Re: Dell XPS 12 USB camera bulk mode issues

[Mark Ryan <mark.d.ryan@linux.intel.com>]

Hi Laurent,

Thank you so much for your detailed response.

On 02/26/2014 04:40 PM, Laurent Pinchart wrote:
> Hi Mark,
>
> On Wednesday 26 February 2014 10:20:06 Ryan, Mark D wrote:
>> On Tuesday, February 25, 2014 10:50 PM Sarah Sharp wrote:
>>>
>>> Hi Laurent and Mauro,
>>>
>>> Mark has running into issues with the Realtek integrated webcam on a Dell
>>> XPS 12 system that uses bulk endpoints.  The webcam shows visible glitches
>>> with certain resolutions (stripes of frame missing, distorted images,
>>> purple and green colors, blank image, or missing the bottom half of the
>>> image).
>>
>>   [Ryan, Mark D]
>>
>> Sarah, thanks for the introduction.
>>
>> I can provide a little bit more information.
>>
>> 1. I've tried all the UVC driver quirks but none of these seem to help.
>
> That was a good idea, but there's no quirk for this kind of issue I'm afraid.
>
>> 2. I've also run some tests with the UVC traces enabled.  There are quite a
>> lot of errors.  I include a portion of the logs below.  They were generated
>> on Ubuntu 13.10 (linux 3.11.0-12) running guvcview recording YVUV 1280x720
>> at 10fps.
>
> You can set the trace parameter to 0x7bf in future tests to remove messages
> regarding the V4L2 API calls and timestamp statistics, it will make the log
> slightly more readable.
>
> Sarah has sent me two usbmon traces, one in a working case and the other in a
> non-working case. They unfortunately look both correct to me, so I'll likely
> need your help to debug this.
>
> Let's start with a bit of background information. I'll skip the UVC control
> protocol as that's not relevant to this discussion, except to mention that UVC
> uses control messages to negotiate the video format with the device, and
> receives the maximum payload transfer size (more about this below) from the
> device. Here's URB 61 in the non-working trace that commits the streaming
> parameters to the device (the maximum payload transfer size has been retrieved
> from the device previously and is committed without being modified by the
> driver).
>
> URB   Timestamp    Event       Address Type     Direction  Endpoint
> 61    2558.416852  Submission  4       Control  OUT        0
>
> SETUP Host-to-device Class request to Interface
> bRequest: SET CUR (01)
> wValue: 0200
> wIndex: INTF 1 ENTITY 0 (0001)
> wLength: 001a
>
> 26 data bytes
> bmHint                         0x01
> bFormatIndex                      2
> bFrameIndex                       3
> dwFrameInterval              333333
> wKeyFrameRate                     0
> wPFrameRate                       0
> wCompQuality                      0
> wCompWindowSize                   0
> wDelay                           32
> dwMaxVideoFrameSize          115200
> dwMaxPayloadTransferSize      43008
>
> You can find the script I use to decode the usbmon trace at
> http://www.ideasonboard.org/uvc/usbmon.py. Run it with the -C uvc option to
> decode the UVC protocol. You can also use the -a option to filter the URBs
> based on the device address.
>
> The equivalent URB in the working case is URB 101, and contains the following
> payload.
>
> SETUP Host-to-device Class request to Interface
> bRequest: SET CUR (01)
> wValue: 0200
> wIndex: INTF 1 ENTITY 0 (0001)
> wLength: 001a
>
> 26 data bytes
> bmHint                         0x01
> bFormatIndex                      2
> bFrameIndex                       4
> dwFrameInterval              333333
> wKeyFrameRate                     0
> wPFrameRate                       0
> wCompQuality                      0
> wCompWindowSize                   0
> wDelay                           32
> dwMaxVideoFrameSize          153600
> dwMaxPayloadTransferSize      43008
>
> The only differences are the bFrameIndex (used to select the resolution) and
> the dwMaxVideoFrameSize (the maximum size of the compressed frame, computed by
> the device as a worst case estimate using the size of the frame after
> decompression) values. The maximum payload transfer size is identical in the
> two cases. Nothing unexpected so far.
>
> After those URBs the uvcvideo driver starts submitting bulk URBs and get frame
> data back from the device. The device returns the following data in the first
> URB for the non-working and working cases respectively.
>
>    16262 data bytes
> 58595a63 64656667    XYZcdefg
> 68696a73 74757677    hijstuvw
> 78797a82 83848586    xyz‚ƒ„…†
> 8788898a 92939495    ‡ˆ‰Š’“”•
>
>    16262 data bytes
> 58595a63 64656667    XYZcdefg
> 68696a73 74757677    hijstuvw
> 78797a82 83848586    xyz‚ƒ„…†
> 8788898a 92939495    ‡ˆ‰Š’“”•
>
> The first few data bytes stored in the usbmon capture look like MJPEG Huffman
> table data. This is a violation of the UVC specification, the camera is
> supposed to start sending frames immediately. Furthermore, every payload must
> start with a UVC header, which is clearly not the case here.
>
> We're getting to the concept of payloads. UVC cuts frames in payloads that are
> then transmitted over isochronous or bulk endpoints. Payloads have a variable
> size with a fixed maximum size, and each payload starts with a UVC payload
> header. When using isochronous transfers each isochronous URB contains a
> single payload. When using bulk transfers payloads can be split across
> multiple bulk URBs. Each isochronous URB thus starts with a UVC header, while
> only the first bulk URB in a payload includes a header, the other containing
> frame data only.
>
> UVC headers start with a byte that contains the size of the header, followed
> by a byte containing the following flags.
>
> #define UVC_STREAM_EOH                                  (1 << 7)
> #define UVC_STREAM_ERR                                  (1 << 6)
> #define UVC_STREAM_STI                                  (1 << 5)
> #define UVC_STREAM_RES                                  (1 << 4)
> #define UVC_STREAM_SCR                                  (1 << 3)
> #define UVC_STREAM_PTS                                  (1 << 2)
> #define UVC_STREAM_EOF                                  (1 << 1)
> #define UVC_STREAM_FID                                  (1 << 0)
>
> EOH stands for End-Of-Header and is in practice always set. ERR denotes an
> error in the payload, STI denotes a still image (never set for video-only
> devices), RES is reserved, SCR and PTS are related to timestamp information
> contained in the header (the header contains 4 bytes of source clock data when
> SCR is set, and 6 bytes of presentation timestamp when PTS is set), EOF stands
> for End-Of-Frame and marks the last payload of a frame, and FID stands for
> Frame-Identifier and toggles with every frame.
>
> A payload ends either when the maximum payload size has been reached, or when
> a short bulk URB is transferred. Looking at the working capture trace, we get
> a repeating pattern of the following URBs.
>
>    16384 data bytes
> 0c8c026c 46e15af8    .Œ.lFáZø
> 4de15a05 ffd8ffdb    MáZ.ÿØÿÛ
> 00430003 02020202    .C......
> 02030202 02030303    ........
>
>    378 data bytes
> bed94ee3 bba0acab    ¾ÙNã» ¬«
> b5460d1d 5422ea34    µF..T"ê4
> d995a878 89df558a    Ù•¨x‰ßUŠ
> ded9f309 5c11fdea    ÞÙó.\.ýê
>
>    14 data bytes
> 0c8e026c 46e1530e    .Ž.lFáS.
> 4ee15a05 ffd9        NáZ.ÿÙ
>
> The first URB starts a payload and thus contains a header, starting with 0x0c
> 0x8c. This translates to 12 bytes of header data and the EOH, SCR and PTS
> bits. As SCR and PTS are set the header is expected to be 2 + 4 + 6 bytes
> long, which is correct. The EOF bit isn't set, so the payload isn't the last
> of the frame, and the FID bit is 0. The number of bytes transferred so far
> (16384) is smaller than the maximum payload size negotiated earlier, so the
> payload isn't finished.
>
> The second URB thus doesn't start by a header as it continues the payload. It
> contains frame data only. The URB is a short URB, and thus completes the
> payload (but not the frame).
>
> The third URB starts with a 12-byte header with the EOH, SCR, PTS and EOF bits
> set, and contains two more bytes of data (0xff 0xd9) that are expected at the
> end of the MJPEG frame. As the EOF bit is set the frame is now complete, and
> as the URB is short the payload is complete as well.
>
> The next three URBs are similar but have the FID header bit set this time, as
> the bit is required to be toggled for every frame. The pattern then repeats.
>
> The non-working case has the following pattern.
>
>    13334 data bytes
> 0c8cb210 18147994    .Œ²...y”
> 1f146203 ffd8ffdb    ..b.ÿØÿÛ
> 00430003 02020202    .C......
> 02030202 02030303    ........
>
>    14 data bytes
> 0c8eb210 181472aa    .Ž²...rª
> 1f146203 ffd9        ..b.ÿÙ
>
> The first URB starts with a header but is now a short URB and thus completes
> the payload. The second URB completes the frame. Nothing unexpected, the
> resolution is lower so we need less URBs to transfer a frame.
>
> The driver should handle both cases correctly. A quick analysis also indicates
> that the driver shouldn't get confused by the first incorrect URB, but I might
> be wrong.
>
> Looking below it looks like the driver is completely desynchronized with the
> payload headers. This would explain the symptoms that Sarah reported, as the
> driver could then interpret data as payload headers and base its state machine
> on random FID and EOF bits.
>
> With the information I've given you, could you try to log more information in
> the driver to try and find what goes wrong ? You could for instance log the
> content of each header at the beginning of the uvc_video_decode_start()
> function.

I can indeed.  I'll get back to you in the next few days with some more 
detailed logs.

>
>> [   80.490256] uvcvideo: Frame complete (FID bit toggled).
>> [   80.490262] uvcvideo: frame 2080 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2069725020/32605 [   80.490264]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.490606] uvcvideo: Frame complete (EOF found).
>> [   80.490942] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.490947] uvcvideo: Dropping payload (out of sync).
>> [   80.492920] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.492927] uvcvideo: Dropping payload (out of sync).
>> [   80.495352] uvcvideo: frame 2081 stats: 0/0/3 packets, 0/0/1 pts (!early
>> !initial), 2/3 scr, last pts/stc/sof 2103017049/2069659484/32604 [
>> 80.495360] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.496066] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.498021] uvcvideo: frame 2082 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2103148379/2103148379/32601 [
>> 80.498030] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.498033] uvcvideo: Frame complete (FID bit toggled).
>> [   80.498039] uvcvideo: frame 2083 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2103213661/2103213661/32349 [
>> 80.498042] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.500420] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.501122] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.502742] uvcvideo: Frame complete (EOF found).
>> [   80.503095] uvcvideo: frame 2084 stats: 0/0/3 packets, 1/1/2 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2102754899/2069659484/32604 [
>> 80.503100] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.505510] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.505890] uvcvideo: Frame complete (EOF found).
>> [   80.506245] uvcvideo: frame 2085 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2119532118/2119532118/32341 [
>> 80.506249] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.507845] uvcvideo: Frame complete (EOF found).
>> [   80.508187] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.508191] uvcvideo: Dropping payload (out of sync).
>> [   80.510747] uvcvideo: frame 2086 stats: 0/0/2 packets, 0/0/1 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2137357669/2085781330/32594 [
>> 80.510752] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.511463] uvcvideo: frame 2087 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2081456144/2081456144/32784 [
>> 80.511471] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.511474] uvcvideo: Frame complete (FID bit toggled).
>> [   80.511480] uvcvideo: frame 2088 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102493775/2102559313/33362 [
>> 80.511483] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.513895] uvcvideo: frame 2089 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102493775/2102559313/33362 [
>> 80.513904] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.513907] uvcvideo: Frame complete (FID bit toggled).
>> [   80.513913] uvcvideo: frame 2090 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2086567773/2086502238/32605 [
>> 80.513916] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.514608] uvcvideo: frame 2091 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2086567773/2086502238/32605 [
>> 80.514617] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.514620] uvcvideo: Frame complete (FID bit toggled).
>> [   80.514626] uvcvideo: frame 2092 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102754901/2102754901/32341 [
>> 80.514629] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.517141] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.517858] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.520396] uvcvideo: frame 2093 stats: 0/0/3 packets, 2/2/3 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2098429971/2098692119/32792 [
>> 80.520404] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.520407] uvcvideo: Frame complete (FID bit toggled).
>> [   80.520413] uvcvideo: frame 2094 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2081456656/2081456656/33296 [
>> 80.520416] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.521111] uvcvideo: frame 2095 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2081456656/2081456656/33296 [
>> 80.521119] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.521122] uvcvideo: Frame complete (FID bit toggled).
>> [   80.521128] uvcvideo: frame 2096 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102951768/2102820696/32598 [
>> 80.521131] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.523496] uvcvideo: frame 2097 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102951768/2102820696/32598 [
>> 80.523505] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.523508] uvcvideo: Frame complete (FID bit toggled).
>> [   80.523514] uvcvideo: frame 2098 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2119794008/2119728472/32088 [
>> 80.523517] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.523831] uvcvideo: Frame complete (EOF found).
>> [   80.525463] uvcvideo: Dropping payload (out of sync).
>> [   80.526190] uvcvideo: frame 2099 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 96354447/97436625/437 [   80.526199]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.528590] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.530563] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.531249] uvcvideo: frame 2100 stats: 0/0/3 packets, 2/2/3 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2102558546/2102624083/32595 [
>> 80.531258] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.531261] uvcvideo: Frame complete (FID bit toggled).
>> [   80.531267] uvcvideo: frame 2101 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2119401555/2119401555/32851 [
>> 80.531270] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.533319] uvcvideo: Frame complete (EOF found).
>> [   80.533683] uvcvideo: frame 2102 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2119401555/2119401555/32851 [
>> 80.533692] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.535641] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.536353] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.538778] uvcvideo: frame 2103 stats: 0/0/3 packets, 2/2/3 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2102361937/2102361935/32591 [
>> 80.538787] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.538790] uvcvideo: Frame complete (FID bit toggled).
>> [   80.538796] uvcvideo: frame 2104 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2117435189/2100657973/32567 [
>> 80.538799] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.539116] uvcvideo: Frame complete (EOF found).
>> [   80.540751] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.540758] uvcvideo: Dropping payload (out of sync).
>> [   80.542582] uvcvideo: frame 2105 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2119270481/2119336018/32850 [
>> 80.542593] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.543286] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.545268] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.547699] uvcvideo: frame 2106 stats: 0/0/3 packets, 2/2/3 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2101378880/2101247806/32574 [
>> 80.547707] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.547710] uvcvideo: Frame complete (FID bit toggled).
>> [   80.547716] uvcvideo: frame 2107 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2118811466/2101903434/32840 [
>> 80.547719] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.548047] uvcvideo: Frame complete (EOF found).
>> [   80.548394] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.548401] uvcvideo: Dropping payload (out of sync).
>> [   80.550362] uvcvideo: frame 2108 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2085125960/2085060423/32582 [
>> 80.550371] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.552830] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.553372] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.561825] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.562162] uvcvideo: Frame complete (EOF found).
>> [   80.562497] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.562505] uvcvideo: Dropping payload (out of sync).
>> [   80.564927] uvcvideo: frame 2109 stats: 0/0/6 packets, 3/3/4 pts (!early
>> initial), 5/6 scr, last pts/stc/sof 97857347/2068480074/32842 [
>> 80.564935] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.566925] uvcvideo: frame 2110 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2069069907/2069069907/32851 [
>> 80.566934] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.566937] uvcvideo: Frame complete (FID bit toggled).
>> [   80.566943] uvcvideo: frame 2111 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102558546/2102493009/32593 [
>> 80.566946] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.567599] uvcvideo: frame 2112 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102558546/2102493009/32593 [
>> 80.567607] uvcvideo: Frame complete (FID bit toggled).
>> [   80.567613] uvcvideo: frame 2113 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/0 scr, last pts/stc/sof 0/0/0 [   80.570041] uvcvideo: frame
>> 2114 stats: 0/0/1 packets, 0/0/0 pts (!early !initial), 0/0 scr, last
>> pts/stc/sof 0/0/0 [   80.570050] uvcvideo: Marking buffer as bad (error bit
>> set).
>> [   80.570053] uvcvideo: Frame complete (FID bit toggled).
>> [   80.570059] uvcvideo: frame 2115 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2068938833/32849 [   80.570062]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.570379] uvcvideo: Frame complete (EOF found).
>> [   80.572032] uvcvideo: frame 2116 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2068938833/32849 [   80.572041]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.572713] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.575138] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.577804] uvcvideo: frame 2117 stats: 0/0/4 packets, 2/2/3 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2084667459/2084470848/32830 [
>> 80.577813] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.577816] uvcvideo: Frame complete (FID bit toggled).
>> [   80.577822] uvcvideo: frame 2118 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2069004371/32851 [   80.577825]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.578143] uvcvideo: Frame complete (EOF found).
>> [   80.580219] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.580223] uvcvideo: Dropping payload (out of sync).
>> [   80.582212] uvcvideo: frame 2119 stats: 0/0/2 packets, 0/0/0 pts (!early
>> !initial), 1/2 scr, last pts/stc/sof 0/2069266518/32854 [   80.582221]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.582896] uvcvideo: frame 2120 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2086371163/2086371163/32604 [
>> 80.582904] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.582907] uvcvideo: Frame complete (FID bit toggled).
>> [   80.582913] uvcvideo: frame 2121 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102951768/2102951768/32600 [
>> 80.582916] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.584748] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.586723] uvcvideo: frame 2122 stats: 0/0/2 packets, 0/0/1 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2102951768/2036039771/32859 [
>> 80.586731] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.586734] uvcvideo: Frame complete (FID bit toggled).
>> [   80.586740] uvcvideo: frame 2123 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2052489304/32856 [   80.586743]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.587067] uvcvideo: Frame complete (EOF found).
>> [   80.588555] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.588564] uvcvideo: Dropping payload (out of sync).
>> [   80.590556] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.590564] uvcvideo: Dropping payload (out of sync).
>> [   80.591231] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.591239] uvcvideo: Dropping payload (out of sync).
>> [   80.593662] uvcvideo: frame 2124 stats: 0/0/4 packets, 2/3/3 pts (!early
>> !initial), 3/4 scr, last pts/stc/sof 2086240088/2086240089/32601 [
>> 80.593670] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.593995] uvcvideo: Frame complete (EOF found).
>> [   80.595639] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.595646] uvcvideo: Dropping payload (out of sync).
>> [   80.596344] uvcvideo: frame 2125 stats: 0/0/2 packets, 0/0/1 pts (!early
>> !initial), 1/2 scr, last pts/stc/sof 2081456144/2081456144/32784 [
>> 80.596353] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.598768] uvcvideo: frame 2126 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2086371161/2086240091/32601 [
>> 80.598776] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.598779] uvcvideo: Frame complete (FID bit toggled).
>> [   80.598785] uvcvideo: frame 2127 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2103213916/2103279453/32605 [
>> 80.598788] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.600741] uvcvideo: frame 2128 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2103213916/2103279453/32605 [
>> 80.600749] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.600753] uvcvideo: Frame complete (FID bit toggled).
>> [   80.600758] uvcvideo: frame 2129 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102755157/2102624085/32595 [
>> 80.600761] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.601436] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.603280] uvcvideo: frame 2130 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2086502237/2086502237/32605 [
>> 80.603288] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.603291] uvcvideo: Frame complete (FID bit toggled).
>> [   80.603297] uvcvideo: frame 2131 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2066711095/33331 [   80.603300]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.604922] uvcvideo: Frame complete (EOF found).
>> [   80.605261] uvcvideo: frame 2132 stats: 0/0/1 packets, 0/0/0 pts (!early
>> !initial), 0/1 scr, last pts/stc/sof 0/2066711095/33331 [   80.605270]
>> uvcvideo: Marking buffer as bad (error bit set).
>> [   80.605627] uvcvideo: Frame complete (EOF found).
>> [   80.605982] uvcvideo: frame 2133 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2119532117/2119597654/32342 [
>> 80.605990] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.608029] uvcvideo: Frame complete (EOF found).
>> [   80.608384] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.608391] uvcvideo: Dropping payload (out of sync).
>> [   80.610344] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.610353] uvcvideo: Dropping payload (out of sync).
>> [   80.612192] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.612196] uvcvideo: Dropping payload (out of sync).
>> [   80.612941] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.612948] uvcvideo: Dropping payload (out of sync).
>> [   80.615462] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.615469] uvcvideo: Dropping payload (out of sync).
>> [   80.616182] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.616190] uvcvideo: Dropping payload (out of sync).
>> [   80.618717] uvcvideo: frame 2134 stats: 0/0/7 packets, 4/6/5 pts (!early
>> initial), 6/7 scr, last pts/stc/sof 2102296398/2102165324/32588 [
>> 80.618726] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.619425] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.621815] uvcvideo: frame 2135 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2081456656/2081456656/33296 [
>> 80.621824] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.621827] uvcvideo: Frame complete (FID bit toggled).
>> [   80.621834] uvcvideo: frame 2136 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2102820693/2102820694/32600 [
>> 80.621837] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.623785] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.626895] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.628846] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.630705] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.632698] uvcvideo: frame 2137 stats: 0/0/6 packets, 5/5/6 pts (!early
>> initial), 5/6 scr, last pts/stc/sof 2102558546/2102558546/32594 [
>> 80.632706] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.632709] uvcvideo: Frame complete (FID bit toggled).
>> [   80.632715] uvcvideo: frame 2138 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2119336019/2102558802/32850 [
>> 80.632718] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.633058] uvcvideo: Frame complete (EOF found).
>> [   80.633403] uvcvideo: frame 2139 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2119336019/2102558802/32850 [
>> 80.633412] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.635832] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.637813] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.638509] uvcvideo: frame 2140 stats: 0/0/3 packets, 2/2/3 pts (!early
>> initial), 2/3 scr, last pts/stc/sof 2102493009/2102493009/32593 [
>> 80.638523] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.638527] uvcvideo: Frame complete (FID bit toggled).
>> [   80.638537] uvcvideo: frame 2141 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2117435445/2100723765/32824 [
>> 80.638541] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.638817] uvcvideo: Frame complete (EOF found).
>> [   80.641019] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.641028] uvcvideo: Dropping payload (out of sync).
>> [   80.641709] uvcvideo: frame 2142 stats: 0/0/2 packets, 1/1/2 pts (!early
>> initial), 1/2 scr, last pts/stc/sof 2102362191/2102493265/32847 [
>> 80.641719] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.644143] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.646129] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.646798] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.649234] uvcvideo: frame 2143 stats: 0/0/4 packets, 3/3/4 pts (!early
>> initial), 3/4 scr, last pts/stc/sof 2101903432/2102034506/32844 [
>> 80.649243] uvcvideo: Marking buffer as bad (error bit set).
>> [   80.649247] uvcvideo: Frame complete (FID bit toggled).
>> [   80.649254] uvcvideo: frame 2144 stats: 0/0/1 packets, 0/0/1 pts (!early
>> initial), 0/1 scr, last pts/stc/sof 2085060423/2084994887/32582 [
>> 80.649256] uvcvideo: Marking buffer as bad (error bit set).
>