On Thu, 21 Jun 2012, Peter Chen wrote: > On Wed, Jun 20, 2012 at 10:20 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 19 Jun 2012, Philipp Dreimann wrote: > > > >> Hello, > >> > >> my usb webcam using the uvcvideo module is not working since kernel > >> 3.5-rc2. Kernel v3.4 is the last which is known to work, 3.5-rc3 is > >> broken too. > >> > >> The webcam does not work if it is connected to an usb2 port. If the > >> webcam is connected to an usb3 port it works. I compiled the uvcvideo > >> module from kernel 3.4 together with 3.5-rc3 to rule out the driver. > >> -- The behaviour did not change. (Thanks to Laurent Pinchart for the > >> idea.) > >> > >> Here is a log using usb3: > >> [ 1528.629506] usb 3-1: new high-speed USB device number 4 using xhci_hcd > >> [ 1529.364396] uvcvideo: Found UVC 1.00 device <unnamed> (046d:0821) > >> [ 1529.378344] input: UVC Camera (046d:0821) as > >> /devices/pci0000:00/0000:00:1c.6/0000:0e:00.0/usb3/3-1/3-1:1.2/input/input16 > >> -- Verifying whether the camera works -- successful. > >> [ 1571.789894] usb 3-1: USB disconnect, device number 4 > >> > >> > >> And the problematic one using usb2: > >> [ 1636.434459] usb 2-1.2: new high-speed USB device number 4 using ehci_hcd > >> [ 1637.237109] uvcvideo: Found UVC 1.00 device <unnamed> (046d:0821) > >> [ 1637.250484] input: UVC Camera (046d:0821) as > >> /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.2/input/input17 > >> -- Verifying whether the camera works -- not successful. > >> [ 1645.536061] uvcvideo: Failed to query (GET_DEF) UVC control 2 on > >> unit 2: -71 (exp. 2). > >> [ 1645.540292] uvcvideo: Failed to query (GET_DEF) UVC control 2 on > >> unit 2: -71 (exp. 2). > > > >> The last line is being repeated a lot, the Failed to query lines > >> appear every now and then.. > > > > -71 errors generally are caused by bad hardware. �In this case, it may > > be a bad cable connection between the device and the EHCI controller. > > That would explain why the same device works okay when connected to > > xHCI. > > > But the ep0 enumeration is ok, v3.4 is workable, and another uvc camera is ok. > So I think there are two possible reasons: > - USB2 ISO transfer handling changes > - UVC code changes Comparison of usbmon traces for the working and non-working cases might help point out any important difference. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
