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 package handling jitter is under 2ms and use the host_sof as dev_sof. For the hardware tested, it provides a much better timestamping than a pure software solution: https://ibb.co/D1HJJ4x https://ibb.co/8s9dBdk https://ibb.co/QC9MgVK 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 Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> --- 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, 19 insertions(+), 2 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index 80ef0f0e04b0..4512316c8748 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -2880,6 +2880,15 @@ 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 a5b184e71ad7..d387d6335344 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -529,13 +529,20 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf, * data packages of the same frame contains the same sof. In that case * only the first one will match the host_sof. */ - 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(); /* diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index f395b67fe95a..e41289605d0e 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -213,6 +213,7 @@ #define UVC_QUIRK_FORCE_Y8 0x00000800 #define UVC_QUIRK_FORCE_BPP 0x00001000 #define UVC_QUIRK_IGNORE_EMPTY_TS 0x00002000 +#define UVC_QUIRK_INVALID_DEVICE_SOF 0x00004000 /* Format flags */ #define UVC_FMT_FLAG_COMPRESSED 0x00000001 -- 2.39.0.rc0.267.gcb52ba06e7-goog-b4-0.11.0-dev-696ae
