[PATCH v3 0/8] [PATCH 0/8] uvcvideo: Fixes for hw timestamping

[PATCH v3 0/8] [PATCH 0/8] uvcvideo: Fixes for hw timestamping

[Ricardo Ribalda]

Add some fixes for fixing hw timestamp on some Logitech and SunplusIT
cameras. The issues have been previously reported to the manufacturers.

Also include a patch to fix the current hw timestamping logic for ANY
uvc 1.5 model running at under 16 fps.

To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-media@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: hn.chen <hn.chen@sunplusit.com>
Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>

---
Changes in v3 (Thanks Laurent!):
- Rebase on top of pinchart/uvc/next
- Fix hw timestampt handling for slow FPS
  - Improve commit message
- Quirk for invalid dev_sof in Logi C922
  - Improve commit message
- Allow hw clock updates with buffers not full
  - Fix typo and improve messages
- Refactor clock circular buffer
  - Improve commit message
- Quirk for autosuspend in Logi C910
  - Improve commit message
  - Add comments around the quirk
- Create UVC_QUIRK_IGNORE_EMPTY_TS quirk
  - Improve comments
- Allow quirking by entity guid
   - unsinged int
- Extend documentation of uvc_video_clock_decode()
   - uvcvideo on commit message
   - Improve comment
- Link to v2: https://lore.kernel.org/r/20220920-resend-hwtimestamp-v2-0-d8d0616bb612@chromium.org

Changes in v2:
- Require 1/4 sec of data before using the hw timestamps
- Add Tested-by SunplusIT
- Link to v1: https://lore.kernel.org/r/20220920-resend-hwtimestamp-v1-0-e9c14b258404@chromium.org

---
Ricardo Ribalda (8):
      media: uvcvideo: Extend documentation of uvc_video_clock_decode()
      media: uvc: Allow quirking by entity guid
      media: uvc: Create UVC_QUIRK_IGNORE_EMPTY_TS quirk
      media: uvcvideo: Quirk for invalid dev_sof in Logitech C922
      media: uvcvideo: Quirk for autosuspend in Logitech B910 and C910
      media: uvcvideo: Allow hw clock updates with buffers not full
      media: uvcvideo: Refactor clock circular buffer
      media: uvcvideo: Fix hw timestamp handling for slow FPS

 drivers/media/usb/uvc/uvc_driver.c |  63 +++++++++++++++++
 drivers/media/usb/uvc/uvc_video.c  | 136 +++++++++++++++++++++++++------------
 drivers/media/usb/uvc/uvcvideo.h   |   4 ++
 3 files changed, 158 insertions(+), 45 deletions(-)
---
base-commit: 58540610e464d8b2ba46a11b81c3e6fcc4118fae
change-id: 20220920-resend-hwtimestamp-b3e22729284d

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>

[PATCH v3 1/8] media: uvcvideo: Extend documentation of uvc_video_clock_decode()

[Ricardo Ribalda]

Make an explicit reference to UVC 1.5, explaining how the algorithm
supports the different behaviour of UVC 1.1 and 1.5.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index d2eb9066e4dc..def079c7a6fd 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -516,7 +516,9 @@ 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.
+	 * previous one. This filtering is also needed to support UVC 1.5, where
+	 * all the data packets 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 (dev_sof == stream->clock.last_sof)

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 2/8] media: uvc: Allow quirking by entity guid

[Ricardo Ribalda]

When an IP is shared by multiple devices its erratas will be shared by
all of them. Instead of creating a long list of device quirks, or
waiting for the users to report errors in their hardware lets add a
routine to add quirks based on the entity guid.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index bd3716a359b0..5448576a8413 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1195,6 +1195,28 @@ static int uvc_parse_control(struct uvc_device *dev)
 	return 0;
 }
 
+static const struct uvc_entity_quirk {
+	u8 guid[16];
+	u32 quirks;
+} uvc_entity_quirk[] = {
+};
+
+static void uvc_entity_quirks(struct uvc_device *dev)
+{
+	struct uvc_entity *entity;
+	unsigned int i;
+
+	list_for_each_entry(entity, &dev->entities, list) {
+		for (i = 0; i < ARRAY_SIZE(uvc_entity_quirk); i++) {
+			if (memcmp(entity->guid, uvc_entity_quirk[i].guid,
+				   sizeof(entity->guid)) == 0) {
+				dev->quirks |= uvc_entity_quirk[i].quirks;
+				break;
+			}
+		}
+	}
+}
+
 /* -----------------------------------------------------------------------------
  * Privacy GPIO
  */
@@ -2154,6 +2176,9 @@ static int uvc_probe(struct usb_interface *intf,
 		goto error;
 	}
 
+	/* Apply entity based quirks */
+	uvc_entity_quirks(dev);
+
 	dev_info(&dev->udev->dev, "Found UVC %u.%02x device %s (%04x:%04x)\n",
 		 dev->uvc_version >> 8, dev->uvc_version & 0xff,
 		 udev->product ? udev->product : "<unnamed>",

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 3/8] media: uvc: Create UVC_QUIRK_IGNORE_EMPTY_TS quirk

[Ricardo Ribalda]

Some SunplusIT cameras took a borderline interpretation of the UVC 1.5
standard, and fill the PTS and SCR fields with invalid data if the
package does not contain data.

"STC must be captured when the first video data of a video frame is put
on the USB bus."

Eg:

buffer: 0xa7755c00 len 000012 header:0x8c stc 00000000 sof 0000 pts 00000000
buffer: 0xa7755c00 len 000012 header:0x8c stc 00000000 sof 0000 pts 00000000
buffer: 0xa7755c00 len 000668 header:0x8c stc 73779dba sof 070c pts 7376d37a

This borderline/buggy interpretation has been implemented in a variety
of devices, from directly SunplusIT and from other OEMs that rebrand
SunplusIT products.

Luckily we can identify the affected modules by looking at the guid of
one of the extension units:

VideoControl Interface Descriptor:
  guidExtensionCode         {82066163-7050-ab49-b8cc-b3855e8d221d}

This patch adds a new quirk to take care of this.

lsusb of one of the affected cameras:

Bus 001 Device 003: ID 1bcf:2a01 Sunplus Innovation Technology Inc.
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.01
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 ?
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x1bcf Sunplus Innovation Technology Inc.
  idProduct          0x2a01
  bcdDevice            0.02
  iManufacturer           1 SunplusIT Inc
  iProduct                2 HanChen Wise Camera
  iSerial                 3 01.00.00
  bNumConfigurations      1

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 11 +++++++++++
 drivers/media/usb/uvc/uvc_video.c  | 10 ++++++++++
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 3 files changed, 22 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 5448576a8413..c5ab6e2d24c3 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1199,6 +1199,17 @@ static const struct uvc_entity_quirk {
 	u8 guid[16];
 	u32 quirks;
 } uvc_entity_quirk[] = {
+	/*
+	 * Some SunPlusIT uvc 1.5 device firmware expects that packages with
+	 * no frame data are ignored by the host. Therefore it does not clear
+	 * the PTS/SCR bits in the header, and breaks the timestamp decode
+	 * algorithm.
+	 */
+	{
+		.guid = {0x82, 0x06, 0x61, 0x63, 0x70, 0x50, 0xab, 0x49,
+			 0xb8, 0xcc, 0xb3, 0x85, 0x5e, 0x8d, 0x22, 0x1d},
+		.quirks = UVC_QUIRK_IGNORE_EMPTY_TS,
+	},
 };
 
 static void uvc_entity_quirks(struct uvc_device *dev)
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index def079c7a6fd..f469c62bedca 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -500,6 +500,16 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	if (len < header_size)
 		return;
 
+	/*
+	 * Some devices make a borderline interpreation of the UVC 1.5 standard
+	 * and the packets with no data contain undefined timestamps. Ignore
+	 * such packages to avoid interfering with the clock interpolation
+	 * algorithm.
+	 */
+	if (stream->dev->quirks & UVC_QUIRK_IGNORE_EMPTY_TS &&
+	    len == header_size)
+		return;
+
 	/*
 	 * Extract the timestamps:
 	 *
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index df93db259312..c3424ae29339 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -74,6 +74,7 @@
 #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT	0x00000400
 #define UVC_QUIRK_FORCE_Y8		0x00000800
 #define UVC_QUIRK_FORCE_BPP		0x00001000
+#define UVC_QUIRK_IGNORE_EMPTY_TS	0x00002000
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 4/8] media: uvcvideo: Quirk for invalid dev_sof in Logitech C922

[Ricardo Ribalda]

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

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, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index c5ab6e2d24c3..c89a1eebe91c 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2582,6 +2582,15 @@ 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 f469c62bedca..bc75c7c40251 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -530,13 +530,20 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * all the data packets 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 c3424ae29339..88d1790e6695 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -75,6 +75,7 @@
 #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

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 5/8] media: uvcvideo: Quirk for autosuspend in Logitech B910 and C910

[Ricardo Ribalda]

Logitech B910 and C910 firmware are unable to recover from an USB
autosuspend. When it resumes, the device is in a state where it only produces
invalid frames. Eg:

$ echo 0xFFFF > /sys/module/uvcvideo/parameters/trace # enable verbose log
$ yavta -c1 -n1 --file='frame#.jpg' --format MJPEG --size=1920x1080 /dev/video1
[350438.435219] uvcvideo: uvc_v4l2_open
[350438.529794] uvcvideo: Resuming interface 2
[350438.529801] uvcvideo: Resuming interface 3
[350438.529991] uvcvideo: Trying format 0x47504a4d (MJPG): 1920x1080.
[350438.529996] uvcvideo: Using default frame interval 33333.3 us (30.0 fps).
[350438.551496] uvcvideo: uvc_v4l2_mmap
[350438.555890] uvcvideo: Device requested 3060 B/frame bandwidth.
[350438.555896] uvcvideo: Selecting alternate setting 11 (3060 B/frame bandwidth).
[350438.556362] uvcvideo: Allocated 5 URB buffers of 32x3060 bytes each.
[350439.316468] uvcvideo: Marking buffer as bad (error bit set).
[350439.316475] uvcvideo: Frame complete (EOF found).
[350439.316477] uvcvideo: EOF in empty payload.
[350439.316484] uvcvideo: frame 1 stats: 149/261/417 packets, 1/149/417 pts (early initial), 416/417 scr, last pts/stc/sof 2976325734/2978107243/249
[350439.384510] uvcvideo: Marking buffer as bad (error bit set).
[350439.384516] uvcvideo: Frame complete (EOF found).
[350439.384518] uvcvideo: EOF in empty payload.
[350439.384525] uvcvideo: frame 2 stats: 265/379/533 packets, 1/265/533 pts (early initial), 532/533 scr, last pts/stc/sof 2979524454/2981305193/316
[350439.448472] uvcvideo: Marking buffer as bad (error bit set).
[350439.448478] uvcvideo: Frame complete (EOF found).
[350439.448480] uvcvideo: EOF in empty payload.
[350439.448487] uvcvideo: frame 3 stats: 265/377/533 packets, 1/265/533 pts (early initial), 532/533 scr, last pts/stc/sof 2982723174/2984503144/382
...(loop)...

The devices can leave this invalid state if the alternate setting of
the streaming interface is toggled.

This patch adds a quirk for this device so it can be autosuspended
properly.

lsusb -v:
Bus 001 Device 049: ID 046d:0821 Logitech, Inc. HD Webcam C910
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          0x0821 HD Webcam C910
  bcdDevice            0.10
  iManufacturer           0
  iProduct                0
  iSerial                 1 390022B0
  bNumConfigurations      1

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 18 ++++++++++++++++++
 drivers/media/usb/uvc/uvc_video.c  | 10 ++++++++++
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 3 files changed, 29 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index c89a1eebe91c..be6ad9b732a2 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2525,6 +2525,24 @@ static const struct usb_device_id uvc_ids[] = {
 	  .bInterfaceSubClass	= 1,
 	  .bInterfaceProtocol	= 0,
 	  .driver_info		= (kernel_ulong_t)&uvc_quirk_probe_minmax },
+	/* Logitech, Webcam C910 */
+	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
+				| USB_DEVICE_ID_MATCH_INT_INFO,
+	  .idVendor		= 0x046d,
+	  .idProduct		= 0x0821,
+	  .bInterfaceClass	= USB_CLASS_VIDEO,
+	  .bInterfaceSubClass	= 1,
+	  .bInterfaceProtocol	= 0,
+	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_WAKE_AUTOSUSPEND)},
+	/* Logitech, Webcam B910 */
+	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
+				| USB_DEVICE_ID_MATCH_INT_INFO,
+	  .idVendor		= 0x046d,
+	  .idProduct		= 0x0823,
+	  .bInterfaceClass	= USB_CLASS_VIDEO,
+	  .bInterfaceSubClass	= 1,
+	  .bInterfaceProtocol	= 0,
+	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_WAKE_AUTOSUSPEND)},
 	/* Logitech Quickcam Fusion */
 	{ .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 bc75c7c40251..fe5c7b465adf 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1984,6 +1984,16 @@ static int uvc_video_start_transfer(struct uvc_streaming *stream,
 			"Selecting alternate setting %u (%u B/frame bandwidth)\n",
 			altsetting, best_psize);
 
+		/*
+		 * Some devices, namely the Logitech C910 and B910, are unable
+		 * to recover from an USB autosuspend, unless the alternate
+		 * setting of the streaming interface is toggled.
+		 */
+		if (stream->dev->quirks & UVC_QUIRK_WAKE_AUTOSUSPEND) {
+			usb_set_interface(stream->dev->udev, intfnum,
+					  altsetting);
+			usb_set_interface(stream->dev->udev, intfnum, 0);
+		}
 		ret = usb_set_interface(stream->dev->udev, intfnum, altsetting);
 		if (ret < 0)
 			return ret;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 88d1790e6695..24c3e9411415 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -76,6 +76,7 @@
 #define UVC_QUIRK_FORCE_BPP		0x00001000
 #define UVC_QUIRK_IGNORE_EMPTY_TS	0x00002000
 #define UVC_QUIRK_INVALID_DEVICE_SOF	0x00004000
+#define UVC_QUIRK_WAKE_AUTOSUSPEND	0x00008000
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 6/8] media: uvcvideo: Allow hw clock updates with buffers not full

[Ricardo Ribalda]

With UVC 1.5 we get as little as one clock sample per frame. Which means
that it takes 32 frames to move from the software timestamp to the
hardware timestamp method.

This results in abrupt changes in the timestamping after 32 frames (~1
second), resulting in noticeable artifacts when used for encoding.

With this patch we modify the update algorithm to work with whatever
amount of values are available.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index fe5c7b465adf..5c37b080e0c6 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -743,10 +743,10 @@ void uvc_video_clock_update(struct uvc_streaming *stream,
 
 	spin_lock_irqsave(&clock->lock, flags);
 
-	if (clock->count < clock->size)
+	if (clock->count < 2)
 		goto done;
 
-	first = &clock->samples[clock->head];
+	first = &clock->samples[(clock->head - clock->count) % clock->size];
 	last = &clock->samples[(clock->head - 1) % clock->size];
 
 	/* First step, PTS to SOF conversion. */
@@ -761,6 +761,15 @@ void uvc_video_clock_update(struct uvc_streaming *stream,
 	if (y2 < y1)
 		y2 += 2048 << 16;
 
+	/*
+	 * Have at least 1/4 of a second of timestamps before we
+	 * try to do any calculation. Otherwise we do not have enough
+	 * precision. This value was determined by running Android CTS
+	 * on different devices.
+	 */
+	if ((y2 - y1) < (256 << 16))
+		goto done;
+
 	y = (u64)(y2 - y1) * (1ULL << 31) + (u64)y1 * (u64)x2
 	  - (u64)y2 * (u64)x1;
 	y = div_u64(y, x2 - x1);

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 7/8] media: uvcvideo: Refactor clock circular buffer

[Ricardo Ribalda]

Isolate all the changes related to the clock circular buffer to its own
function, that way we can make changes easier to the buffer logic.

Also simplify the lock, by removing the circular buffer clock handling
from uvc_video_clock_decode().

And now that we are at it, unify the API of the clock functions.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 81 ++++++++++++++++++---------------------
 1 file changed, 37 insertions(+), 44 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 5c37b080e0c6..2c6da49ff84b 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -464,18 +464,29 @@ static inline ktime_t uvc_video_get_time(void)
 		return ktime_get_real();
 }
 
+static void uvc_video_clock_add_sample(struct uvc_clock *clock,
+				       const struct uvc_clock_sample *sample)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&clock->lock, flags);
+
+	memcpy(&clock->samples[clock->head], sample, sizeof(*sample));
+	clock->last_sof = sample->dev_sof;
+	clock->head = (clock->head + 1) % clock->size;
+	clock->count = min(clock->count + 1, clock->size);
+
+	spin_unlock_irqrestore(&clock->lock, flags);
+}
+
 static void
 uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 		       const u8 *data, int len)
 {
-	struct uvc_clock_sample *sample;
+	struct uvc_clock_sample sample;
 	unsigned int header_size;
 	bool has_pts = false;
 	bool has_scr = false;
-	unsigned long flags;
-	ktime_t time;
-	u16 host_sof;
-	u16 dev_sof;
 
 	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 	case UVC_STREAM_PTS | UVC_STREAM_SCR:
@@ -531,20 +542,19 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * case only the first one will match the host_sof.
 	 */
 	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
-		dev_sof = usb_get_current_frame_number(stream->dev->udev);
+		sample.dev_sof =
+			usb_get_current_frame_number(stream->dev->udev);
 	else
-		dev_sof = get_unaligned_le16(&data[header_size - 2]);
+		sample.dev_sof = get_unaligned_le16(&data[header_size - 2]);
 
-	if (dev_sof == stream->clock.last_sof)
+	if (sample.dev_sof == stream->clock.last_sof)
 		return;
 
-	stream->clock.last_sof = dev_sof;
-
 	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
-		host_sof = dev_sof;
+		sample.host_sof = sample.dev_sof;
 	else
-		host_sof = usb_get_current_frame_number(stream->dev->udev);
-	time = uvc_video_get_time();
+		sample.host_sof = usb_get_current_frame_number(stream->dev->udev);
+	sample.host_time = uvc_video_get_time();
 
 	/*
 	 * The UVC specification allows device implementations that can't obtain
@@ -567,46 +577,29 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * the 8 LSBs of the delta are kept.
 	 */
 	if (stream->clock.sof_offset == (u16)-1) {
-		u16 delta_sof = (host_sof - dev_sof) & 255;
+		u16 delta_sof = (sample.host_sof - sample.dev_sof) & 255;
 		if (delta_sof >= 10)
 			stream->clock.sof_offset = delta_sof;
 		else
 			stream->clock.sof_offset = 0;
 	}
 
-	dev_sof = (dev_sof + stream->clock.sof_offset) & 2047;
-
-	spin_lock_irqsave(&stream->clock.lock, flags);
-
-	sample = &stream->clock.samples[stream->clock.head];
-	sample->dev_stc = get_unaligned_le32(&data[header_size - 6]);
-	sample->dev_sof = dev_sof;
-	sample->host_sof = host_sof;
-	sample->host_time = time;
-
-	/* Update the sliding window head and count. */
-	stream->clock.head = (stream->clock.head + 1) % stream->clock.size;
+	sample.dev_sof = (sample.dev_sof + stream->clock.sof_offset) & 2047;
+	sample.dev_stc = get_unaligned_le32(&data[header_size - 6]);
 
-	if (stream->clock.count < stream->clock.size)
-		stream->clock.count++;
-
-	spin_unlock_irqrestore(&stream->clock.lock, flags);
+	uvc_video_clock_add_sample(&stream->clock, &sample);
 }
 
-static void uvc_video_clock_reset(struct uvc_streaming *stream)
+static void uvc_video_clock_reset(struct uvc_clock *clock)
 {
-	struct uvc_clock *clock = &stream->clock;
-
 	clock->head = 0;
 	clock->count = 0;
 	clock->last_sof = -1;
 	clock->sof_offset = -1;
 }
 
-static int uvc_video_clock_init(struct uvc_streaming *stream)
+static int uvc_video_clock_init(struct uvc_clock *clock)
 {
-	struct uvc_clock *clock = &stream->clock;
-
 	spin_lock_init(&clock->lock);
 	clock->size = 32;
 
@@ -615,15 +608,15 @@ static int uvc_video_clock_init(struct uvc_streaming *stream)
 	if (clock->samples == NULL)
 		return -ENOMEM;
 
-	uvc_video_clock_reset(stream);
+	uvc_video_clock_reset(clock);
 
 	return 0;
 }
 
-static void uvc_video_clock_cleanup(struct uvc_streaming *stream)
+static void uvc_video_clock_cleanup(struct uvc_clock *clock)
 {
-	kfree(stream->clock.samples);
-	stream->clock.samples = NULL;
+	kfree(clock->samples);
+	clock->samples = NULL;
 }
 
 /*
@@ -2092,7 +2085,7 @@ int uvc_video_resume(struct uvc_streaming *stream, int reset)
 
 	stream->frozen = 0;
 
-	uvc_video_clock_reset(stream);
+	uvc_video_clock_reset(&stream->clock);
 
 	if (!uvc_queue_streaming(&stream->queue))
 		return 0;
@@ -2226,7 +2219,7 @@ int uvc_video_start_streaming(struct uvc_streaming *stream)
 {
 	int ret;
 
-	ret = uvc_video_clock_init(stream);
+	ret = uvc_video_clock_init(&stream->clock);
 	if (ret < 0)
 		return ret;
 
@@ -2244,7 +2237,7 @@ int uvc_video_start_streaming(struct uvc_streaming *stream)
 error_video:
 	usb_set_interface(stream->dev->udev, stream->intfnum, 0);
 error_commit:
-	uvc_video_clock_cleanup(stream);
+	uvc_video_clock_cleanup(&stream->clock);
 
 	return ret;
 }
@@ -2272,5 +2265,5 @@ void uvc_video_stop_streaming(struct uvc_streaming *stream)
 		usb_clear_halt(stream->dev->udev, pipe);
 	}
 
-	uvc_video_clock_cleanup(stream);
+	uvc_video_clock_cleanup(&stream->clock);
 }

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

[PATCH v3 8/8] media: uvcvideo: Fix hw timestamp handling for slow FPS

[Ricardo Ribalda]

In UVC 1.5 we get a single clock value per frame. With the current
buffer size of 32, FPS slowers than 32 might roll-over twice.

The current code cannot handle two roll-over and provide invalid
timestamps.

Revome all the samples from the circular buffer that are more than two
rollovers old, so the algorithm always provides good timestamps.

Note that we are removing values that are more than one second old,
which means that there is enough distance between the two points that
we use for the interpolation to provide good values.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 15 +++++++++++++++
 drivers/media/usb/uvc/uvcvideo.h  |  1 +
 2 files changed, 16 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 2c6da49ff84b..b0b93e218288 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -471,6 +471,20 @@ static void uvc_video_clock_add_sample(struct uvc_clock *clock,
 
 	spin_lock_irqsave(&clock->lock, flags);
 
+	/* Delete last overflows */
+	if (clock->head == clock->last_sof_overflow)
+		clock->last_sof_overflow = -1;
+
+	/* Handle overflows */
+	if (clock->count > 0 && clock->last_sof > sample->dev_sof) {
+		/* Remove data from the last^2 overflows */
+		if (clock->last_sof_overflow != -1)
+			clock->count = (clock->head - clock->last_sof_overflow)
+								% clock->count;
+		clock->last_sof_overflow = clock->head;
+	}
+
+	/* Add sample */
 	memcpy(&clock->samples[clock->head], sample, sizeof(*sample));
 	clock->last_sof = sample->dev_sof;
 	clock->head = (clock->head + 1) % clock->size;
@@ -595,6 +609,7 @@ static void uvc_video_clock_reset(struct uvc_clock *clock)
 	clock->head = 0;
 	clock->count = 0;
 	clock->last_sof = -1;
+	clock->last_sof_overflow = -1;
 	clock->sof_offset = -1;
 }
 
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 24c3e9411415..6dc015754e99 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -503,6 +503,7 @@ struct uvc_streaming {
 		unsigned int head;
 		unsigned int count;
 		unsigned int size;
+		unsigned int last_sof_overflow;
 
 		u16 last_sof;
 		u16 sof_offset;

-- 
2.39.0.314.g84b9a713c41-goog-b4-0.11.0-dev-696ae

Re: [PATCH v3 3/8] media: uvc: Create UVC_QUIRK_IGNORE_EMPTY_TS quirk

[Laurent Pinchart]

Hi Ricardo,

Thank you for the patch.

On Wed, Jan 04, 2023 at 11:45:21AM +0100, Ricardo Ribalda wrote:
> Some SunplusIT cameras took a borderline interpretation of the UVC 1.5
> standard, and fill the PTS and SCR fields with invalid data if the
> package does not contain data.
> 
> "STC must be captured when the first video data of a video frame is put
> on the USB bus."
> 
> Eg:
> 
> buffer: 0xa7755c00 len 000012 header:0x8c stc 00000000 sof 0000 pts 00000000
> buffer: 0xa7755c00 len 000012 header:0x8c stc 00000000 sof 0000 pts 00000000
> buffer: 0xa7755c00 len 000668 header:0x8c stc 73779dba sof 070c pts 7376d37a
> 
> This borderline/buggy interpretation has been implemented in a variety
> of devices, from directly SunplusIT and from other OEMs that rebrand
> SunplusIT products.
> 
> Luckily we can identify the affected modules by looking at the guid of
> one of the extension units:
> 
> VideoControl Interface Descriptor:
>   guidExtensionCode         {82066163-7050-ab49-b8cc-b3855e8d221d}
> 
> This patch adds a new quirk to take care of this.
> 
> lsusb of one of the affected cameras:
> 
> Bus 001 Device 003: ID 1bcf:2a01 Sunplus Innovation Technology Inc.
> Device Descriptor:
>   bLength                18
>   bDescriptorType         1
>   bcdUSB               2.01
>   bDeviceClass          239 Miscellaneous Device
>   bDeviceSubClass         2 ?
>   bDeviceProtocol         1 Interface Association
>   bMaxPacketSize0        64
>   idVendor           0x1bcf Sunplus Innovation Technology Inc.
>   idProduct          0x2a01
>   bcdDevice            0.02
>   iManufacturer           1 SunplusIT Inc
>   iProduct                2 HanChen Wise Camera
>   iSerial                 3 01.00.00
>   bNumConfigurations      1
> 
> Tested-by: HungNien Chen <hn.chen@sunplusit.com>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_driver.c | 11 +++++++++++
>  drivers/media/usb/uvc/uvc_video.c  | 10 ++++++++++
>  drivers/media/usb/uvc/uvcvideo.h   |  1 +
>  3 files changed, 22 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 5448576a8413..c5ab6e2d24c3 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1199,6 +1199,17 @@ static const struct uvc_entity_quirk {
>  	u8 guid[16];
>  	u32 quirks;
>  } uvc_entity_quirk[] = {
> +	/*
> +	 * Some SunPlusIT uvc 1.5 device firmware expects that packages with
> +	 * no frame data are ignored by the host. Therefore it does not clear
> +	 * the PTS/SCR bits in the header, and breaks the timestamp decode
> +	 * algorithm.
> +	 */
> +	{
> +		.guid = {0x82, 0x06, 0x61, 0x63, 0x70, 0x50, 0xab, 0x49,
> +			 0xb8, 0xcc, 0xb3, 0x85, 0x5e, 0x8d, 0x22, 0x1d},
> +		.quirks = UVC_QUIRK_IGNORE_EMPTY_TS,
> +	},
>  };
>  
>  static void uvc_entity_quirks(struct uvc_device *dev)
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index def079c7a6fd..f469c62bedca 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -500,6 +500,16 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
>  	if (len < header_size)
>  		return;
>  
> +	/*
> +	 * Some devices make a borderline interpreation of the UVC 1.5 standard

s/interpreation/interpretation/

> +	 * and the packets with no data contain undefined timestamps. Ignore

"and send packets with no data ..." ?

> +	 * such packages to avoid interfering with the clock interpolation

s/packages/packets/

> +	 * algorithm.
> +	 */
> +	if (stream->dev->quirks & UVC_QUIRK_IGNORE_EMPTY_TS &&
> +	    len == header_size)
> +		return;

I've sent a reply to v2 which I'll copy here:

Given that there may be no guarantee that the above GUID won't be used
by devices that don't exhibit this problem, I'm wondering if we couldn't
use a heuristics instead of a quirk. I'm thinking about something along
the lines of

        if (buf->bytesused == 0 && len == header_size && has_scr &&
            stc == 0 && sof == 0)

This will catch suspicious SCR values (stc == 0 && sof == 0) on empty
packets (len == header_size) sent before any data packet (buf->bytesused
== 0), which should handle the devices you have to support, and avoid
false positives (the stc == 0 && sof == 0 check is already quite
restrictive, adding buf->bytesused == 0 would limit the workaround to
packets before the first data packet).

With this we could drop patch 2/8.

> +
>  	/*
>  	 * Extract the timestamps:
>  	 *
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index df93db259312..c3424ae29339 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -74,6 +74,7 @@
>  #define UVC_QUIRK_RESTORE_CTRLS_ON_INIT	0x00000400
>  #define UVC_QUIRK_FORCE_Y8		0x00000800
>  #define UVC_QUIRK_FORCE_BPP		0x00001000
> +#define UVC_QUIRK_IGNORE_EMPTY_TS	0x00002000
>  
>  /* Format flags */
>  #define UVC_FMT_FLAG_COMPRESSED		0x00000001

-- 
Regards,

Laurent Pinchart

Re: [PATCH v3 5/8] media: uvcvideo: Quirk for autosuspend in Logitech B910 and C910

[Laurent Pinchart]

Hi Ricardo,

Thank you for the patch.

On Wed, Jan 04, 2023 at 11:45:23AM +0100, Ricardo Ribalda wrote:
> Logitech B910 and C910 firmware are unable to recover from an USB

s/an USB/a USB/

> autosuspend. When it resumes, the device is in a state where it only produces
> invalid frames. Eg:
> 
> $ echo 0xFFFF > /sys/module/uvcvideo/parameters/trace # enable verbose log
> $ yavta -c1 -n1 --file='frame#.jpg' --format MJPEG --size=1920x1080 /dev/video1
> [350438.435219] uvcvideo: uvc_v4l2_open
> [350438.529794] uvcvideo: Resuming interface 2
> [350438.529801] uvcvideo: Resuming interface 3
> [350438.529991] uvcvideo: Trying format 0x47504a4d (MJPG): 1920x1080.
> [350438.529996] uvcvideo: Using default frame interval 33333.3 us (30.0 fps).
> [350438.551496] uvcvideo: uvc_v4l2_mmap
> [350438.555890] uvcvideo: Device requested 3060 B/frame bandwidth.
> [350438.555896] uvcvideo: Selecting alternate setting 11 (3060 B/frame bandwidth).
> [350438.556362] uvcvideo: Allocated 5 URB buffers of 32x3060 bytes each.
> [350439.316468] uvcvideo: Marking buffer as bad (error bit set).
> [350439.316475] uvcvideo: Frame complete (EOF found).
> [350439.316477] uvcvideo: EOF in empty payload.
> [350439.316484] uvcvideo: frame 1 stats: 149/261/417 packets, 1/149/417 pts (early initial), 416/417 scr, last pts/stc/sof 2976325734/2978107243/249
> [350439.384510] uvcvideo: Marking buffer as bad (error bit set).
> [350439.384516] uvcvideo: Frame complete (EOF found).
> [350439.384518] uvcvideo: EOF in empty payload.
> [350439.384525] uvcvideo: frame 2 stats: 265/379/533 packets, 1/265/533 pts (early initial), 532/533 scr, last pts/stc/sof 2979524454/2981305193/316
> [350439.448472] uvcvideo: Marking buffer as bad (error bit set).
> [350439.448478] uvcvideo: Frame complete (EOF found).
> [350439.448480] uvcvideo: EOF in empty payload.
> [350439.448487] uvcvideo: frame 3 stats: 265/377/533 packets, 1/265/533 pts (early initial), 532/533 scr, last pts/stc/sof 2982723174/2984503144/382
> ...(loop)...
> 
> The devices can leave this invalid state if the alternate setting of
> the streaming interface is toggled.
> 
> This patch adds a quirk for this device so it can be autosuspended
> properly.
> 
> lsusb -v:
> Bus 001 Device 049: ID 046d:0821 Logitech, Inc. HD Webcam C910
> 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          0x0821 HD Webcam C910
>   bcdDevice            0.10
>   iManufacturer           0
>   iProduct                0
>   iSerial                 1 390022B0
>   bNumConfigurations      1
> 
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_driver.c | 18 ++++++++++++++++++
>  drivers/media/usb/uvc/uvc_video.c  | 10 ++++++++++
>  drivers/media/usb/uvc/uvcvideo.h   |  1 +
>  3 files changed, 29 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index c89a1eebe91c..be6ad9b732a2 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2525,6 +2525,24 @@ static const struct usb_device_id uvc_ids[] = {
>  	  .bInterfaceSubClass	= 1,
>  	  .bInterfaceProtocol	= 0,
>  	  .driver_info		= (kernel_ulong_t)&uvc_quirk_probe_minmax },
> +	/* Logitech, Webcam C910 */
> +	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
> +				| USB_DEVICE_ID_MATCH_INT_INFO,
> +	  .idVendor		= 0x046d,
> +	  .idProduct		= 0x0821,
> +	  .bInterfaceClass	= USB_CLASS_VIDEO,
> +	  .bInterfaceSubClass	= 1,
> +	  .bInterfaceProtocol	= 0,
> +	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_WAKE_AUTOSUSPEND)},
> +	/* Logitech, Webcam B910 */
> +	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
> +				| USB_DEVICE_ID_MATCH_INT_INFO,
> +	  .idVendor		= 0x046d,
> +	  .idProduct		= 0x0823,
> +	  .bInterfaceClass	= USB_CLASS_VIDEO,
> +	  .bInterfaceSubClass	= 1,
> +	  .bInterfaceProtocol	= 0,
> +	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_WAKE_AUTOSUSPEND)},
>  	/* Logitech Quickcam Fusion */
>  	{ .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 bc75c7c40251..fe5c7b465adf 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1984,6 +1984,16 @@ static int uvc_video_start_transfer(struct uvc_streaming *stream,
>  			"Selecting alternate setting %u (%u B/frame bandwidth)\n",
>  			altsetting, best_psize);
>  
> +		/*
> +		 * Some devices, namely the Logitech C910 and B910, are unable
> +		 * to recover from an USB autosuspend, unless the alternate

Same here.

> +		 * setting of the streaming interface is toggled.
> +		 */
> +		if (stream->dev->quirks & UVC_QUIRK_WAKE_AUTOSUSPEND) {
> +			usb_set_interface(stream->dev->udev, intfnum,
> +					  altsetting);
> +			usb_set_interface(stream->dev->udev, intfnum, 0);
> +		}

Missing blank line.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

I'll apply this patch to my tree independently from the rest of this
series with these small issues fixed locally.

>  		ret = usb_set_interface(stream->dev->udev, intfnum, altsetting);
>  		if (ret < 0)
>  			return ret;
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 88d1790e6695..24c3e9411415 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -76,6 +76,7 @@
>  #define UVC_QUIRK_FORCE_BPP		0x00001000
>  #define UVC_QUIRK_IGNORE_EMPTY_TS	0x00002000
>  #define UVC_QUIRK_INVALID_DEVICE_SOF	0x00004000
> +#define UVC_QUIRK_WAKE_AUTOSUSPEND	0x00008000
>  
>  /* Format flags */
>  #define UVC_FMT_FLAG_COMPRESSED		0x00000001
> 

-- 
Regards,

Laurent Pinchart