/drivers/media/video/uvc/uvcvideo.c


/drivers/media/video/uvc/uvc_ctrl.c

line 789:

case VIDIOC_S_FMT:
  {
    800                 struct uvc_streaming_control probe;
    801
    802                 return uvc_v4l2_try_format(stream, arg, &probe, NULL, NULL);
    803         }

加了一些printk... 然後按下 dmesg...  得到這個訊息

 uvcvideo: Failed to set UVC probe control : -110 (exp. 26).

google  uvcvideo: Failed to set UVC probe control : -110 (exp. 26).

這是因為  uvc_v4l2_try_format() 裡面的

 ret = uvc_probe_video(stream, probe);

uvc_video.c  line  300

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)
                 goto done;

然後再呼叫  ret = uvc_set_video_ctrl(stream, probe, 1);

uvc_video.c  line 254 

static int uvc_set_video_ctrl(struct uvc_streaming *stream,
         struct uvc_streaming_control *ctrl, int probe)
 {
         __u8 *data;
         __u16 size;
         int ret;
 
         size = stream->dev->uvc_version >= 0x0110 ? 34 : 26;
         data = kzalloc(size, GFP_KERNEL);
         if (data == NULL)
                 return -ENOMEM;
 
         *(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
         data[2] = ctrl->bFormatIndex;
         data[3] = ctrl->bFrameIndex;
         *(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
         *(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
         *(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
         *(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
         *(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
         *(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
         put_unaligned_le32(ctrl->dwMaxVideoFrameSize, &data[18]);
         put_unaligned_le32(ctrl->dwMaxPayloadTransferSize, &data[22]);
 
         if (size == 34) {
                 put_unaligned_le32(ctrl->dwClockFrequency, &data[26]);
                 data[30] = ctrl->bmFramingInfo;
                 data[31] = ctrl->bPreferedVersion;
                 data[32] = ctrl->bMinVersion;
                 data[33] = ctrl->bMaxVersion;
         }
 
         ret = __uvc_query_ctrl(stream->dev, UVC_SET_CUR, 0, stream->intfnum,
                 probe ? UVC_VS_PROBE_CONTROL : UVC_VS_COMMIT_CONTROL, data,
                 size, uvc_timeout_param);
         if (ret != size) {
                 uvc_printk(KERN_ERR, "Failed to set UVC %s control : "
                         "%d (exp. %u).\n", probe ? "probe" : "commit",
                         ret, size);
                 ret = -EIO;
         }
 
         kfree(data);
         return ret;
 }

就發出 error message....

Ref : https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1018020

Logitech webcam not working

苦主的linux 版本是

Uname: Linux 3.5.0-1-generic i686

Joseph Salisbury (jsalisbury) wrote on 2012-06-26: 回說

Can you test the latest mainline kernel, to see if the bug is already fixed upstream? The latest mainline kernel is available at:
http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.5-rc4-quantal/

You will need to install both the linux-image and linux-image-extra .deb packages.

Thanks in advance!

Changed in linux (Ubuntu):
importance:	Undecided → Medium
tags:	added: kernel-da-key
Changed in linux (Ubuntu):
status:	New → Confirmed

目前的linux kernel 版本是  3.0.15

Linux localhost 3.0.15-Dmatek #202 SMP PREEMPT Fri Jul 1 13:28:07 CST 2016 armv7l GNU/Linux