On Tue, 11 Nov 2008, Andi Kleen wrote: > On Mon, Nov 10, 2008 at 07:45:28PM -0500, Alan Stern wrote: > > On Tue, 11 Nov 2008, Andi Kleen wrote: > > > > > Hi, > > > > > > I have a box here which has a couple of USB devices connected. > > > That includes several HID devices (keyboards, mouse) and a couple > > > of others including a USB powerswitch driven through a user space > > > program. > > > > > > Now what happened is that I changed some of the HID devices > > > around (moving from a direct port to a hub) and also moved > > > the USB power switch from one port to another. But after that > > > the power switch didn't work anymore, just giving a flood > > > of > > > > > > usb 2-2: usbfs: interface 0 claimed by usbhid while 'sispm' sets config #1 > > > > > > (sispm is the user space driver) > > > > > > Kernel is 2.6.28-rc3 > > > > This sounds like a userspace problem. The sispm program should unbind > > usbhid from interface 0 before trying to set the config. > > Can you please explain in layman's terms why usbhid does not > unbind itself when it detects the removal of a device? It does. The problem is on the other side: Your power switch presents itself as an HID device, so when it is _detected_ it binds to usbhid. On the other hand, your log contains an error message saying "couldn't find an input interrupt endpoint". That should have caused usbhid's probe to fail. Perhaps the failure occurred on interface 1, leaving usbhid still bound to interface 0. You can find out exactly which drivers are bound to which interfaces by looking at /proc/bus/usb/devices. (Depending on your distribution, you may first need to mount /proc/bus/usb as type usbfs.) > Why should sispm need to unbind someone else? The usbfs API does not allow user programs to set a device's configuration if any drivers are bound to the device. Therefore, if a program wants to set a config then it must unbind all the existing drivers first. This is a safety precaution against programs interfering with other drivers. Now in fact, sispm probably doesn't need to set the configuration at all. This is undoubtedly a holdover from a Windows version, because Windows does not set device configurations by default whereas Linus does. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
