media: uvcvideo: Fix hw timestamp handling for slow FPS

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In UVC 1.5 we get a single clock value per frame. With the current
buffer size of 32, FPS slowers than 32 might roll-over twice.

The current code cannot handle two roll-over and provide invalid
timestamps.

Revome all the samples from the circular buffer that are more than two
rollovers old, so the algorithm always provides good timestamps.

Note that we are removing values that are more than one second old,
which means that there is enough distance between the two points that
we use for the interpolation to provide good values.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20240610-hwtimestamp-followup-v1-1-f9eaed7be7f0@chromium.org
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

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Ricardo Ribalda 2024-06-10 19:17:48 +00:00 • committed by Laurent Pinchart

parent 141270bd95

commit 53d7995383

2 changed files with 23 additions and 0 deletions

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22

drivers/media/usb/uvc/uvc_video.c

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1

drivers/media/usb/uvc/uvcvideo.h

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