quvc->mutex;
+	ret = vb2_queue_init(queue);
+	if (ret < 0)
+		return ret;
+
+	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
+	if (ret < 0)
+		uvc_printk(KERN_ERR, "Failed to register metadata device (%d).\n", ret);
+
+	return ret;
+}
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index aa21997..77dedbc 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -74,13 +74,26 @@ static void uvc_queue_return_buffers(struct uvc_video_queue *queue,
  * videobuf2 queue operations
  */
 
-static int uvc_queue_setup(struct vb2_queue *vq,
-			   unsigned int *nbuffers, unsigned int *nplanes,
-			   unsigned int sizes[], struct device *alloc_devs[])
+int uvc_queue_setup(struct vb2_queue *vq,
+		    unsigned int *nbuffers, unsigned int *nplanes,
+		    unsigned int sizes[], struct device *alloc_devs[])
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
-	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
-	unsigned size = stream->ctrl.dwMaxVideoFrameSize;
+	struct uvc_streaming *stream;
+	unsigned int size;
+
+	switch (vq->type) {
+	case V4L2_BUF_TYPE_META_CAPTURE:
+		size = UVC_METATADA_BUF_SIZE;
+
+		if (*nplanes && *nplanes != 1)
+			return -EINVAL;
+
+		break;
+	default:
+		stream = uvc_queue_to_stream(queue);
+		size = stream->ctrl.dwMaxVideoFrameSize;
+	}
 
 	/* Make sure the image size is large enough. */
 	if (*nplanes)
@@ -90,34 +103,47 @@ static int uvc_queue_setup(struct vb2_queue *vq,
 	return 0;
 }
 
-static int uvc_buffer_prepare(struct vb2_buffer *vb)
+int uvc_buffer_prepare(struct vb2_buffer *vb)
 {
 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
 	struct uvc_buffer *buf = uvc_vbuf_to_buffer(vbuf);
 
-	if (vb->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
-	    vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
-		uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
-		return -EINVAL;
-	}
-
 	if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
 		return -ENODEV;
 
+	switch (vb->type) {
+	case V4L2_BUF_TYPE_VIDEO_OUTPUT:
+		if (vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
+			uvc_trace(UVC_TRACE_CAPTURE,
+				  "[E] Bytes used out of bounds.\n");
+			return -EINVAL;
+		}
+
+		buf->bytesused = vb2_get_plane_payload(vb, 0);
+
+		break;
+	case V4L2_BUF_TYPE_META_CAPTURE:
+		if (vb->num_planes != 1 ||
+		    vb2_plane_size(vb, 0) < UVC_METATADA_BUF_SIZE) {
+			uvc_trace(UVC_TRACE_CAPTURE,
+				  "[E] Invalid buffer configuration.\n");
+			return -EINVAL;
+		}
+		/* Fall through */
+	default:
+		buf->bytesused = 0;
+	}
+
 	buf->state = UVC_BUF_STATE_QUEUED;
 	buf->error = 0;
 	buf->mem = vb2_plane_vaddr(vb, 0);
 	buf->length = vb2_plane_size(vb, 0);
-	if (vb->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
-		buf->bytesused = 0;
-	else
-		buf->bytesused = vb2_get_plane_payload(vb, 0);
 
 	return 0;
 }
 
-static void uvc_buffer_queue(struct vb2_buffer *vb)
+void uvc_buffer_queue(struct vb2_buffer *vb)
 {
 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
@@ -169,13 +195,15 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 	return ret;
 }
 
-static void uvc_stop_streaming(struct vb2_queue *vq)
+void uvc_stop_streaming(struct vb2_queue *vq)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
-	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
 	unsigned long flags;
 
-	uvc_video_enable(stream, 0);
+	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) {
+		struct uvc_streaming *stream = uvc_queue_to_stream(queue);
+		uvc_video_enable(stream, 0);
+	}
 
 	spin_lock_irqsave(&queue->irqlock, flags);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index fb86d6a..3a54439 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1152,8 +1152,76 @@ static void uvc_video_validate_buffer(const struct uvc_streaming *stream,
 /*
  * Completion handler for video URBs.
  */
+
+static void uvc_video_decode_meta(struct uvc_streaming *stream,
+			struct uvc_buffer *buf, struct uvc_buffer *meta_buf,
+			u8 *mem, unsigned int length)
+{
+	struct uvc_meta_buf *meta;
+	size_t len_std = 2;
+	bool has_pts, has_scr;
+	u8 *scr;
+
+	if (!meta_buf || length == 2 ||
+	    meta_buf->length - meta_buf->bytesused <
+	    length + sizeof(meta->ts) + sizeof(meta->sof) ||
+	    length != mem[0])
+		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 (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);
+	uvc_video_get_ts(&meta->ts);
+	meta->sof = usb_get_current_frame_number(stream->dev->udev);
+
+	if (!meta_buf->bytesused) {
+		meta_buf->buf.sequence = buf->buf.sequence;
+		meta_buf->buf.field = buf->buf.field;
+		meta_buf->buf.vb2_buf.timestamp = buf->buf.vb2_buf.timestamp;
+	}
+
+	if (has_scr)
+		memcpy(stream->clock.last_scr, scr, 6);
+
+	memcpy(&meta->length, mem, length);
+	meta_buf->bytesused += length + sizeof(meta->ts) + sizeof(meta->sof);
+
+	uvc_trace(UVC_TRACE_FRAME,
+		  "%s(): t-sys %lu.%09lus, SOF %u, len %u, flags 0x%x, PTS %u, STC %u frame SOF %u\n",
+		  __func__, meta->ts.tv_sec, meta->ts.tv_nsec, meta->sof,
+		  meta->length, meta->flags, has_pts ? *(u32 *)meta->buf : 0,
+		  has_scr ? *(u32 *)scr : 0,
+		  has_scr ? *(u32 *)(scr + 4) & 0x7ff : 0);
+}
+
+static struct uvc_buffer *uvc_video_step_buffers(struct uvc_streaming *stream,
+			struct uvc_buffer *buf, struct uvc_buffer **meta_buf)
+{
+	if (*meta_buf) {
+		(*meta_buf)->state = UVC_BUF_STATE_READY;
+		*meta_buf = uvc_queue_next_buffer(&stream->meta.queue,
+						  *meta_buf);
+	}
+	return uvc_queue_next_buffer(&stream->queue, buf);
+}
+
 static void uvc_video_decode_isoc(struct urb *urb, struct uvc_streaming *stream,
-	struct uvc_buffer *buf)
+			struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
 {
 	u8 *mem;
 	int ret, i;
@@ -1175,14 +1243,16 @@ static void uvc_video_decode_isoc(struct urb *urb, struct uvc_streaming *stream,
 				urb->iso_frame_desc[i].actual_length);
 			if (ret == -EAGAIN) {
 				uvc_video_validate_buffer(stream, buf);
-				buf = uvc_queue_next_buffer(&stream->queue,
-							    buf);
+				buf = uvc_video_step_buffers(stream, buf,
+							     &meta_buf);
 			}
 		} while (ret == -EAGAIN);
 
 		if (ret < 0)
 			continue;
 
+		uvc_video_decode_meta(stream, buf, meta_buf, mem, ret);
+
 		/* Decode the payload data. */
 		uvc_video_decode_data(stream, buf, mem + ret,
 			urb->iso_frame_desc[i].actual_length - ret);
@@ -1193,13 +1263,13 @@ static void uvc_video_decode_isoc(struct urb *urb, struct uvc_streaming *stream,
 
 		if (buf->state == UVC_BUF_STATE_READY) {
 			uvc_video_validate_buffer(stream, buf);
-			buf = uvc_queue_next_buffer(&stream->queue, buf);
+			buf = uvc_video_step_buffers(stream, buf, &meta_buf);
 		}
 	}
 }
 
 static void uvc_video_decode_bulk(struct urb *urb, struct uvc_streaming *stream,
-	struct uvc_buffer *buf)
+			struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
 {
 	u8 *mem;
 	int len, ret;
@@ -1222,8 +1292,8 @@ static void uvc_video_decode_bulk(struct urb *urb, struct uvc_streaming *stream,
 		do {
 			ret = uvc_video_decode_start(stream, buf, mem, len);
 			if (ret == -EAGAIN)
-				buf = uvc_queue_next_buffer(&stream->queue,
-							    buf);
+				buf = uvc_video_step_buffers(stream, buf,
+							     &meta_buf);
 		} while (ret == -EAGAIN);
 
 		/* If an error occurred skip the rest of the payload. */
@@ -1233,6 +1303,8 @@ static void uvc_video_decode_bulk(struct urb *urb, struct uvc_streaming *stream,
 			memcpy(stream->bulk.header, mem, ret);
 			stream->bulk.header_size = ret;
 
+			uvc_video_decode_meta(stream, buf, meta_buf, mem, ret);
+
 			mem += ret;
 			len -= ret;
 		}
@@ -1256,7 +1328,7 @@ static void uvc_video_decode_bulk(struct urb *urb, struct uvc_streaming *stream,
 			uvc_video_decode_end(stream, buf, stream->bulk.header,
 				stream->bulk.payload_size);
 			if (buf->state == UVC_BUF_STATE_READY)
-				uvc_queue_next_buffer(&stream->queue, buf);
+				uvc_video_step_buffers(stream, buf, &meta_buf);
 		}
 
 		stream->bulk.header_size = 0;
@@ -1266,7 +1338,7 @@ static void uvc_video_decode_bulk(struct urb *urb, struct uvc_streaming *stream,
 }
 
 static void uvc_video_encode_bulk(struct urb *urb, struct uvc_streaming *stream,
-	struct uvc_buffer *buf)
+	struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
 {
 	u8 *mem = urb->transfer_buffer;
 	int len = stream->urb_size, ret;
@@ -1312,7 +1384,9 @@ static void uvc_video_complete(struct urb *urb)
 {
 	struct uvc_streaming *stream = urb->context;
 	struct uvc_video_queue *queue = &stream->queue;
+	struct uvc_video_queue *qmeta = &stream->meta.queue;
 	struct uvc_buffer *buf = NULL;
+	struct uvc_buffer *buf_meta = NULL;
 	unsigned long flags;
 	int ret;
 
@@ -1331,6 +1405,7 @@ static void uvc_video_complete(struct urb *urb)
 	case -ECONNRESET:	/* usb_unlink_urb() called. */
 	case -ESHUTDOWN:	/* The endpoint is being disabled. */
 		uvc_queue_cancel(queue, urb->status == -ESHUTDOWN);
+		uvc_queue_cancel(qmeta, urb->status == -ESHUTDOWN);
 		return;
 	}
 
@@ -1340,7 +1415,13 @@ static void uvc_video_complete(struct urb *urb)
 				       queue);
 	spin_unlock_irqrestore(&queue->irqlock, flags);
 
-	stream->decode(urb, stream, buf);
+	spin_lock_irqsave(&qmeta->irqlock, flags);
+	if (!list_empty(&qmeta->irqqueue))
+		buf_meta = list_first_entry(&qmeta->irqqueue, struct uvc_buffer,
+					    queue);
+	spin_unlock_irqrestore(&qmeta->irqlock, flags);
+
+	stream->decode(urb, stream, buf, buf_meta);
 
 	if ((ret = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
 		uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n",
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 15e415e..d06e2d6 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -185,6 +185,7 @@
 #define UVC_QUIRK_RESTRICT_FRAME_RATE	0x00000200
 #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT	0x00000400
 #define UVC_QUIRK_FORCE_Y8		0x00000800
+#define UVC_QUIRK_METADATA_NODE		0x00001000
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001
@@ -473,6 +474,13 @@ struct uvc_stats_stream {
 	unsigned int max_sof;		/* Maximum STC.SOF value */
 };
 
+struct uvc_meta_device {
+	struct video_device vdev;
+	struct uvc_video_queue queue;
+};
+
+#define UVC_METATADA_BUF_SIZE 1024
+
 struct uvc_streaming {
 	struct list_head list;
 	struct uvc_device *dev;
@@ -504,7 +512,9 @@ struct uvc_streaming {
 	unsigned int frozen : 1;
 	struct uvc_video_queue queue;
 	void (*decode) (struct urb *urb, struct uvc_streaming *video,
-			struct uvc_buffer *buf);
+			struct uvc_buffer *buf, struct uvc_buffer *meta_buf);
+
+	struct uvc_meta_device meta;
 
 	/* Context data used by the bulk completion handler. */
 	struct {
@@ -546,6 +556,8 @@ struct uvc_streaming {
 		u16 last_sof;
 		u16 sof_offset;
 
+		u8 last_scr[6];
+
 		spinlock_t lock;
 	} clock;
 };
@@ -684,6 +696,12 @@ extern unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
 		unsigned long pgoff);
 #endif
 extern int uvc_queue_allocated(struct uvc_video_queue *queue);
+extern int uvc_queue_setup(struct vb2_queue *vq,
+			   unsigned int *nbuffers, unsigned int *nplanes,
+			   unsigned int sizes[], struct device *alloc_devs[]);
+extern int uvc_buffer_prepare(struct vb2_buffer *vb);
+extern void uvc_buffer_queue(struct vb2_buffer *vb);
+extern void uvc_stop_streaming(struct vb2_queue *vq);
 static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
 {
 	return vb2_is_streaming(&queue->queue);
@@ -709,6 +727,7 @@ extern int uvc_query_ctrl(struct uvc_device *dev, __u8 query, __u8 unit,
 void uvc_video_clock_update(struct uvc_streaming *stream,
 			    struct vb2_v4l2_buffer *vbuf,
 			    struct uvc_buffer *buf);
+int uvc_meta_register(struct uvc_streaming *stream);
 
 /* Status */
 extern int uvc_status_init(struct uvc_device *dev);
@@ -763,7 +782,7 @@ extern struct usb_host_endpoint *uvc_find_endpoint(
 
 /* Quirks support */
 void uvc_video_decode_isight(struct urb *urb, struct uvc_streaming *stream,
-		struct uvc_buffer *buf);
+		struct uvc_buffer *buf, struct uvc_buffer *meta_buf);
 
 /* debugfs and statistics */
 void uvc_debugfs_init(void);
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index cab63bb..0fd0ac2 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1239,6 +1239,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
 	case V4L2_TCH_FMT_TU08:		descr = "8-bit unsigned touch data"; break;
 	case V4L2_META_FMT_VSP1_HGO:	descr = "R-Car VSP1 1-D Histogram"; break;
 	case V4L2_META_FMT_VSP1_HGT:	descr = "R-Car VSP1 2-D Histogram"; break;
+	case V4L2_META_FMT_UVC:		descr = "UVC payload header metadata"; break;
 
 	default:
 		/* Compressed formats */
diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h
index 3b08186..c503dcc 100644
--- a/include/uapi/linux/uvcvideo.h
+++ b/include/uapi/linux/uvcvideo.h
@@ -67,4 +67,23 @@ struct uvc_xu_control_query {
 #define UVCIOC_CTRL_MAP		_IOWR('u', 0x20, struct uvc_xu_control_mapping)
 #define UVCIOC_CTRL_QUERY	_IOWR('u', 0x21, struct uvc_xu_control_query)
 
+/*
+ * Metadata node
+ */
+
+/*
+ * UVC metadata nodes fill buffers with possibly multiple instances of the
+ * following struct. The first two fields are added by the driver, they can be
+ * used for clock synchronisation. The rest is an exact copy of a UVC payload
+ * header. Only complete objects with complete buffers are included. Therefore
+ * it's always sizeof(meta->ts) + sizeof(meta->sof) + meta->length bytes large.
+ */
+struct uvc_meta_buf {
+	struct timespec ts;
+	__u16 sof;
+	__u8 length;
+	__u8 flags;
+	__u8 buf[];
+};
+
 #endif
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 45cf735..9b0cc7e 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -683,6 +683,9 @@ struct v4l2_pix_format {
 #define V4L2_META_FMT_VSP1_HGO    v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car VSP1 1-D Histogram */
 #define V4L2_META_FMT_VSP1_HGT    v4l2_fourcc('V', 'S', 'P', 'T') /* R-Car VSP1 2-D Histogram */
 
+/* Meta-data formats */
+#define V4L2_META_FMT_UVC         v4l2_fourcc('U', 'V', 'C', 'H') /* UVC Payload Header metadata */
+
 /* priv field value to indicates that subsequent fields are valid. */
 #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe
 
-- 
1.9.3