[v10,3/6] media: uvcvideo: Quirk for invalid dev_sof in Logitech C922

Message ID 20240323-resend-hwtimestamp-v10-3-b08e590d97c7@chromium.org (mailing list archive)
State New
Delegated to: Laurent Pinchart
Headers
Series uvcvideo: Fixes for hw timestamping |

Commit Message

Ricardo Ribalda March 23, 2024, 10:48 a.m. UTC
  Logitech C922 internal SOF does not increases at a stable rate of 1kHz.
This causes that the device_sof and the host_sof run at different rates,
breaking the clock domain conversion algorithm. Eg:

30 (6) [-] none 30 614400 B 21.245557 21.395214 34.133 fps ts mono/SoE
31 (7) [-] none 31 614400 B 21.275327 21.427246 33.591 fps ts mono/SoE
32 (0) [-] none 32 614400 B 21.304739 21.459256 34.000 fps ts mono/SoE
33 (1) [-] none 33 614400 B 21.334324 21.495274 33.801 fps ts mono/SoE
* 34 (2) [-] none 34 614400 B 21.529237 21.527297 5.130 fps ts mono/SoE
* 35 (3) [-] none 35 614400 B 21.649416 21.559306 8.321 fps ts mono/SoE
36 (4) [-] none 36 614400 B 21.678789 21.595320 34.045 fps ts mono/SoE
...
99 (3) [-] none 99 614400 B 23.542226 23.696352 33.541 fps ts mono/SoE
100 (4) [-] none 100 614400 B 23.571578 23.728404 34.069 fps ts mono/SoE
101 (5) [-] none 101 614400 B 23.601425 23.760420 33.504 fps ts mono/SoE
* 102 (6) [-] none 102 614400 B 23.798324 23.796428 5.079 fps ts mono/SoE
* 103 (7) [-] none 103 614400 B 23.916271 23.828450 8.478 fps ts mono/SoE
104 (0) [-] none 104 614400 B 23.945720 23.860479 33.957 fps ts mono/SoE

Instead of disabling completely the hardware timestamping for such
hardware we take the assumption that the packet handling jitter is
under 2ms and use the host_sof as dev_sof.

We can think of the UVC hardware clock as a system with a coarse clock
(the SOF) and a fine clock (the PTS). The coarse clock can be replaced
with a clock on the same frequency, if the jitter of such clock is
smaller than its sampling rate. That way we can save some of the
precision of the fine clock.

To probe this point we have run three experiments on the Logitech C922.
On that experiment we run the camera at 33fps and we analyse the
difference in msec between a frame and its predecessor. If we display
the histogram of that value, a thinner histogram will mean a better
meassurement. The results for:
- original hw timestamp: https://ibb.co/D1HJJ4x
- pure software timestamp: https://ibb.co/QC9MgVK
- modified hw timestamp: https://ibb.co/8s9dBdk

This bug in the camera firmware has been confirmed by the vendor.

lsusb -v

Bus 001 Device 044: ID 046d:085c Logitech, Inc. C922 Pro Stream Webcam
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x046d Logitech, Inc.
  idProduct          0x085c C922 Pro Stream Webcam
  bcdDevice            0.16
  iManufacturer           0
  iProduct                2 C922 Pro Stream Webcam
  iSerial                 1 80B912DF
  bNumConfigurations      1

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c |  9 +++++++++
 drivers/media/usb/uvc/uvc_video.c  | 11 +++++++++++
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 3 files changed, 21 insertions(+)
  

Comments

Oleksandr Natalenko March 23, 2024, 12:16 p.m. UTC | #1
Hello.

On sobota 23. března 2024 11:48:04, CET Ricardo Ribalda wrote:
> Logitech C922 internal SOF does not increases at a stable rate of 1kHz.
> This causes that the device_sof and the host_sof run at different rates,
> breaking the clock domain conversion algorithm. Eg:
> 
> 30 (6) [-] none 30 614400 B 21.245557 21.395214 34.133 fps ts mono/SoE
> 31 (7) [-] none 31 614400 B 21.275327 21.427246 33.591 fps ts mono/SoE
> 32 (0) [-] none 32 614400 B 21.304739 21.459256 34.000 fps ts mono/SoE
> 33 (1) [-] none 33 614400 B 21.334324 21.495274 33.801 fps ts mono/SoE
> * 34 (2) [-] none 34 614400 B 21.529237 21.527297 5.130 fps ts mono/SoE
> * 35 (3) [-] none 35 614400 B 21.649416 21.559306 8.321 fps ts mono/SoE
> 36 (4) [-] none 36 614400 B 21.678789 21.595320 34.045 fps ts mono/SoE
> ...
> 99 (3) [-] none 99 614400 B 23.542226 23.696352 33.541 fps ts mono/SoE
> 100 (4) [-] none 100 614400 B 23.571578 23.728404 34.069 fps ts mono/SoE
> 101 (5) [-] none 101 614400 B 23.601425 23.760420 33.504 fps ts mono/SoE
> * 102 (6) [-] none 102 614400 B 23.798324 23.796428 5.079 fps ts mono/SoE
> * 103 (7) [-] none 103 614400 B 23.916271 23.828450 8.478 fps ts mono/SoE
> 104 (0) [-] none 104 614400 B 23.945720 23.860479 33.957 fps ts mono/SoE

How do I check whether C920 (046d:082d) is affected too? I have got one, I can run tests on it as long as those will not blow the webcam up.

Thanks.

> Instead of disabling completely the hardware timestamping for such
> hardware we take the assumption that the packet handling jitter is
> under 2ms and use the host_sof as dev_sof.
> 
> We can think of the UVC hardware clock as a system with a coarse clock
> (the SOF) and a fine clock (the PTS). The coarse clock can be replaced
> with a clock on the same frequency, if the jitter of such clock is
> smaller than its sampling rate. That way we can save some of the
> precision of the fine clock.
> 
> To probe this point we have run three experiments on the Logitech C922.
> On that experiment we run the camera at 33fps and we analyse the
> difference in msec between a frame and its predecessor. If we display
> the histogram of that value, a thinner histogram will mean a better
> meassurement. The results for:
> - original hw timestamp: https://ibb.co/D1HJJ4x
> - pure software timestamp: https://ibb.co/QC9MgVK
> - modified hw timestamp: https://ibb.co/8s9dBdk
> 
> This bug in the camera firmware has been confirmed by the vendor.
> 
> lsusb -v
> 
> Bus 001 Device 044: ID 046d:085c Logitech, Inc. C922 Pro Stream Webcam
> Device Descriptor:
>   bLength                18
>   bDescriptorType         1
>   bcdUSB               2.00
>   bDeviceClass          239 Miscellaneous Device
>   bDeviceSubClass         2
>   bDeviceProtocol         1 Interface Association
>   bMaxPacketSize0        64
>   idVendor           0x046d Logitech, Inc.
>   idProduct          0x085c C922 Pro Stream Webcam
>   bcdDevice            0.16
>   iManufacturer           0
>   iProduct                2 C922 Pro Stream Webcam
>   iSerial                 1 80B912DF
>   bNumConfigurations      1
> 
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_driver.c |  9 +++++++++
>  drivers/media/usb/uvc/uvc_video.c  | 11 +++++++++++
>  drivers/media/usb/uvc/uvcvideo.h   |  1 +
>  3 files changed, 21 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index bbd90123a4e76..723e6d5680c2e 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2574,6 +2574,15 @@ static const struct usb_device_id uvc_ids[] = {
>  	  .bInterfaceSubClass	= 1,
>  	  .bInterfaceProtocol	= 0,
>  	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT) },
> +	/* Logitech HD Pro Webcam C922 */
> +	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
> +				| USB_DEVICE_ID_MATCH_INT_INFO,
> +	  .idVendor		= 0x046d,
> +	  .idProduct		= 0x085c,
> +	  .bInterfaceClass	= USB_CLASS_VIDEO,
> +	  .bInterfaceSubClass	= 1,
> +	  .bInterfaceProtocol	= 0,
> +	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_INVALID_DEVICE_SOF) },
>  	/* Chicony CNF7129 (Asus EEE 100HE) */
>  	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
>  				| USB_DEVICE_ID_MATCH_INT_INFO,
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index b2e70fcf4eb4c..d6ca383f643e3 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -558,6 +558,17 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
>  	stream->clock.last_sof = dev_sof;
>  
>  	host_sof = usb_get_current_frame_number(stream->dev->udev);
> +
> +	/*
> +	 * On some devices, like the Logitech C922, the device SOF does not run
> +	 * at a stable rate of 1kHz. For those devices use the host SOF instead.
> +	 * In the tests performed so far, this improves the timestamp precision.
> +	 * This is probably explained by a small packet handling jitter from the
> +	 * host, but the exact reason hasn't been fully determined.
> +	 */
> +	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
> +		dev_sof = host_sof;
> +
>  	time = uvc_video_get_time();
>  
>  	/*
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 6fb0a78b1b009..cb9dd50bba8ac 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -73,6 +73,7 @@
>  #define UVC_QUIRK_FORCE_Y8		0x00000800
>  #define UVC_QUIRK_FORCE_BPP		0x00001000
>  #define UVC_QUIRK_WAKE_AUTOSUSPEND	0x00002000
> +#define UVC_QUIRK_INVALID_DEVICE_SOF	0x00004000
>  
>  /* Format flags */
>  #define UVC_FMT_FLAG_COMPRESSED		0x00000001
> 
>
  
Ricardo Ribalda March 25, 2024, 7:52 a.m. UTC | #2
Hi Oleksandr

On Sat, 23 Mar 2024 at 13:16, Oleksandr Natalenko
<oleksandr@natalenko.name> wrote:

>
> How do I check whether C920 (046d:082d) is affected too? I have got one, I can run tests on it as long as those will not blow the webcam up.
>
> Thanks.
>

First of all you need to enable the hwtimestamps in the driver. You
could do that with

```
rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1
```

Then capture some frames with yavta
```
yavta -c /dev/video0
```

After around 5 seconds all the frames should have a stable fps, the
fps is not stable then your camera is affected with this bug.


Thanks!
  
Oleksandr Natalenko March 25, 2024, 9:23 a.m. UTC | #3
Hello.

On pondělí 25. března 2024 8:52:57, CET Ricardo Ribalda wrote:
> Hi Oleksandr
> 
> On Sat, 23 Mar 2024 at 13:16, Oleksandr Natalenko
> <oleksandr@natalenko.name> wrote:
> 
> >
> > How do I check whether C920 (046d:082d) is affected too? I have got one, I can run tests on it as long as those will not blow the webcam up.
> >
> > Thanks.
> >
> 
> First of all you need to enable the hwtimestamps in the driver. You
> could do that with
> 
> ```
> rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1
> ```

```
$ cat /sys/module/uvcvideo/parameters/hwtimestamps
1
```

> Then capture some frames with yavta
> ```
> yavta -c /dev/video0
> ```
> 
> After around 5 seconds all the frames should have a stable fps, the
> fps is not stable then your camera is affected with this bug.

```
$ ./yavta -c /dev/video1
Device /dev/video1 opened.
Device `HD Pro Webcam C920' on `usb-0000:0f:00.3-3.4' (driver 'uvcvideo') supports video, capture, without mplanes.
Video format: MJPEG (47504a4d) 1920x1080 (stride 0) field none buffer size 4147200
…
100 (4) [-] none 100 200717 B 212.919114 213.079004 33.727 fps ts mono/SoE
101 (5) [-] none 101 200889 B 213.003703 213.114996 11.822 fps ts mono/SoE
102 (6) [-] none 102 200926 B 213.035571 213.146999 31.379 fps ts mono/SoE
103 (7) [-] none 103 200839 B 213.067424 213.179003 31.394 fps ts mono/SoE
104 (0) [-] none 104 200692 B 213.293180 213.214991 4.430 fps ts mono/SoE
105 (1) [-] none 105 200937 B 213.322374 213.247001 34.254 fps ts mono/SoE
106 (2) [-] none 106 201013 B 213.352228 213.279005 33.496 fps ts mono/SoE
…
168 (0) [-] none 168 200914 B 215.183707 215.347066 33.676 fps ts mono/SoE
169 (1) [-] none 169 201141 B 215.271693 215.379066 11.365 fps ts mono/SoE
170 (2) [-] none 170 201005 B 215.303449 215.415057 31.490 fps ts mono/SoE
171 (3) [-] none 171 201195 B 215.335295 215.447062 31.401 fps ts mono/SoE
172 (4) [-] none 172 200933 B 215.557731 215.479072 4.496 fps ts mono/SoE
173 (5) [-] none 173 200973 B 215.587033 215.515063 34.127 fps ts mono/SoE
174 (6) [-] none 174 200698 B 215.616811 215.547063 33.582 fps ts mono/SoE
175 (7) [-] none 175 201290 B 215.646196 215.579075 34.031 fps ts mono/SoE
176 (0) [-] none 176 200807 B 215.675857 215.615073 33.714 fps ts mono/SoE
…
```

Does the above mean the webcam is affected?

Thank you.

> 
> 
> Thanks!
>
  
Ricardo Ribalda March 25, 2024, 9:25 a.m. UTC | #4
Hi Oleksandr

On Mon, 25 Mar 2024 at 10:23, Oleksandr Natalenko
<oleksandr@natalenko.name> wrote:
>
> Hello.
>
> On pondělí 25. března 2024 8:52:57, CET Ricardo Ribalda wrote:
> > Hi Oleksandr
> >
> > On Sat, 23 Mar 2024 at 13:16, Oleksandr Natalenko
> > <oleksandr@natalenko.name> wrote:
> >
> > >
> > > How do I check whether C920 (046d:082d) is affected too? I have got one, I can run tests on it as long as those will not blow the webcam up.
> > >
> > > Thanks.
> > >
> >
> > First of all you need to enable the hwtimestamps in the driver. You
> > could do that with
> >
> > ```
> > rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1
> > ```
>
> ```
> $ cat /sys/module/uvcvideo/parameters/hwtimestamps
> 1
> ```
>
> > Then capture some frames with yavta
> > ```
> > yavta -c /dev/video0
> > ```
> >
> > After around 5 seconds all the frames should have a stable fps, the
> > fps is not stable then your camera is affected with this bug.
>
> ```
> $ ./yavta -c /dev/video1
> Device /dev/video1 opened.
> Device `HD Pro Webcam C920' on `usb-0000:0f:00.3-3.4' (driver 'uvcvideo') supports video, capture, without mplanes.
> Video format: MJPEG (47504a4d) 1920x1080 (stride 0) field none buffer size 4147200
> …
> 100 (4) [-] none 100 200717 B 212.919114 213.079004 33.727 fps ts mono/SoE
> 101 (5) [-] none 101 200889 B 213.003703 213.114996 11.822 fps ts mono/SoE
> 102 (6) [-] none 102 200926 B 213.035571 213.146999 31.379 fps ts mono/SoE
> 103 (7) [-] none 103 200839 B 213.067424 213.179003 31.394 fps ts mono/SoE
> 104 (0) [-] none 104 200692 B 213.293180 213.214991 4.430 fps ts mono/SoE
> 105 (1) [-] none 105 200937 B 213.322374 213.247001 34.254 fps ts mono/SoE
> 106 (2) [-] none 106 201013 B 213.352228 213.279005 33.496 fps ts mono/SoE
> …
> 168 (0) [-] none 168 200914 B 215.183707 215.347066 33.676 fps ts mono/SoE
> 169 (1) [-] none 169 201141 B 215.271693 215.379066 11.365 fps ts mono/SoE
> 170 (2) [-] none 170 201005 B 215.303449 215.415057 31.490 fps ts mono/SoE
> 171 (3) [-] none 171 201195 B 215.335295 215.447062 31.401 fps ts mono/SoE
> 172 (4) [-] none 172 200933 B 215.557731 215.479072 4.496 fps ts mono/SoE
> 173 (5) [-] none 173 200973 B 215.587033 215.515063 34.127 fps ts mono/SoE
> 174 (6) [-] none 174 200698 B 215.616811 215.547063 33.582 fps ts mono/SoE
> 175 (7) [-] none 175 201290 B 215.646196 215.579075 34.031 fps ts mono/SoE
> 176 (0) [-] none 176 200807 B 215.675857 215.615073 33.714 fps ts mono/SoE
> …
> ```
>
> Does the above mean the webcam is affected?

Looks like it.... could you try applying this patch and run with

rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1 quirks=0x4000

to see if that fixes it for you?

Thanks!

>
> Thank you.
>
> >
> >
> > Thanks!
> >
>
>
> --
> Oleksandr Natalenko (post-factum)
  
Oleksandr Natalenko March 25, 2024, 12:50 p.m. UTC | #5
On pondělí 25. března 2024 10:25:51, CET Ricardo Ribalda wrote:
> Hi Oleksandr
> 
> On Mon, 25 Mar 2024 at 10:23, Oleksandr Natalenko
> <oleksandr@natalenko.name> wrote:
> >
> > Hello.
> >
> > On pondělí 25. března 2024 8:52:57, CET Ricardo Ribalda wrote:
> > > Hi Oleksandr
> > >
> > > On Sat, 23 Mar 2024 at 13:16, Oleksandr Natalenko
> > > <oleksandr@natalenko.name> wrote:
> > >
> > > >
> > > > How do I check whether C920 (046d:082d) is affected too? I have got one, I can run tests on it as long as those will not blow the webcam up.
> > > >
> > > > Thanks.
> > > >
> > >
> > > First of all you need to enable the hwtimestamps in the driver. You
> > > could do that with
> > >
> > > ```
> > > rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1
> > > ```
> >
> > ```
> > $ cat /sys/module/uvcvideo/parameters/hwtimestamps
> > 1
> > ```
> >
> > > Then capture some frames with yavta
> > > ```
> > > yavta -c /dev/video0
> > > ```
> > >
> > > After around 5 seconds all the frames should have a stable fps, the
> > > fps is not stable then your camera is affected with this bug.
> >
> > ```
> > $ ./yavta -c /dev/video1
> > Device /dev/video1 opened.
> > Device `HD Pro Webcam C920' on `usb-0000:0f:00.3-3.4' (driver 'uvcvideo') supports video, capture, without mplanes.
> > Video format: MJPEG (47504a4d) 1920x1080 (stride 0) field none buffer size 4147200
> > …
> > 100 (4) [-] none 100 200717 B 212.919114 213.079004 33.727 fps ts mono/SoE
> > 101 (5) [-] none 101 200889 B 213.003703 213.114996 11.822 fps ts mono/SoE
> > 102 (6) [-] none 102 200926 B 213.035571 213.146999 31.379 fps ts mono/SoE
> > 103 (7) [-] none 103 200839 B 213.067424 213.179003 31.394 fps ts mono/SoE
> > 104 (0) [-] none 104 200692 B 213.293180 213.214991 4.430 fps ts mono/SoE
> > 105 (1) [-] none 105 200937 B 213.322374 213.247001 34.254 fps ts mono/SoE
> > 106 (2) [-] none 106 201013 B 213.352228 213.279005 33.496 fps ts mono/SoE
> > …
> > 168 (0) [-] none 168 200914 B 215.183707 215.347066 33.676 fps ts mono/SoE
> > 169 (1) [-] none 169 201141 B 215.271693 215.379066 11.365 fps ts mono/SoE
> > 170 (2) [-] none 170 201005 B 215.303449 215.415057 31.490 fps ts mono/SoE
> > 171 (3) [-] none 171 201195 B 215.335295 215.447062 31.401 fps ts mono/SoE
> > 172 (4) [-] none 172 200933 B 215.557731 215.479072 4.496 fps ts mono/SoE
> > 173 (5) [-] none 173 200973 B 215.587033 215.515063 34.127 fps ts mono/SoE
> > 174 (6) [-] none 174 200698 B 215.616811 215.547063 33.582 fps ts mono/SoE
> > 175 (7) [-] none 175 201290 B 215.646196 215.579075 34.031 fps ts mono/SoE
> > 176 (0) [-] none 176 200807 B 215.675857 215.615073 33.714 fps ts mono/SoE
> > …
> > ```
> >
> > Does the above mean the webcam is affected?
> 
> Looks like it.... could you try applying this patch and run with
> 
> rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1 quirks=0x4000
> 
> to see if that fixes it for you?

On top of v6.8, I've applied the whole v10, and also applied the following change instead of providing `quirks=`:

```
commit 884a61751d979ee9974c08a71c72e88e73bdd87e
Author: Oleksandr Natalenko <oleksandr@natalenko.name>
Date:   Mon Mar 25 10:28:00 2024 +0100

    media: uvcvideo: Quirk for invalid dev_sof in Logitech C920
    
    Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 723e6d5680c2e..444d7089885ea 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2573,7 +2573,8 @@ static const struct usb_device_id uvc_ids[] = {
 	  .bInterfaceClass	= USB_CLASS_VIDEO,
 	  .bInterfaceSubClass	= 1,
 	  .bInterfaceProtocol	= 0,
-	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT) },
+	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT
+					       | UVC_QUIRK_INVALID_DEVICE_SOF) },
 	/* Logitech HD Pro Webcam C922 */
 	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
 				| USB_DEVICE_ID_MATCH_INT_INFO,

```

Now I see this:

```
154 (2) [-] none 154 192417 B 42.199823 42.207788 27.779 fps ts mono/SoE
155 (3) [-] none 155 192040 B 42.231834 42.239791 31.239 fps ts mono/SoE
156 (4) [-] none 156 192213 B 42.263823 42.271822 31.261 fps ts mono/SoE
157 (5) [-] none 157 191981 B 42.299824 42.303827 27.777 fps ts mono/SoE
158 (6) [-] none 158 191953 B 42.331835 42.339811 31.239 fps ts mono/SoE
159 (7) [-] none 159 191904 B 42.363824 42.371813 31.261 fps ts mono/SoE
160 (0) [-] none 160 192210 B 42.399834 42.407801 27.770 fps ts mono/SoE
161 (1) [-] none 161 192235 B 42.431824 42.439806 31.260 fps ts mono/SoE
```

without dips in FPS.

What do you think?

> 
> Thanks!
> 
> >
> > Thank you.
> >
> > >
> > >
> > > Thanks!
> > >
> >
> >
> > --
> > Oleksandr Natalenko (post-factum)
> 
> 
> 
>
  
Ricardo Ribalda March 25, 2024, 2:13 p.m. UTC | #6
Hi Oleksandr

That looks good :) !

On Mon, 25 Mar 2024 at 13:51, Oleksandr Natalenko
<oleksandr@natalenko.name> wrote:
>
> On pondělí 25. března 2024 10:25:51, CET Ricardo Ribalda wrote:
> > Hi Oleksandr
> >
> > On Mon, 25 Mar 2024 at 10:23, Oleksandr Natalenko
> > <oleksandr@natalenko.name> wrote:
> > >
> > > Hello.
> > >
> > > On pondělí 25. března 2024 8:52:57, CET Ricardo Ribalda wrote:
> > > > Hi Oleksandr
> > > >
> > > > On Sat, 23 Mar 2024 at 13:16, Oleksandr Natalenko
> > > > <oleksandr@natalenko.name> wrote:
> > > >
> > > > >
> > > > > How do I check whether C920 (046d:082d) is affected too? I have got one, I can run tests on it as long as those will not blow the webcam up.
> > > > >
> > > > > Thanks.
> > > > >
> > > >
> > > > First of all you need to enable the hwtimestamps in the driver. You
> > > > could do that with
> > > >
> > > > ```
> > > > rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1
> > > > ```
> > >
> > > ```
> > > $ cat /sys/module/uvcvideo/parameters/hwtimestamps
> > > 1
> > > ```
> > >
> > > > Then capture some frames with yavta
> > > > ```
> > > > yavta -c /dev/video0
> > > > ```
> > > >
> > > > After around 5 seconds all the frames should have a stable fps, the
> > > > fps is not stable then your camera is affected with this bug.
> > >
> > > ```
> > > $ ./yavta -c /dev/video1
> > > Device /dev/video1 opened.
> > > Device `HD Pro Webcam C920' on `usb-0000:0f:00.3-3.4' (driver 'uvcvideo') supports video, capture, without mplanes.
> > > Video format: MJPEG (47504a4d) 1920x1080 (stride 0) field none buffer size 4147200
> > > …
> > > 100 (4) [-] none 100 200717 B 212.919114 213.079004 33.727 fps ts mono/SoE
> > > 101 (5) [-] none 101 200889 B 213.003703 213.114996 11.822 fps ts mono/SoE
> > > 102 (6) [-] none 102 200926 B 213.035571 213.146999 31.379 fps ts mono/SoE
> > > 103 (7) [-] none 103 200839 B 213.067424 213.179003 31.394 fps ts mono/SoE
> > > 104 (0) [-] none 104 200692 B 213.293180 213.214991 4.430 fps ts mono/SoE
> > > 105 (1) [-] none 105 200937 B 213.322374 213.247001 34.254 fps ts mono/SoE
> > > 106 (2) [-] none 106 201013 B 213.352228 213.279005 33.496 fps ts mono/SoE
> > > …
> > > 168 (0) [-] none 168 200914 B 215.183707 215.347066 33.676 fps ts mono/SoE
> > > 169 (1) [-] none 169 201141 B 215.271693 215.379066 11.365 fps ts mono/SoE
> > > 170 (2) [-] none 170 201005 B 215.303449 215.415057 31.490 fps ts mono/SoE
> > > 171 (3) [-] none 171 201195 B 215.335295 215.447062 31.401 fps ts mono/SoE
> > > 172 (4) [-] none 172 200933 B 215.557731 215.479072 4.496 fps ts mono/SoE
> > > 173 (5) [-] none 173 200973 B 215.587033 215.515063 34.127 fps ts mono/SoE
> > > 174 (6) [-] none 174 200698 B 215.616811 215.547063 33.582 fps ts mono/SoE
> > > 175 (7) [-] none 175 201290 B 215.646196 215.579075 34.031 fps ts mono/SoE
> > > 176 (0) [-] none 176 200807 B 215.675857 215.615073 33.714 fps ts mono/SoE
> > > …
> > > ```
> > >
> > > Does the above mean the webcam is affected?
> >
> > Looks like it.... could you try applying this patch and run with
> >
> > rmmod uvcvideo; modprobe uvcvideo hwtimestamps=1 quirks=0x4000
> >
> > to see if that fixes it for you?
>
> On top of v6.8, I've applied the whole v10, and also applied the following change instead of providing `quirks=`:

Could you send the patch to the ML, so Laurent can apply it on top of my set?

You could add the result of the experiment to the commit message

With those changes

Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>

Thanks!

>
> ```
> commit 884a61751d979ee9974c08a71c72e88e73bdd87e
> Author: Oleksandr Natalenko <oleksandr@natalenko.name>
> Date:   Mon Mar 25 10:28:00 2024 +0100
>
>     media: uvcvideo: Quirk for invalid dev_sof in Logitech C920
>
>     Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
>
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 723e6d5680c2e..444d7089885ea 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2573,7 +2573,8 @@ static const struct usb_device_id uvc_ids[] = {
>           .bInterfaceClass      = USB_CLASS_VIDEO,
>           .bInterfaceSubClass   = 1,
>           .bInterfaceProtocol   = 0,
> -         .driver_info          = UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT) },
> +         .driver_info          = UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT
> +                                              | UVC_QUIRK_INVALID_DEVICE_SOF) },
>         /* Logitech HD Pro Webcam C922 */
>         { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
>                                 | USB_DEVICE_ID_MATCH_INT_INFO,
>
> ```
>
> Now I see this:
>
> ```
> 154 (2) [-] none 154 192417 B 42.199823 42.207788 27.779 fps ts mono/SoE
> 155 (3) [-] none 155 192040 B 42.231834 42.239791 31.239 fps ts mono/SoE
> 156 (4) [-] none 156 192213 B 42.263823 42.271822 31.261 fps ts mono/SoE
> 157 (5) [-] none 157 191981 B 42.299824 42.303827 27.777 fps ts mono/SoE
> 158 (6) [-] none 158 191953 B 42.331835 42.339811 31.239 fps ts mono/SoE
> 159 (7) [-] none 159 191904 B 42.363824 42.371813 31.261 fps ts mono/SoE
> 160 (0) [-] none 160 192210 B 42.399834 42.407801 27.770 fps ts mono/SoE
> 161 (1) [-] none 161 192235 B 42.431824 42.439806 31.260 fps ts mono/SoE
> ```
>
> without dips in FPS.
>
> What do you think?
>
> >
> > Thanks!
> >
> > >
> > > Thank you.
> > >
> > > >
> > > >
> > > > Thanks!
> > > >
> > >
> > >
> > > --
> > > Oleksandr Natalenko (post-factum)
> >
> >
> >
> >
>
>
> --
> Oleksandr Natalenko (post-factum)
  
Tomasz Figa May 29, 2024, 7:20 a.m. UTC | #7
On Sat, Mar 23, 2024 at 10:48:04AM +0000, Ricardo Ribalda wrote:
> Logitech C922 internal SOF does not increases at a stable rate of 1kHz.
> This causes that the device_sof and the host_sof run at different rates,
> breaking the clock domain conversion algorithm. Eg:
> 
> 30 (6) [-] none 30 614400 B 21.245557 21.395214 34.133 fps ts mono/SoE
> 31 (7) [-] none 31 614400 B 21.275327 21.427246 33.591 fps ts mono/SoE
> 32 (0) [-] none 32 614400 B 21.304739 21.459256 34.000 fps ts mono/SoE
> 33 (1) [-] none 33 614400 B 21.334324 21.495274 33.801 fps ts mono/SoE
> * 34 (2) [-] none 34 614400 B 21.529237 21.527297 5.130 fps ts mono/SoE
> * 35 (3) [-] none 35 614400 B 21.649416 21.559306 8.321 fps ts mono/SoE
> 36 (4) [-] none 36 614400 B 21.678789 21.595320 34.045 fps ts mono/SoE
> ...
> 99 (3) [-] none 99 614400 B 23.542226 23.696352 33.541 fps ts mono/SoE
> 100 (4) [-] none 100 614400 B 23.571578 23.728404 34.069 fps ts mono/SoE
> 101 (5) [-] none 101 614400 B 23.601425 23.760420 33.504 fps ts mono/SoE
> * 102 (6) [-] none 102 614400 B 23.798324 23.796428 5.079 fps ts mono/SoE
> * 103 (7) [-] none 103 614400 B 23.916271 23.828450 8.478 fps ts mono/SoE
> 104 (0) [-] none 104 614400 B 23.945720 23.860479 33.957 fps ts mono/SoE
> 
> Instead of disabling completely the hardware timestamping for such
> hardware we take the assumption that the packet handling jitter is
> under 2ms and use the host_sof as dev_sof.
> 
> We can think of the UVC hardware clock as a system with a coarse clock
> (the SOF) and a fine clock (the PTS). The coarse clock can be replaced
> with a clock on the same frequency, if the jitter of such clock is
> smaller than its sampling rate. That way we can save some of the
> precision of the fine clock.
> 
> To probe this point we have run three experiments on the Logitech C922.
> On that experiment we run the camera at 33fps and we analyse the
> difference in msec between a frame and its predecessor. If we display
> the histogram of that value, a thinner histogram will mean a better
> meassurement. The results for:
> - original hw timestamp: https://ibb.co/D1HJJ4x
> - pure software timestamp: https://ibb.co/QC9MgVK
> - modified hw timestamp: https://ibb.co/8s9dBdk
> 
> This bug in the camera firmware has been confirmed by the vendor.
> 
> lsusb -v
> 
> Bus 001 Device 044: ID 046d:085c Logitech, Inc. C922 Pro Stream Webcam
> Device Descriptor:
>   bLength                18
>   bDescriptorType         1
>   bcdUSB               2.00
>   bDeviceClass          239 Miscellaneous Device
>   bDeviceSubClass         2
>   bDeviceProtocol         1 Interface Association
>   bMaxPacketSize0        64
>   idVendor           0x046d Logitech, Inc.
>   idProduct          0x085c C922 Pro Stream Webcam
>   bcdDevice            0.16
>   iManufacturer           0
>   iProduct                2 C922 Pro Stream Webcam
>   iSerial                 1 80B912DF
>   bNumConfigurations      1
> 
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_driver.c |  9 +++++++++
>  drivers/media/usb/uvc/uvc_video.c  | 11 +++++++++++
>  drivers/media/usb/uvc/uvcvideo.h   |  1 +
>  3 files changed, 21 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index bbd90123a4e76..723e6d5680c2e 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2574,6 +2574,15 @@ static const struct usb_device_id uvc_ids[] = {
>  	  .bInterfaceSubClass	= 1,
>  	  .bInterfaceProtocol	= 0,
>  	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT) },
> +	/* Logitech HD Pro Webcam C922 */
> +	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
> +				| USB_DEVICE_ID_MATCH_INT_INFO,
> +	  .idVendor		= 0x046d,
> +	  .idProduct		= 0x085c,
> +	  .bInterfaceClass	= USB_CLASS_VIDEO,
> +	  .bInterfaceSubClass	= 1,
> +	  .bInterfaceProtocol	= 0,
> +	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_INVALID_DEVICE_SOF) },
>  	/* Chicony CNF7129 (Asus EEE 100HE) */
>  	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
>  				| USB_DEVICE_ID_MATCH_INT_INFO,
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index b2e70fcf4eb4c..d6ca383f643e3 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -558,6 +558,17 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
>  	stream->clock.last_sof = dev_sof;
>  
>  	host_sof = usb_get_current_frame_number(stream->dev->udev);
> +
> +	/*
> +	 * On some devices, like the Logitech C922, the device SOF does not run
> +	 * at a stable rate of 1kHz. For those devices use the host SOF instead.
> +	 * In the tests performed so far, this improves the timestamp precision.
> +	 * This is probably explained by a small packet handling jitter from the
> +	 * host, but the exact reason hasn't been fully determined.

Given that the counter increases at a low frequency (1 kHz), we have a
millisecond from when the frame is received to go into
uvc_video_clock_decode() and read it, which should be quite realistic in
normal conditions.

I suspect that under a relatively high interrupt load, with interrupts
of higher priority than USB host, we could end up with more jitter, but
it should be still better compared to the broken hw timestamp behavior
and not worse than sw timestamp, because that would be subjected to many
more factors introducing jitter.

Reviewed-by: Tomasz Figa <tfiga@chromium.org>

Best regards,
Tomasz
  

Patch

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index bbd90123a4e76..723e6d5680c2e 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2574,6 +2574,15 @@  static const struct usb_device_id uvc_ids[] = {
 	  .bInterfaceSubClass	= 1,
 	  .bInterfaceProtocol	= 0,
 	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_RESTORE_CTRLS_ON_INIT) },
+	/* Logitech HD Pro Webcam C922 */
+	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
+				| USB_DEVICE_ID_MATCH_INT_INFO,
+	  .idVendor		= 0x046d,
+	  .idProduct		= 0x085c,
+	  .bInterfaceClass	= USB_CLASS_VIDEO,
+	  .bInterfaceSubClass	= 1,
+	  .bInterfaceProtocol	= 0,
+	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_INVALID_DEVICE_SOF) },
 	/* Chicony CNF7129 (Asus EEE 100HE) */
 	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
 				| USB_DEVICE_ID_MATCH_INT_INFO,
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index b2e70fcf4eb4c..d6ca383f643e3 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -558,6 +558,17 @@  uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	stream->clock.last_sof = dev_sof;
 
 	host_sof = usb_get_current_frame_number(stream->dev->udev);
+
+	/*
+	 * On some devices, like the Logitech C922, the device SOF does not run
+	 * at a stable rate of 1kHz. For those devices use the host SOF instead.
+	 * In the tests performed so far, this improves the timestamp precision.
+	 * This is probably explained by a small packet handling jitter from the
+	 * host, but the exact reason hasn't been fully determined.
+	 */
+	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
+		dev_sof = host_sof;
+
 	time = uvc_video_get_time();
 
 	/*
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 6fb0a78b1b009..cb9dd50bba8ac 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -73,6 +73,7 @@ 
 #define UVC_QUIRK_FORCE_Y8		0x00000800
 #define UVC_QUIRK_FORCE_BPP		0x00001000
 #define UVC_QUIRK_WAKE_AUTOSUSPEND	0x00002000
+#define UVC_QUIRK_INVALID_DEVICE_SOF	0x00004000
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001