Re: [RFC 1/2] uvc: Add a quirk flag for cameras that do not produce correct timestamps

Laurent Pinchart
2015-11-09T16:18:12Z

Hi Sakari,

On Wednesday 05 November 2014 18:12:33 Sakari Ailus wrote:
> The UVC devices do produce hardware timestamps according to the spec, but
> not all cameras implement it or implement it correctly. Add a quirk flag for
> such devices, and use monotonic timestamp from the end of the frame
> instead.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

I don't think this is the right fix, as the problem seems to come from the
driver, not from the camera. I've disabled hardware timestamps by default for
now which should work around the problem until I find time to conduct a full
investigation and fix it.

> ---
> drivers/media/usb/uvc/uvc_queue.c | 6 ++++--
> drivers/media/usb/uvc/uvc_video.c | 14 +++++++++++++-
> drivers/media/usb/uvc/uvcvideo.h | 4 +++-
> 3 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_queue.c
> b/drivers/media/usb/uvc/uvc_queue.c index 6e92d20..3f6432f 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -141,7 +141,7 @@ static struct vb2_ops uvc_queue_qops = {
> };
>
> int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
> - int drop_corrupted)
> + bool drop_corrupted, bool tstamp_eof)
> {
> int ret;
>
> @@ -152,7 +152,9 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum
> v4l2_buf_type type, queue->queue.ops = &uvc_queue_qops;
> queue->queue.mem_ops = &vb2_vmalloc_memops;
> queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
> - | V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
> + | (tstamp_eof ? V4L2_BUF_FLAG_TSTAMP_SRC_EOF
> + : V4L2_BUF_FLAG_TSTAMP_SRC_SOE);
> +
> ret = vb2_queue_init(&queue->queue);
> if (ret)
> return ret;
> diff --git a/drivers/media/usb/uvc/uvc_video.c
> b/drivers/media/usb/uvc/uvc_video.c index df81b9c..f599112 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -382,6 +382,9 @@ uvc_video_clock_decode(struct uvc_streaming *stream,
> struct uvc_buffer *buf, u16 host_sof;
> u16 dev_sof;
>
> + if (stream->dev->quirks & UVC_QUIRK_BAD_TIMESTAMP)
> + return;
> +
> switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
> case UVC_STREAM_PTS | UVC_STREAM_SCR:
> header_size = 12;
> @@ -490,6 +493,9 @@ static int uvc_video_clock_init(struct uvc_streaming
> *stream) {
> struct uvc_clock *clock = &stream->clock;
>
> + if (stream->dev->quirks & UVC_QUIRK_BAD_TIMESTAMP)
> + return 0;
> +
> spin_lock_init(&clock->lock);
> clock->size = 32;
>
> @@ -615,6 +621,11 @@ void uvc_video_clock_update(struct uvc_streaming
> *stream, u32 rem;
> u64 y;
>
> + if (stream->dev->quirks & UVC_QUIRK_BAD_TIMESTAMP) {
> + v4l2_get_timestamp(&v4l2_buf->timestamp);
> + return;
> + }
> +
> spin_lock_irqsave(&clock->lock, flags);
>
> if (clock->count < clock->size)
> @@ -1779,7 +1790,8 @@ int uvc_video_init(struct uvc_streaming *stream)
> atomic_set(&stream->active, 0);
>
> /* Initialize the video buffers queue. */
> - ret = uvc_queue_init(&stream->queue, stream->type, !uvc_no_drop_param);
> + ret = uvc_queue_init(&stream->queue, stream->type, !uvc_no_drop_param,
> + stream->dev->quirks & UVC_QUIRK_BAD_TIMESTAMP);
> if (ret)
> return ret;
>
> diff --git a/drivers/media/usb/uvc/uvcvideo.h
> b/drivers/media/usb/uvc/uvcvideo.h index 864ada7..89a638c 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -148,6 +148,7 @@
> #define UVC_QUIRK_PROBE_DEF 0x00000100
> #define UVC_QUIRK_RESTRICT_FRAME_RATE 0x00000200
> #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
> +#define UVC_QUIRK_BAD_TIMESTAMP 0x00000800
>
> /* Format flags */
> #define UVC_FMT_FLAG_COMPRESSED 0x00000001
> @@ -622,7 +623,8 @@ extern struct uvc_entity *uvc_entity_by_id(struct
> uvc_device *dev, int id);
>
> /* Video buffers queue management. */
> extern int uvc_queue_init(struct uvc_video_queue *queue,
> - enum v4l2_buf_type type, int drop_corrupted);
> + enum v4l2_buf_type type, bool drop_corrupted,
> + bool tstamp_eof);
> extern int uvc_alloc_buffers(struct uvc_video_queue *queue,
> struct v4l2_requestbuffers *rb);
> extern void uvc_free_buffers(struct uvc_video_queue *queue);

--
Regards,

Laurent Pinchart