[PATCH v2] media: uvcvideo: Quirk for hardware with invalid sof
From: Ricardo Ribalda
Date: Wed Aug 18 2021 - 16:35:09 EST
The hardware timestamping code has the assumption than the device_sof
and the host_sof run at the same frequency (1 KHz).
Unfortunately, this is not the case for all the hardware. Add a quirk to
support such hardware.
Note on how to identify such hardware:
When running with "yavta -c /dev/videoX" Look for periodic jumps of the
fps. 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
They happen because the delta_sof calculated at
uvc_video_clock_host_sof(), wraps periodically, as both clocks drift.
Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
v2: Fix typo in frequency
drivers/media/usb/uvc/uvc_driver.c | 9 +++++++++
drivers/media/usb/uvc/uvc_video.c | 11 +++++++++--
drivers/media/usb/uvc/uvcvideo.h | 2 ++
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 9a791d8ef200..d1e6cba10b15 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2771,6 +2771,15 @@ 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 6d0e474671a2..760ab015cf9c 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -518,13 +518,20 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
/* To limit the amount of data, drop SCRs with an SOF identical to the
* previous one.
*/
- dev_sof = get_unaligned_le16(&data[header_size - 2]);
+ if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
+ dev_sof = usb_get_current_frame_number(stream->dev->udev);
+ else
+ dev_sof = get_unaligned_le16(&data[header_size - 2]);
+
if (dev_sof == stream->clock.last_sof)
return;
stream->clock.last_sof = dev_sof;
- host_sof = usb_get_current_frame_number(stream->dev->udev);
+ if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
+ host_sof = dev_sof;
+ else
+ host_sof = usb_get_current_frame_number(stream->dev->udev);
time = uvc_video_get_time();
/* The UVC specification allows device implementations that can't obtain
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index cce5e38133cd..89d909661915 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -209,6 +209,8 @@
#define UVC_QUIRK_RESTORE_CTRLS_ON_INIT 0x00000400
#define UVC_QUIRK_FORCE_Y8 0x00000800
#define UVC_QUIRK_FORCE_BPP 0x00001000
+#define UVC_QUIRK_INVALID_DEVICE_SOF 0x00002000
+
/* Format flags */
#define UVC_FMT_FLAG_COMPRESSED 0x00000001
--
2.33.0.rc2.250.ged5fa647cd-goog