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-rw-r--r--drivers/media/usb/uvc/uvc_driver.c9
-rw-r--r--drivers/media/usb/uvc/uvc_video.c11
-rw-r--r--drivers/media/usb/uvc/uvcvideo.h1
3 files changed, 21 insertions, 0 deletions
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 8fe24c98087e..6e55f91ac17f 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2581,6 +2581,15 @@ 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) },
/* Logitech Rally Bar Huddle */
{ .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 b2e70fcf4eb4..d6ca383f643e 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 3653b2c8a86c..e5b12717016f 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -75,6 +75,7 @@
#define UVC_QUIRK_WAKE_AUTOSUSPEND 0x00002000
#define UVC_QUIRK_NO_RESET_RESUME 0x00004000
#define UVC_QUIRK_DISABLE_AUTOSUSPEND 0x00008000
+#define UVC_QUIRK_INVALID_DEVICE_SOF 0x00010000
/* Format flags */
#define UVC_FMT_FLAG_COMPRESSED 0x00000001