2019-12-25 02:38:39

by Jun Chen

Subject: [PATCH] media: uvcvideo: Fix annotation for uvc_video_clock_update()

From: Jun Chen <[email protected]>

The formula (2) is to convert from SOF to host clock,
it should be fix as
"TS = ((TS2 - TS1) * SOF + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1)"

Signed-off-by: Jun Chen <[email protected]>
---
drivers/media/usb/uvc/uvc_video.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 8fa77a8..a3150da 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -622,7 +622,7 @@ static u16 uvc_video_clock_host_sof(const struct uvc_clock_sample *sample)
* to avoid losing precision in the division. Similarly, the host timestamp is
* computed with
*
- * TS = ((TS2 - TS1) * PTS + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1) (2)
+ * TS = ((TS2 - TS1) * SOF + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1) (2)
*
* SOF values are coded on 11 bits by USB. We extend their precision with 16
* decimal bits, leading to a 11.16 coding.
--
1.9.1

2020-01-01 17:30:08

by Laurent Pinchart

Subject: Re: [PATCH] media: uvcvideo: Fix annotation for uvc_video_clock_update()

Hello Jun,

Thank you for the patch.

On Wed, Dec 25, 2019 at 10:34:17AM +0800, Jun Chen wrote:
> From: Jun Chen <[email protected]>
>
> The formula (2) is to convert from SOF to host clock,
> it should be fix as
> "TS = ((TS2 - TS1) * SOF + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1)"
>
> Signed-off-by: Jun Chen <[email protected]>

Reviewed-by: Laurent Pinchart <[email protected]>

and applied to my tree.

> ---
> drivers/media/usb/uvc/uvc_video.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index 8fa77a8..a3150da 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -622,7 +622,7 @@ static u16 uvc_video_clock_host_sof(const struct uvc_clock_sample *sample)
> * to avoid losing precision in the division. Similarly, the host timestamp is
> * computed with
> *
> - * TS = ((TS2 - TS1) * PTS + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1) (2)
> + * TS = ((TS2 - TS1) * SOF + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1) (2)
> *
> * SOF values are coded on 11 bits by USB. We extend their precision with 16
> * decimal bits, leading to a 11.16 coding.

--
Regards,

Laurent Pinchart