Hello everybody, I'm currently having a bit of a struggle with a Logitech Quickcam 5000 Pro. I'm using a self-written library to access the camera in my computer vision software, and I have already accounted for the dreaded Logitech bug by disabling gain/exposure changes for now (or at least getting them down to an absolute minimum).
However, I'm still getting a different kind of error: after capturing some 100 frames, my VIDIOC_DQBUF ioctl will fail with -EIO. I'm using revision 84 with a small part of the patch from Evgeny (only the 500 us delay after control transfers). This comes from uvc_dequeue_buffer(..), with a trace message warning about corrupted data. Now, I have at times used an USB extension cable to connect the camera, and it seemed like the error happened more quickly then. So, is this really a problem of bad cabling? The syslog also seems to indicate this: Feb 5 14:03:24 atnavab12 kernel: usb 4-4: device descriptor read/64, error -110 Feb 5 14:03:27 atnavab12 kernel: ehci_hcd 0000:00:1d.7: port 4 reset error -110 Feb 5 14:03:27 atnavab12 kernel: hub 4-0:1.0: hub_port_status failed (err = -32) Feb 5 14:03:27 atnavab12 kernel: hub 4-0:1.0: Cannot enable port 4. Maybe the USB cable is bad? Feb 5 14:03:28 atnavab12 kernel: usb 4-4: new high speed USB device using ehci_hcd and address 115 Feb 5 14:03:30 atnavab12 kernel: usb 4-4: device descriptor read/8, error -71 Feb 5 14:03:30 atnavab12 kernel: usb 4-4: device descriptor read/8, error -71 Feb 5 14:03:30 atnavab12 kernel: usb 4-4: new high speed USB device using ehci_hcd and address 116 Feb 5 14:03:30 atnavab12 kernel: usb 4-4: device descriptor read/8, error -71 Feb 5 14:03:30 atnavab12 kernel: usb 4-4: device descriptor read/8, error -71 Are there any hints on how to avoid this? Should I try swapping the cable for one from another Logitech cam? Thanks in advance for your help, Yours, Florian
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