前面我们在https://mp.weixin.qq.com/s/s3uC-SHaVcXWAZK1sK6EZw?token=6568576&lang=zh_CN
《WSL2中配置支持UVC》一文中，分享了重新编译WSL2内核以支持UVC。
基于此,我们能随意修改内核重新编译加载新的内核运行，这样我们就可以方便的在PC上进行UVC相关的调试了。这一篇就来分享一个具体的案例。
我们调试的主要手段就是打开UVC代码中的dbg调试打印，通过打印信息来确认执行流，状态等。 当然现在我们可以随意修改内核代码了，那么我们就可以在关心的位置添加我们自己的打印信息方便调试。
在drivers/media/usb/uvc/uvc_driver.c中，通过以下语句定义了一个调试使能的参数
unsigned int uvc_dbg_param;
module_param_named(trace, uvc_dbg_param, uint, S_IRUGO|S_IWUSR);
最终的效果就是生成对应的文件
/sys/module/uvcvideo/parameters/trace
修改上述文件trace实际对应的就是修改变量uvc_dbg_param
类似的所有其他的参数如下
MODULE_PARM_DESC(clock, "Video buffers timestamp clock");module_param_named(hwtimestamps, uvc_hw_timestamps_param, uint, S_IRUGO|S_IWUSR);MODULE_PARM_DESC(hwtimestamps, "Use hardware timestamps");module_param_named(nodrop, uvc_no_drop_param, uint, S_IRUGO|S_IWUSR);MODULE_PARM_DESC(nodrop, "Don't drop incomplete frames");module_param_named(quirks, uvc_quirks_param, uint, S_IRUGO|S_IWUSR);MODULE_PARM_DESC(quirks, "Forced device quirks");module_param_named(trace, uvc_dbg_param, uint, S_IRUGO|S_IWUSR);MODULE_PARM_DESC(trace, "Trace level bitmask");module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
drivers/media/usb/uvc/uvcvideo.h中
调试打印接口，调用的时dev_printk, 根据uvc_dbg_param变量的具体某一位是否置位(与UVC_DBG_##flag与)来判断是否要打印，flag是传入的分类名，比如PROBE对应的是 UVC_DBG_PROBE，bit0，如果uvc_dbg_param的bit0置位，则uvc_dbg(stream->dev, PROBE,对应的就会打印。
do { \if (uvc_dbg_param & UVC_DBG_##flag) \dev_printk(KERN_DEBUG, &(_dev)->udev->dev, fmt, \##__VA_ARGS__); \} while (0)#define UVC_DBG_PROBE (1 << 0)#define UVC_DBG_DESCR (1 << 1)#define UVC_DBG_CONTROL (1 << 2)#define UVC_DBG_FORMAT (1 << 3)#define UVC_DBG_CAPTURE (1 << 4)#define UVC_DBG_CALLS (1 << 5)#define UVC_DBG_FRAME (1 << 7)#define UVC_DBG_SUSPEND (1 << 8)#define UVC_DBG_STATUS (1 << 9)#define UVC_DBG_VIDEO (1 << 10)#define UVC_DBG_STATS (1 << 11)#define UVC_DBG_CLOCK (1 << 12)
具体操作如下
Shell中查看参数，
上述的参数对应的文件位于对于/sys/module/{模块名}/parameters/
，对于uvc模块名为uvcvideo，所以对应/sys/module/uvcvideo/parameters/
查看如下
root@lhj:/home/lhj# ls /sys/module/uvcvideo/parameters/
clock hwtimestamps nodrop quirks timeout trace
root@lhj:/home/lhj#
所以只需要按照如下操作，这里是配置 uvc_dbg_param的bit0~bit12都置位，使能所有类别的打印。
sudo su
echo 0x01FFF > /sys/module/uvcvideo/parameters/trace
cat /sys/module/uvcvideo/parameters/trace
显示8191
su qinyunti
以上使能之后就可以dmesg查看调试输出了。
我们这里以一个具体的案例来分享，UVC增加双设备支持后，在windows下可以双设备同时显示，在linux下只能单独显示，打开一个设备后再打开另一个设备导致两个设备都不能显示，关闭一个设备后另一个设备能显示。
我们找到UVC probe关键的代码增加一些打印信息，当然具体情况具体分析，一般在关键路径增加一些状态和数据的打印方便分析。
uvc_v4l2_set_streamparm
uvc_v4l2_try_format
uvc_probe_video
我这里在函数uvc_v4l2_try_format和uvc_probe_video中增加打印信息
static int uvc_v4l2_try_format(struct uvc_streaming *stream,struct v4l2_format *fmt, struct uvc_streaming_control *probe,struct uvc_format **uvc_format, struct uvc_frame **uvc_frame){struct uvc_format *format = NULL;struct uvc_frame *frame = NULL;u16 rw, rh;unsigned int d, maxd;unsigned int i;u32 interval;int ret = 0;u8 *fcc;if (fmt->type != stream->type)return -EINVAL;fcc = (u8 *)&fmt->fmt.pix.pixelformat;uvc_dbg(stream->dev, FORMAT, "Trying format 0x%08x (%c%c%c%c): %ux%u\n",fmt->fmt.pix.pixelformat,fcc[0], fcc[1], fcc[2], fcc[3],fmt->fmt.pix.width, fmt->fmt.pix.height);/* Check if the hardware supports the requested format, use the default* format otherwise.*/for (i = 0; i < stream->nformats; ++i) {format = &stream->format[i];if (format->fcc == fmt->fmt.pix.pixelformat)break;}if (i == stream->nformats) {format = stream->def_format;fmt->fmt.pix.pixelformat = format->fcc;}/* Find the closest image size. The distance between image sizes is* the size in pixels of the non-overlapping regions between the* requested size and the frame-specified size.*/rw = fmt->fmt.pix.width;rh = fmt->fmt.pix.height;maxd = (unsigned int)-1;for (i = 0; i < format->nframes; ++i) {u16 w = format->frame[i].wWidth;u16 h = format->frame[i].wHeight;d = min(w, rw) * min(h, rh);d = w*h + rw*rh - 2*d;if (d < maxd) {maxd = d;frame = &format->frame[i];}if (maxd == 0)break;}if (frame == NULL) {uvc_dbg(stream->dev, FORMAT, "Unsupported size %ux%u\n",fmt->fmt.pix.width, fmt->fmt.pix.height);return -EINVAL;}/* Use the default frame interval. */interval = frame->dwDefaultFrameInterval;uvc_dbg(stream->dev, FORMAT,"Using default frame interval %u.%u us (%u.%u fps)\n",interval / 10, interval % 10, 10000000 / interval,(100000000 / interval) % 10);/* Set the format index, frame index and frame interval. */memset(probe, 0, sizeof(*probe));probe->bmHint = 1; /* dwFrameInterval */probe->bFormatIndex = format->index;probe->bFrameIndex = frame->bFrameIndex;probe->dwFrameInterval = uvc_try_frame_interval(frame, interval);/* Some webcams stall the probe control set request when the* dwMaxVideoFrameSize field is set to zero. The UVC specification* clearly states that the field is read-only from the host, so this* is a webcam bug. Set dwMaxVideoFrameSize to the value reported by* the webcam to work around the problem.** The workaround could probably be enabled for all webcams, so the* quirk can be removed if needed. It's currently useful to detect* webcam bugs and fix them before they hit the market (providing* developers test their webcams with the Linux driver as well as with* the Windows driver).*/mutex_lock(&stream->mutex);if (stream->dev->quirks & UVC_QUIRK_PROBE_EXTRAFIELDS)probe->dwMaxVideoFrameSize =stream->ctrl.dwMaxVideoFrameSize;/* Probe the device. */ret = uvc_probe_video(stream, probe);mutex_unlock(&stream->mutex);if (ret < 0){uvc_dbg(stream->dev, FORMAT,"%s %d %d\r\n",__FILE__,__LINE__,ret);goto done;}/* After the probe, update fmt with the values returned from* negotiation with the device. Some devices return invalid bFormatIndex* and bFrameIndex values, in which case we can only assume they have* accepted the requested format as-is.*/uvc_dbg(stream->dev, FORMAT,"%s %d stream->nformats:%d\r\n",__FILE__,__LINE__,stream->nformats);for (i = 0; i < stream->nformats; ++i) {if (probe->bFormatIndex == stream->format[i].index) {format = &stream->format[i];uvc_dbg(stream->dev, FORMAT,"%s %d match format:%d\r\n",__FILE__,__LINE__,probe->bFormatIndex);break;}}if (i == stream->nformats)uvc_dbg(stream->dev, FORMAT,"Unknown bFormatIndex %u, using default\n",probe->bFormatIndex);uvc_dbg(stream->dev, FORMAT,"%s %d format->nframes:%d\r\n",__FILE__,__LINE__,format->nframes);for (i = 0; i < format->nframes; ++i) {if (probe->bFrameIndex == format->frame[i].bFrameIndex) {frame = &format->frame[i];uvc_dbg(stream->dev, FORMAT,"%s %d match frame:%d\r\n",__FILE__,__LINE__,probe->bFrameIndex);break;}}if (i == format->nframes)uvc_dbg(stream->dev, FORMAT,"Unknown bFrameIndex %u, using default\n",probe->bFrameIndex);fmt->fmt.pix.width = frame->wWidth;fmt->fmt.pix.height = frame->wHeight;fmt->fmt.pix.field = V4L2_FIELD_NONE;fmt->fmt.pix.bytesperline = uvc_v4l2_get_bytesperline(format, frame);fmt->fmt.pix.sizeimage = probe->dwMaxVideoFrameSize;fmt->fmt.pix.pixelformat = format->fcc;fmt->fmt.pix.colorspace = format->colorspace;fmt->fmt.pix.xfer_func = format->xfer_func;fmt->fmt.pix.ycbcr_enc = format->ycbcr_enc;uvc_dbg(stream->dev, FORMAT,"%s %d width:%d,height:%d,field:%d,bytesperline:%d,sizeimage:%d,pixelformat:%d,colorspace:%d,xfer_func:%d,ycbcr_enc:%d\r\n",__FILE__,__LINE__,fmt->fmt.pix.width,fmt->fmt.pix.height,fmt->fmt.pix.field,fmt->fmt.pix.bytesperline,fmt->fmt.pix.sizeimage,fmt->fmt.pix.pixelformat,fmt->fmt.pix.colorspace,fmt->fmt.pix.xfer_func,fmt->fmt.pix.ycbcr_enc);if (uvc_format != NULL){*uvc_format = format;uvc_dbg(stream->dev, FORMAT, "set uvc_format\r\n");}if (uvc_frame != NULL){*uvc_frame = frame;uvc_dbg(stream->dev, FORMAT, "set uvc_frame\r\n");}done:return ret;}int uvc_probe_video(struct uvc_streaming *stream,struct uvc_streaming_control *probe){struct uvc_streaming_control probe_min, probe_max;u16 bandwidth;unsigned int i;int ret;/* Perform probing. The device should adjust the requested values* according to its capabilities. However, some devices, namely the* first generation UVC Logitech webcams, don't implement the Video* Probe control properly, and just return the needed bandwidth. For* that reason, if the needed bandwidth exceeds the maximum available* bandwidth, try to lower the quality.*/ret = uvc_set_video_ctrl(stream, probe, 1);if (ret < 0){uvc_dbg(stream->dev, FORMAT,"%s %d %d\r\n",__FILE__,__LINE__,ret);goto done;}/* Get the minimum and maximum values for compression settings. */uvc_dbg(stream->dev, FORMAT,"%s %d stream->dev->quirks:%x\r\n",__FILE__,__LINE__,stream->dev->quirks);if (!(stream->dev->quirks & UVC_QUIRK_PROBE_MINMAX)) {ret = uvc_get_video_ctrl(stream, &probe_min, 1, UVC_GET_MIN);if (ret < 0){uvc_dbg(stream->dev, FORMAT,"%s %d %d\r\n",__FILE__,__LINE__,ret);goto done;}ret = uvc_get_video_ctrl(stream, &probe_max, 1, UVC_GET_MAX);if (ret < 0){uvc_dbg(stream->dev, FORMAT,"%s %d %d\r\n",__FILE__,__LINE__,ret);goto done;}probe->wCompQuality = probe_max.wCompQuality;uvc_dbg(stream->dev, FORMAT,"%s %d probe->wCompQuality:%x\r\n",__FILE__,__LINE__,probe->wCompQuality);}for (i = 0; i < 2; ++i) {ret = uvc_set_video_ctrl(stream, probe, 1);if (ret < 0){uvc_dbg(stream->dev, FORMAT,"%s %d %d\r\n",__FILE__,__LINE__,ret);goto done;}ret = uvc_get_video_ctrl(stream, probe, 1, UVC_GET_CUR);if (ret < 0){uvc_dbg(stream->dev, FORMAT,"%s %d %d\r\n",__FILE__,__LINE__,ret);goto done;}uvc_dbg(stream->dev, FORMAT,"%s %d pstream->intf->num_altsetting:%x\r\n",__FILE__,__LINE__,stream->intf->num_altsetting);if (stream->intf->num_altsetting == 1)break;bandwidth = probe->dwMaxPayloadTransferSize;uvc_dbg(stream->dev, FORMAT,"%s %d bandwidth:%x\r\n",__FILE__,__LINE__,bandwidth);if (bandwidth <= stream->maxpsize)break;if (stream->dev->quirks & UVC_QUIRK_PROBE_MINMAX) {ret = -ENOSPC;goto done;}/* TODO: negotiate compression parameters */probe->wKeyFrameRate = probe_min.wKeyFrameRate;probe->wPFrameRate = probe_min.wPFrameRate;probe->wCompQuality = probe_max.wCompQuality;probe->wCompWindowSize = probe_min.wCompWindowSize;uvc_dbg(stream->dev, FORMAT,"%s %d probe->wKeyFrameRate:%x\r\n",__FILE__,__LINE__,probe->wKeyFrameRate);uvc_dbg(stream->dev, FORMAT,"%s %d probe->wPFrameRate:%x\r\n",__FILE__,__LINE__,probe->wPFrameRate);uvc_dbg(stream->dev, FORMAT,"%s %d probe->wCompQuality:%x\r\n",__FILE__,__LINE__,probe->wCompQuality);uvc_dbg(stream->dev, FORMAT,"%s %d probe->wCompWindowSize:%x\r\n",__FILE__,__LINE__,probe->wCompWindowSize);}done:return ret;}
先使能UVC的dbg信息
sudo su
echo 0x01FFF > /sys/module/uvcvideo/parameters/trace
cat /sys/module/uvcvideo/parameters/trace
su qinyunti
然后清除dmesg
sudo dmesg -c
确认清除
dmesg
usbipd bind -b 3-2
usbipd attach -w -b 3-2之后
查看dmesg
[ 93.764118] vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(3)[ 93.764805] vhci_hcd vhci_hcd.0: devid(196610) speed(3) speed_str(high-speed)[ 93.765632] vhci_hcd vhci_hcd.0: Device attached[ 94.120776] usb 1-1: new high-speed USB device number 2 using vhci_hcd[ 94.270769] usb 1-1: SetAddress Request (2) to port 0[ 94.306545] usb 1-1: New USB device found, idVendor=1993, idProduct=0101, bcdDevice= 1.01[ 94.307540] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0[ 94.308758] usb 1-1: Product: .UVC[ 94.309224] usb 1-1: Manufacturer: .Technology[ 94.312458] usb 1-1: Probing generic UVC device 1[ 94.314366] usb 1-1: Found format NV12 little-endian (0x3231564e)[ 94.315230] usb 1-1: - 1280x720 (39.0 fps)[ 94.315614] usb 1-1: Found format H264 little-endian (0x34363248)[ 94.316145] usb 1-1: - 1280x720 (39.0 fps)[ 94.316444] usb 1-1: Found format MJPG little-endian (0x47504a4d)[ 94.316947] usb 1-1: - 1280x720 (39.0 fps)[ 94.317194] usb 1-1: Found UVC 1.10 device .UVC (1993:0101)[ 94.317582] usb 1-1: Scanning UVC chain:[ 94.317812] OT 3 <- PU 2 <- IT 1[ 94.318047] usb 1-1: Found a valid video chain (1 -> 3)[ 94.323796] usb 1-1: UVC device initialized[ 94.324422] usb 1-1: Probing generic UVC device 1[ 94.326098] usb 1-1: Found format NV12 little-endian (0x3231564e)[ 94.326771] usb 1-1: - 1280x720 (39.0 fps)[ 94.327083] usb 1-1: Found format H264 little-endian (0x34363248)[ 94.327581] usb 1-1: - 1280x720 (39.0 fps)[ 94.327998] usb 1-1: Found format MJPG little-endian (0x47504a4d)[ 94.328650] usb 1-1: - 1280x720 (39.0 fps)[ 94.328955] usb 1-1: Found UVC 1.10 device .UVC (1993:0101)[ 94.329397] usb 1-1: Scanning UVC chain:[ 94.329617] OT 6 <- PU 5 <- IT 4[ 94.329836] usb 1-1: Found a valid video chain (4 -> 6)[ 94.334657] usb 1-1: UVC device initialized
设备的串口打印
ITF:1 ID:0 GET CS:1 REQ:87 B:281802d0 OF:216 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:3,frame:101 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00uvc set itf 3 0,active_itf:0ITF:3 ID:0 GET CS:1 REQ:87 B:281803cc OF:216 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:3 ID:0 SET CS:1 REQ:1 B:281803cc OF:0 LEN:34probe format:3,frame:101 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:3 ID:0 GET CS:1 REQ:81 B:281803cc OF:0 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00
运行
sudo guvcview
查看dmesg
[ 201.207930] usb 1-1: uvc_v4l2_open[ 201.210377] usb 1-1: uvc_v4l2_release[ 201.212104] usb 1-1: uvc_v4l2_open[ 201.213039] usb 1-1: uvc_v4l2_release[ 201.215030] usb 1-1: uvc_v4l2_open[ 201.216886] usb 1-1: Control 0x00980900 not found[ 201.217702] usb 1-1: Control 0x00980901 not found[ 201.218261] usb 1-1: Control 0x00980902 not found[ 201.218770] usb 1-1: Control 0x00980903 not found[ 201.219250] usb 1-1: Control 0x00980904 not found[ 201.219726] usb 1-1: Control 0x00980905 not found[ 201.220225] usb 1-1: Control 0x00980906 not found[ 201.220745] usb 1-1: Control 0x00980907 not found[ 201.221266] usb 1-1: Control 0x00980908 not found[ 201.221701] usb 1-1: Control 0x00980909 not found[ 201.222089] usb 1-1: Control 0x0098090a not found[ 201.222467] usb 1-1: Control 0x0098090b not found[ 201.222827] usb 1-1: Control 0x0098090c not found[ 201.223221] usb 1-1: Control 0x0098090d not found[ 201.223588] usb 1-1: Control 0x0098090e not found[ 201.223973] usb 1-1: Control 0x0098090f not found[ 201.224394] usb 1-1: Control 0x00980910 not found[ 201.224778] usb 1-1: Control 0x00980911 not found[ 201.225139] usb 1-1: Control 0x00980912 not found[ 201.225478] usb 1-1: Control 0x00980913 not found[ 201.225824] usb 1-1: Control 0x00980914 not found[ 201.226177] usb 1-1: Control 0x00980915 not found[ 201.226549] usb 1-1: Control 0x00980916 not found[ 201.226929] usb 1-1: Control 0x00980917 not found[ 201.227379] usb 1-1: Control 0x00980918 not found[ 201.227785] usb 1-1: Control 0x00980919 not found[ 201.228152] usb 1-1: Control 0x0098091a not found[ 201.228523] usb 1-1: Control 0x0098091b not found[ 201.229016] usb 1-1: Control 0x0098091c not found[ 201.229670] usb 1-1: Control 0x0098091d not found[ 201.230266] usb 1-1: Control 0x0098091e not found[ 201.231027] usb 1-1: Control 0x0098091f not found[ 201.231680] usb 1-1: Control 0x00980920 not found[ 201.232314] usb 1-1: Control 0x00980921 not found[ 201.232860] usb 1-1: Control 0x00980922 not found[ 201.233365] usb 1-1: Control 0x00980923 not found[ 201.234030] usb 1-1: Control 0x00980924 not found[ 201.234480] usb 1-1: Control 0x00980925 not found[ 201.234925] usb 1-1: Control 0x00980926 not found[ 201.235382] usb 1-1: Control 0x00980927 not found[ 201.235820] usb 1-1: Control 0x00980928 not found[ 201.236251] usb 1-1: Control 0x00980929 not found[ 201.236697] usb 1-1: Control 0x0098092a not found[ 201.237144] usb 1-1: Control 0x009a0900 not found[ 201.237609] usb 1-1: Control 0x009a0901 not found[ 201.238100] usb 1-1: Control 0x009a0902 not found[ 201.238452] usb 1-1: Control 0x009a0903 not found[ 201.238796] usb 1-1: Control 0x009a0904 not found[ 201.239199] usb 1-1: Control 0x009a0905 not found[ 201.239802] usb 1-1: Control 0x009a0906 not found[ 201.240136] usb 1-1: Control 0x009a0907 not found[ 201.240470] usb 1-1: Control 0x009a0908 not found[ 201.240846] usb 1-1: Control 0x009a0909 not found[ 201.241240] usb 1-1: Control 0x009a090a not found[ 201.241628] usb 1-1: Control 0x009a090b not found[ 201.242255] usb 1-1: Control 0x009a090c not found[ 201.242884] usb 1-1: Control 0x009a090d not found[ 201.243589] usb 1-1: Control 0x009a090e not found[ 201.244387] usb 1-1: Control 0x009a090f not found[ 201.245005] usb 1-1: Control 0x009a0910 not found[ 201.245797] usb 1-1: Control 0x009a0911 not found[ 201.246278] usb 1-1: Control 0x009a0912 not found[ 201.246899] usb 1-1: Control 0x009a0913 not found[ 201.247883] usb 1-1: Control 0x009a0914 not found[ 201.248643] usb 1-1: Control 0x009a0915 not found[ 201.249343] usb 1-1: Control 0x009a0916 not found[ 201.249885] usb 1-1: Control 0x009a0917 not found[ 201.250389] usb 1-1: Control 0x009a0918 not found[ 201.250938] usb 1-1: Control 0x009a0919 not found[ 201.251443] usb 1-1: Control 0x009a091a not found[ 201.251968] usb 1-1: Control 0x009a091b not found[ 201.252459] usb 1-1: Control 0x009a091c not found[ 201.252964] usb 1-1: Control 0x009a091d not found[ 201.253356] usb 1-1: Control 0x009a091e not found[ 201.253736] usb 1-1: Control 0x009a091f not found[ 201.254114] usb 1-1: Control 0x08000000 not found[ 201.277422] usb 1-1: Trying format 0x47504a4d (MJPG): 1280x720[ 201.278244] usb 1-1: Using default frame interval 25641.0 us (39.0 fps)[ 201.280293] usb 1-1: drivers/media/usb/uvc/uvc_video.c 404 stream->dev->quirks:0[ 201.284240] usb 1-1: drivers/media/usb/uvc/uvc_video.c 417 probe->wCompQuality:0[ 201.287658] usb 1-1: drivers/media/usb/uvc/uvc_video.c 431 pstream->intf->num_altsetting:2[ 201.288450] usb 1-1: drivers/media/usb/uvc/uvc_video.c 436 bandwidth:0[ 201.288956] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 266 stream->nformats:3[ 201.289574] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 270 match format:3[ 201.290880] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 280 format->nframes:1[ 201.291957] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 284 match frame:1[ 201.292698] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 304 width:1280,height:720,field:1,bytesperline:0,sizeimage:0,pixelformat:1196444237,colorspace:0,xfer_func:0,ycbcr_enc:0[ 201.294226] usb 1-1: Trying format 0x47504a4d (MJPG): 1280x720[ 201.294850] usb 1-1: Using default frame interval 25641.0 us (39.0 fps)[ 201.296655] usb 1-1: drivers/media/usb/uvc/uvc_video.c 404 stream->dev->quirks:0[ 201.300138] usb 1-1: drivers/media/usb/uvc/uvc_video.c 417 probe->wCompQuality:0[ 201.303232] usb 1-1: drivers/media/usb/uvc/uvc_video.c 431 pstream->intf->num_altsetting:2[ 201.304038] usb 1-1: drivers/media/usb/uvc/uvc_video.c 436 bandwidth:0[ 201.304572] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 266 stream->nformats:3[ 201.305211] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 270 match format:3[ 201.306009] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 280 format->nframes:1[ 201.306951] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 284 match frame:1[ 201.307689] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 304 width:1280,height:720,field:1,bytesperline:0,sizeimage:0,pixelformat:1196444237,colorspace:0,xfer_func:0,ycbcr_enc:0[ 201.309043] usb 1-1: set uvc_format[ 201.309393] usb 1-1: set uvc_frame[ 201.317452] ------------[ cut here ]------------[ 201.318141] WARNING: CPU: 0 PID: 314 at drivers/media/common/videobuf2/videobuf2-core.c:815 vb2_core_reqbufs+0x141/0x3a0[ 201.319212] Modules linked in:[ 201.319551] CPU: 0 PID: 314 Comm: guvcview Not tainted 5.15.167.4-microsoft-standard-WSL2 #3[ 201.320344] RIP: 0010:vb2_core_reqbufs+0x141/0x3a0[ 201.320853] Code: 85 c9 0f 84 29 02 00 00 8d 51 ff 48 8d 44 24 08 48 8d 54 94 0c eb 0d 48 83 c0 04 48 39 d0 0f 84 fe 00 00 00 8b 30 85 f6 75 ed <0f> 0b 41 bf ea ff ff ff 4c 89 e7 e8 9f 0b 49 00 4c 89 e7 c7 85 c8[ 201.322443] RSP: 0018:ffffc90005c83cb8 EFLAGS: 00010246[ 201.322896] RAX: ffffc90005c83cc0 RBX: ffffc90005c83e48 RCX: 0000000000000001[ 201.323721] RDX: ffffc90005c83cc4 RSI: 0000000000000000 RDI: ffff888103d38518[ 201.324471] RBP: ffff888103d38518 R08: 0000000000000000 R09: 0000000000000000[ 201.325168] R10: 0000000000000000 R11: ffffffff825073e0 R12: ffff888103d385c0[ 201.325884] R13: 0000000000000001 R14: ffff888103d38580 R15: 0000000000000000[ 201.326597] FS: 00007fdf6cbbae80(0000) GS:ffff8881dc600000(0000) knlGS:0000000000000000[ 201.327312] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033[ 201.327896] CR2: 00007fdf6c914000 CR3: 0000000102436000 CR4: 00000000003506b0[ 201.328644] Call Trace:[ 201.328941] <TASK>[ 201.329197] ? __warn+0x80/0x100[ 201.329498] ? vb2_core_reqbufs+0x141/0x3a0[ 201.329784] ? report_bug+0x9e/0xc0[ 201.330069] ? handle_bug+0x3c/0x70[ 201.330411] ? exc_invalid_op+0x14/0x70[ 201.330884] ? asm_exc_invalid_op+0x16/0x20[ 201.331230] ? vb2_core_reqbufs+0x141/0x3a0[ 201.331569] ? vb2_core_reqbufs+0x10c/0x3a0[ 201.331970] uvc_request_buffers+0x29/0x50[ 201.332348] uvc_ioctl_reqbufs+0x46/0xa0[ 201.332755] ? v4l_reqbufs+0x22/0x60[ 201.333135] __video_do_ioctl+0x3a0/0x3e0[ 201.333470] ? srso_return_thunk+0x5/0x10[ 201.333746] ? page_add_new_anon_rmap+0x4e/0xf0[ 201.334123] video_usercopy+0x2e1/0x760[ 201.334492] ? v4l_print_control+0x20/0x20[ 201.334813] ? srso_return_thunk+0x5/0x10[ 201.335138] v4l2_ioctl+0x49/0x50[ 201.335458] __x64_sys_ioctl+0x8a/0xc0[ 201.335826] do_syscall_64+0x35/0xb0[ 201.336346] entry_SYSCALL_64_after_hwframe+0x6c/0xd6[ 201.336913] RIP: 0033:0x7fdf75fff88d[ 201.337319] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 73 b5 0f 00 f7 d8 64 89 01 48[ 201.339122] RSP: 002b:00007fff1e1e6228 EFLAGS: 00000246 ORIG_RAX: 0000000000000010[ 201.340090] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fdf75fff88d[ 201.340851] RDX: 000056188e4826c0 RSI: 00000000c0145608 RDI: 0000000000000004[ 201.341590] RBP: 00000000c0145608 R08: 0000000000000000 R09: 0000000000000000[ 201.342302] R10: 00007fdf75edd020 R11: 0000000000000246 R12: 0000000000000004[ 201.342997] R13: 0000000000000000 R14: 00007fdf75edd020 R15: 000056188e4826c0[ 201.343714] TASK>[ 201.343945] ---[ end trace ad1f2ae766fc9251 ]---[ 201.344584] usb 1-1: Trying format 0x3231564e (NV12): 1280x720[ 201.345253] usb 1-1: Using default frame interval 25641.0 us (39.0 fps)[ 201.346991] usb 1-1: drivers/media/usb/uvc/uvc_video.c 404 stream->dev->quirks:0[ 201.350002] usb 1-1: drivers/media/usb/uvc/uvc_video.c 417 probe->wCompQuality:0[ 201.353228] usb 1-1: drivers/media/usb/uvc/uvc_video.c 431 pstream->intf->num_altsetting:2[ 201.354172] usb 1-1: drivers/media/usb/uvc/uvc_video.c 436 bandwidth:0[ 201.354830] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 266 stream->nformats:3[ 201.355624] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 270 match format:1[ 201.356352] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 280 format->nframes:1[ 201.357123] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 284 match frame:1[ 201.357714] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 304 width:1280,height:720,field:1,bytesperline:1280,sizeimage:1382400,pixelformat:842094158,colorspace:8,xfer_func:1,ycbcr_enc:1[ 201.359176] usb 1-1: Trying format 0x3231564e (NV12): 1280x720[ 201.359782] usb 1-1: Using default frame interval 25641.0 us (39.0 fps)[ 201.361507] usb 1-1: drivers/media/usb/uvc/uvc_video.c 404 stream->dev->quirks:0[ 201.364710] usb 1-1: drivers/media/usb/uvc/uvc_video.c 417 probe->wCompQuality:0[ 201.368030] usb 1-1: drivers/media/usb/uvc/uvc_video.c 431 pstream->intf->num_altsetting:2[ 201.368993] usb 1-1: drivers/media/usb/uvc/uvc_video.c 436 bandwidth:0[ 201.369637] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 266 stream->nformats:3[ 201.370419] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 270 match format:1[ 201.371077] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 280 format->nframes:1[ 201.371718] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 284 match frame:1[ 201.372273] usb 1-1: drivers/media/usb/uvc/uvc_v4l2.c 304 width:1280,height:720,field:1,bytesperline:1280,sizeimage:1382400,pixelformat:842094158,colorspace:8,xfer_func:1,ycbcr_enc:1[ 201.373622] usb 1-1: set uvc_format[ 201.373912] usb 1-1: set uvc_frame[ 201.378054] usb 1-1: uvc_v4l2_mmap[ 201.378682] usb 1-1: uvc_v4l2_mmap[ 201.379126] usb 1-1: uvc_v4l2_mmap[ 201.379550] usb 1-1: uvc_v4l2_mmap[ 201.379974] usb 1-1: Setting frame interval to 1/25 (400000)[ 201.381805] usb 1-1: drivers/media/usb/uvc/uvc_video.c 404 stream->dev->quirks:0[ 201.385213] usb 1-1: drivers/media/usb/uvc/uvc_video.c 417 probe->wCompQuality:0[ 201.388137] usb 1-1: drivers/media/usb/uvc/uvc_video.c 431 pstream->intf->num_altsetting:2[ 201.389009] usb 1-1: drivers/media/usb/uvc/uvc_video.c 436 bandwidth:0[ 201.497158] misc dxg: dxgk: dxgkio_is_feature_enabled: Ioctl failed: -22[ 201.500618] misc dxg: dxgk: dxgkio_query_adapter_info: Ioctl failed: -22[ 201.501538] misc dxg: dxgk: dxgkio_query_adapter_info: Ioctl failed: -22[ 201.502355] misc dxg: dxgk: dxgkio_query_adapter_info: Ioctl failed: -22[ 201.503101] misc dxg: dxgk: dxgkio_query_adapter_info: Ioctl failed: -22[ 201.503963] misc dxg: dxgk: dxgkio_query_adapter_info: Ioctl failed: -2[ 201.670572] usb 1-1: Device requested null bandwidth, defaulting to lowest[ 201.671624] usb 1-1: Selecting alternate setting 1 (1024 B/frame bandwidth)[ 201.676945] usb 1-1: Allocated 5 URB buffers of 32x1024 bytes each[ 201.678552] usb 1-1: uvc_v4l2_poll[ 201.836093] usb 1-1: Frame complete (EOF found)[ 201.995351] usb 1-1: frame 1 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 202.027253] usb 1-1: Frame complete (EOF found)[ 202.187363] usb 1-1: frame 2 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 202.188630] usb 1-1: Frame complete (EOF found)[ 202.347510] usb 1-1: frame 3 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 202.379318] usb 1-1: Frame complete (EOF found)[ 202.539504] usb 1-1: frame 4 stats: 0/22/22 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 202.541300] usb 1-1: Frame complete (EOF found)[ 202.679618] usb 1-1: uvc_v4l2_poll[ 202.681203] vhci_hcd: unlink->seqnum 82[ 202.682047] vhci_hcd: urb->status -104[ 202.683629] vhci_hcd: unlink->seqnum 83[ 202.684305] vhci_hcd: urb->status -104[ 202.685409] vhci_hcd: unlink->seqnum 84[ 202.686028] vhci_hcd: urb->status -104[ 202.687147] vhci_hcd: unlink->seqnum 85[ 202.687768] vhci_hcd: urb->status -104[ 202.690592] vhci_hcd: unlink->seqnum 86[ 202.691222] vhci_hcd: urb->status -104[ 202.697097] usb 1-1: Setting frame interval to 1/39 (256410)[ 202.699608] usb 1-1: drivers/media/usb/uvc/uvc_video.c 404 stream->dev->quirks:0[ 202.702845] usb 1-1: drivers/media/usb/uvc/uvc_video.c 417 probe->wCompQuality:0[ 202.706362] usb 1-1: drivers/media/usb/uvc/uvc_video.c 431 pstream->intf->num_altsetting:2[ 202.707301] usb 1-1: drivers/media/usb/uvc/uvc_video.c 436 bandwidth:0[ 202.707997] usb 1-1: uvc_v4l2_mmap[ 202.708448] usb 1-1: uvc_v4l2_mmap[ 202.708839] usb 1-1: uvc_v4l2_mmap[ 202.709265] usb 1-1: uvc_v4l2_mmap[ 202.710815] usb 1-1: Device requested null bandwidth, defaulting to lowest[ 202.711466] usb 1-1: Selecting alternate setting 1 (1024 B/frame bandwidth)[ 202.716751] usb 1-1: Allocated 5 URB buffers of 32x1024 bytes each[ 202.717703] usb 1-1: uvc_v4l2_poll[ 202.745431] usb 1-1: Frame complete (EOF found)[ 202.905409] usb 1-1: frame 1 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 202.937378] usb 1-1: Frame complete (EOF found)[ 203.097862] usb 1-1: frame 2 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 203.099538] usb 1-1: Frame complete (EOF found)[ 203.257478] usb 1-1: frame 3 stats: 0/22/22 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 203.289444] usb 1-1: Frame complete (EOF found)[ 203.449523] usb 1-1: frame 4 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 203.451155] usb 1-1: Frame complete (EOF found)[ 203.609555] usb 1-1: frame 5 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 203.641387] usb 1-1: Frame complete (EOF found)[ 203.718912] usb 1-1: uvc_v4l2_poll[ 203.719763] usb 1-1: uvc_v4l2_poll[ 203.801564] usb 1-1: frame 6 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 203.803195] usb 1-1: Frame complete (EOF found)[ 203.961536] usb 1-1: frame 7 stats: 0/22/22 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 203.993402] usb 1-1: Frame complete (EOF found)[ 204.153744] usb 1-1: frame 8 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 204.156312] usb 1-1: Frame complete (EOF found)[ 204.313624] usb 1-1: frame 9 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 204.345445] usb 1-1: Frame complete (EOF found)[ 204.505525] usb 1-1: frame 10 stats: 0/23/23 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 204.506837] usb 1-1: Frame complete (EOF found)[ 204.665466] usb 1-1: frame 11 stats: 0/22/22 packets, 0/0/0 pts (!early !initial), 0/0 scr, last pts/stc/sof 0/0/0[ 204.697380] usb 1-1: Frame complete (EOF found)[ 204.720845] usb 1-1: uvc_v4l2_poll[ 204.722161] vhci_hcd: unlink->seqnum 162[ 204.722797] vhci_hcd: urb->status -104[ 204.724195] vhci_hcd: unlink->seqnum 163[ 204.724792] vhci_hcd: urb->status -104[ 204.725940] vhci_hcd: unlink->seqnum 164[ 204.726487] vhci_hcd: urb->status -104[ 204.727479] vhci_hcd: unlink->seqnum 165[ 204.728023] vhci_hcd: urb->status -104[ 204.729319] vhci_hcd: unlink->seqnum 166[ 204.729871] vhci_hcd: urb->status -104[ 204.742738] usb 1-1: uvc_v4l2_releaseqinyunti:~$
此时串口打印
sh>ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:3,frame:101 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:3401 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:3,frame:101 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:3,frame:101 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:3401 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:3,frame:101 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:3401 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:3401 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:3401 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 SET CS:2 REQ:1 B:281800d8 OF:0 LEN:34commit format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00uvc set itf 1 1,active_itf:1dev:0,itf:1,format:1,frame:1mjpeg 0 used:8424(uS) len:22567dev:0,itf:1,format:1,frame:1mjpeg 0 used:8419(uS) len:22613dev:0,itf:1,format:1,frame:1mjpeg 0 used:8418(uS) len:22054dev:0,itf:1,format:1,frame:1mjpeg 0 used:8421(uS) len:23084dev:0,itf:1,format:1,frame:1mjpeg 0 used:8421(uS) len:22819dev:0,itf:1,format:1,frame:1mjpeg 0 used:8422(uS) len:22746uvc set itf 1 0,active_itf:0ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:3401 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:3401 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34probe format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:3401 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00ITF:1 ID:0 SET CS:2 REQ:1 B:281800d8 OF:0 LEN:34commit format:1,frame:101 00 01 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 18 15 00 00 00 00 00 00 00 00 00 00 00 00 00uvc set itf 1 1,active_itf:1dev:0,itf:1,format:1,frame:1mjpeg 0 used:8420(uS) len:21833dev:0,itf:1,format:1,frame:1
对照可以看到dwMaxPayloadTransferSize为0，而该值从GET_CUR
前面的ret = uvc_get_video_ctrl(stream, probe, 1, UVC_GET_CUR);获取
即设备返回的34字节的偏移22字节处的值
ctrl->dwMaxPayloadTransferSize = get_unaligned_le32(&data[22]);
从打印看HOST SET_CUR发送的值是，这部分填写0，device的逻辑是收到SET_CUR后覆盖，GET_CUR时返回的是上一次的值。
ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34
probe format:3,frame:1
01 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ITF:1 ID:0 GET CS:1 REQ:82 B:281802d0 OF:36 LEN:34
01 00 01 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00
ITF:1 ID:0 GET CS:1 REQ:83 B:281802d0 OF:72 LEN:34
01 00 03 01 9a 19 03 00 00 00 00 00 00 00 00 00 00 00 00 c0 3f 00 ff 03 00 00 80 c3 c9 01 03 00 00 00
ITF:1 ID:0 SET CS:1 REQ:1 B:281802d0 OF:0 LEN:34
probe format:3,frame:1
01 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ITF:1 ID:0 GET CS:1 REQ:81 B:281802d0 OF:0 LEN:34
01 00 03 01 9a e9 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
这里device的逻辑有问题,需要修改下，
SET时只有非零值才会生效，才会覆盖CUR值，0值不覆盖原来的CUR值。
在UVC的规格书中其实也有类似的介绍。
修改了上述问题之后，再测试看到了打印如下信息
“Dropping payload (out of sync)”
我们查找对应的代码处
可以看到如下逻辑，看到fid一直不变才会有这个打印，那么基本就确认问题了
再去看设备那边的代码，确实是多设备使用了同一个fid记录，增加设备时忘记改这里了，导致一个设备tog fid，然后另一个设备又tog fid，最终看起来是fid没变。修改就很简单，各个设备使用各自的fid记录就可以了。
以上实际也可以通过抓包查看发出的包是否FID FED正确也可以发现，分享以上，重点在于以上分析调试方法。打印相关信息会更加直观。
除了之前提的guvcview这里还推荐下qv4l2工具，在linux下进行uvc的查看。
sudo apt install v4l-utils
sudo apt install qv4l2
sudo qv4l2
这里双UVC设备显示如下
以上主要是分享基于WSL2如何修改内核UVC相关代码，增加调试信息去进行调试，问题本身不是很重要，重点是分享分析过程。而分享的案例本身的问题，一个是Probe Commit处理时对SET_CUR的处理不合理，将0值也进行了覆盖，一个是增加多设备支持时把负载头的FID共用了，没有区分开，导致一个设备发完一帧TOG了FID，下一个设备又发一帧又TOG了FID，两次TOG之后导致某一个设备的FID始终不变，windows下能够处理这种问题(这里发的是MJPEG猜测系统是根据负载头的FED位区分，或者是根据MPJEG本身头尾标志区分的)，linux下则无法区分帧，解决办法是多个设备各自使用自己的FID记录。这里也可以看出windows确实兼容性是做的很好的，考虑了很多容错处理，虽然这里是设备那边的问题，但是这种不是致命的问题windows能正常显示，linux则不能。
