[PATCH v4 0/5] uvcvideo: Fixes for hw timestamping

[PATCH v4 0/5] 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 v4 (Thanks Laurent!):
- Rebase on top of pinchart/next/uvc
- Use heuristic for UVC_QUIRK_IGNORE_EMPTY_TS
- Link to v3: https://lore.kernel.org/r/20220920-resend-hwtimestamp-v3-0-db9faee7f47d@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 (5):
      media: uvc: Ignore empty TS packets
      media: uvcvideo: Quirk for invalid dev_sof in Logitech C922
      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 |   9 +++
 drivers/media/usb/uvc/uvc_video.c  | 123 ++++++++++++++++++++++++-------------
 drivers/media/usb/uvc/uvcvideo.h   |   2 +
 3 files changed, 91 insertions(+), 43 deletions(-)
---
base-commit: 73d6709376914f577a61bb29e596fa93ec66598c
change-id: 20220920-resend-hwtimestamp-b3e22729284d

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

[PATCH v4 1/5] media: uvc: Ignore empty TS packets

[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. So quirking based on VID:PID will be problematic.

All the affected modules have the following extension unit:
VideoControl Interface Descriptor:
  guidExtensionCode         {82066163-7050-ab49-b8cc-b3855e8d221d}

But the vendor plans to use that GUID in the future and fix the bug,
this means that we should use heuristic to figure out the broken
packets.

This patch takes 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_video.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index d4b023d4de7c..710165502b5b 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -478,6 +478,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	ktime_t time;
 	u16 host_sof;
 	u16 dev_sof;
+	u32 dev_stc;
 
 	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 	case UVC_STREAM_PTS | UVC_STREAM_SCR:
@@ -526,6 +527,18 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	if (dev_sof == stream->clock.last_sof)
 		return;
 
+	dev_stc = get_unaligned_le32(&data[header_size - 6]);
+
+	/*
+	 * Some devices make a borderline interpretation of the UVC 1.5 standard
+	 * and sends packets with no data contain undefined timestamps. Ignore
+	 * such packages to avoid interfering with the clock interpolation
+	 * algorithm.
+	 */
+	if (buf->bytesused == 0 && len == header_size &&
+	    dev_stc == 0 && dev_sof == 0)
+		return;
+
 	stream->clock.last_sof = dev_sof;
 
 	host_sof = usb_get_current_frame_number(stream->dev->udev);
@@ -564,7 +577,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	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_stc = dev_stc;
 	sample->dev_sof = dev_sof;
 	sample->host_sof = host_sof;
 	sample->host_time = time;

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

[PATCH v4 2/5] 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  | 8 +++++++-
 drivers/media/usb/uvc/uvcvideo.h   | 1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index c1e3c1fab976..eae88d0f420e 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2569,6 +2569,15 @@ 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 710165502b5b..ecd3c1292182 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -541,7 +541,13 @@ 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.
+	 */
+	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
+		dev_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 22656755a801..699c33bc24ed 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -73,6 +73,7 @@
 #define UVC_QUIRK_FORCE_Y8		0x00000800
 #define UVC_QUIRK_FORCE_BPP		0x00001000
 #define UVC_QUIRK_WAKE_AUTOSUSPEND	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 v4 3/5] 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 ecd3c1292182..ee0f40b9eae3 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -747,10 +747,10 @@ 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. */
@@ -765,6 +765,15 @@ 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 v4 4/5] 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 | 84 ++++++++++++++++++---------------------
 1 file changed, 39 insertions(+), 45 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index ee0f40b9eae3..02831cf0a00f 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -466,19 +466,28 @@ 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->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;
-	u32 dev_stc;
 
 	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 	case UVC_STREAM_PTS | UVC_STREAM_SCR:
@@ -523,11 +532,11 @@ 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 (dev_sof == stream->clock.last_sof)
+	sample.dev_sof = get_unaligned_le16(&data[header_size - 2]);
+	if (sample.dev_sof == stream->clock.last_sof)
 		return;
 
-	dev_stc = get_unaligned_le32(&data[header_size - 6]);
+	sample.dev_stc = get_unaligned_le32(&data[header_size - 6]);
 
 	/*
 	 * Some devices make a borderline interpretation of the UVC 1.5 standard
@@ -536,19 +545,21 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	 * algorithm.
 	 */
 	if (buf->bytesused == 0 && len == header_size &&
-	    dev_stc == 0 && dev_sof == 0)
+	    sample.dev_stc == 0 && sample.dev_sof == 0)
 		return;
 
-	stream->clock.last_sof = dev_sof;
+	stream->clock.last_sof = sample.dev_sof;
 
 	/*
 	 * 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.
 	 */
-	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
-		dev_sof = usb_get_current_frame_number(stream->dev->udev);
+	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF) {
+		sample.dev_sof =
+			usb_get_current_frame_number(stream->dev->udev);
+	}
 
-	time = uvc_video_get_time();
+	sample.host_time = uvc_video_get_time();
 
 	/*
 	 * The UVC specification allows device implementations that can't obtain
@@ -571,46 +582,29 @@ 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 = dev_stc;
-	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;
 
@@ -619,15 +613,15 @@ 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;
 }
 
 /*
@@ -2099,7 +2093,7 @@ 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;
@@ -2248,7 +2242,7 @@ 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;
 
@@ -2266,7 +2260,7 @@ 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;
 }
@@ -2294,5 +2288,5 @@ 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 v4 5/5] 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 02831cf0a00f..04f452d95fd6 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -473,6 +473,20 @@ 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->head = (clock->head + 1) % clock->size;
 	clock->count = min(clock->count + 1, clock->size);
@@ -600,6 +614,7 @@ 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 699c33bc24ed..f2a7e1507492 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -501,6 +501,7 @@ 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 v4 1/5] media: uvc: Ignore empty TS packets

[Dan Carpenter]

Hi Ricardo,

url:    https://github.com/intel-lab-lkp/linux/commits/Ricardo-Ribalda/media-uvc-Ignore-empty-TS-packets/20230109-180318
base:   73d6709376914f577a61bb29e596fa93ec66598c
patch link:    https://lore.kernel.org/r/20220920-resend-hwtimestamp-v4-1-a8ddc1358a29%40chromium.org
patch subject: [PATCH v4 1/5] media: uvc: Ignore empty TS packets
config: arc-randconfig-m031-20230108
compiler: arceb-elf-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>

smatch warnings:
drivers/media/usb/uvc/uvc_video.c:538 uvc_video_clock_decode() error: we previously assumed 'buf' could be null (see line 514)

vim +/buf +538 drivers/media/usb/uvc/uvc_video.c

66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  469  static void
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  470  uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
2c6b222cee2d68e drivers/media/usb/uvc/uvc_video.c   Laurent Pinchart 2018-01-16  471  		       const u8 *data, int len)
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  472  {
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  473  	struct uvc_clock_sample *sample;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  474  	unsigned int header_size;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  475  	bool has_pts = false;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  476  	bool has_scr = false;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  477  	unsigned long flags;
828ee8c71950155 drivers/media/usb/uvc/uvc_video.c   Arnd Bergmann    2017-11-27  478  	ktime_t time;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  479  	u16 host_sof;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  480  	u16 dev_sof;
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  481  	u32 dev_stc;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  482  
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  483  	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  484  	case UVC_STREAM_PTS | UVC_STREAM_SCR:
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  485  		header_size = 12;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  486  		has_pts = true;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  487  		has_scr = true;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  488  		break;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  489  	case UVC_STREAM_PTS:
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  490  		header_size = 6;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  491  		has_pts = true;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  492  		break;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  493  	case UVC_STREAM_SCR:
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  494  		header_size = 8;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  495  		has_scr = true;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  496  		break;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  497  	default:
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  498  		header_size = 2;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  499  		break;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  500  	}
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  501  
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  502  	/* Check for invalid headers. */
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  503  	if (len < header_size)
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  504  		return;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  505  
699b9a86a3f03ad drivers/media/usb/uvc/uvc_video.c   Laurent Pinchart 2022-06-08  506  	/*
699b9a86a3f03ad drivers/media/usb/uvc/uvc_video.c   Laurent Pinchart 2022-06-08  507  	 * Extract the timestamps:
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  508  	 *
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  509  	 * - store the frame PTS in the buffer structure
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  510  	 * - if the SCR field is present, retrieve the host SOF counter and
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  511  	 *   kernel timestamps and store them with the SCR STC and SOF fields
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  512  	 *   in the ring buffer
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  513  	 */
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24 @514  	if (has_pts && buf != NULL)
                                                                                                       ^^^^^^^^^^^
This code checks for NULL.

66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  515  		buf->pts = get_unaligned_le32(&data[2]);
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  516  
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  517  	if (!has_scr)
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  518  		return;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  519  
699b9a86a3f03ad drivers/media/usb/uvc/uvc_video.c   Laurent Pinchart 2022-06-08  520  	/*
699b9a86a3f03ad drivers/media/usb/uvc/uvc_video.c   Laurent Pinchart 2022-06-08  521  	 * To limit the amount of data, drop SCRs with an SOF identical to the
a919bd4d768164c drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-04  522  	 * previous one. This filtering is also needed to support UVC 1.5, where
a919bd4d768164c drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-04  523  	 * all the data packets of the same frame contains the same SOF. In that
a919bd4d768164c drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-04  524  	 * case only the first one will match the host_sof.
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  525  	 */
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  526  	dev_sof = get_unaligned_le16(&data[header_size - 2]);
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  527  	if (dev_sof == stream->clock.last_sof)
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  528  		return;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  529  
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  530  	dev_stc = get_unaligned_le32(&data[header_size - 6]);
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  531  
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  532  	/*
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  533  	 * Some devices make a borderline interpretation of the UVC 1.5 standard
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  534  	 * and sends packets with no data contain undefined timestamps. Ignore
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  535  	 * such packages to avoid interfering with the clock interpolation
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  536  	 * algorithm.
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  537  	 */
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09 @538  	if (buf->bytesused == 0 && len == header_size &&
                                                                                            ^^^^^^^^^^^^^^
Unchecked dereference

febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  539  	    dev_stc == 0 && dev_sof == 0)
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  540  		return;
febd4163e286059 drivers/media/usb/uvc/uvc_video.c   Ricardo Ribalda  2023-01-09  541  
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  542  	stream->clock.last_sof = dev_sof;
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  543  
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  544  	host_sof = usb_get_current_frame_number(stream->dev->udev);
828ee8c71950155 drivers/media/usb/uvc/uvc_video.c   Arnd Bergmann    2017-11-27  545  	time = uvc_video_get_time();
66847ef013cc4ed drivers/media/video/uvc/uvc_video.c Laurent Pinchart 2011-09-24  546  
699b9a86a3f03ad drivers/media/usb/uvc/uvc_video.c   Laurent Pinchart 2022-06-08  547  	/*

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests