linux-kernel - [PATCH v2 4/8] media: uvcvideo: Quirk for invalid dev

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Message-Id: <20220920-resend-hwtimestamp-v2-4-d8d0616bb612@chromium.org>
Date:   Thu, 03 Nov 2022 14:40:45 +0100
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     HungNien Chen <hn.chen@...plusit.com>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH v2 4/8] media: uvcvideo: Quirk for invalid dev_sof in Logi C922

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@...omium.org>

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

-- 
b4 0.11.0-dev-d93f8