On Tue, Oct 16, 2012 at 11:20:23AM -0400, Dave Jones wrote: > Gerry (CC'd) reported a bug to us that since 3.6.1, his illuminated > Logitech USB keyboard doesn't light up until he hits a key, and then > it immediately powers back off, defeating the purpose of having an > illumated keyboard.
Does he have the udev bug that turns on auto-suspend for USB keyboards? ISTR there was a Fedora bug that was fixed. I ask because it sounds like the keyboard is suspended between key strokes, and that powers down the light. The USB hid driver doesn't auto-suspend devices that have user toggleable LEDs. For instance, it won't suspend a keyboard if the caps lock or num lock key is set. But I'm betting the device doesn't advertise the backlight like the caps lock key is advertised. > Looking over the 3.6.1 changelog, I see this change, which sounds > like it might be responsible ? Did he actually do a git bisect? Because that commit only applies to when the system is suspended, not when the USB device is suspended. Sarah Sharp > commit ee537508bdc0c00b96ac497f3d82a68f820e6182 > Author: Michael Spang <sp...@chromium.org> > Date: Fri Sep 14 13:05:49 2012 -0400 > > Increase XHCI suspend timeout to 16ms > > commit a6e097dfdfd189b6929af6efa1d289af61858386 upstream. > > The Intel XHCI specification says that after clearing the run/stop bit > the controller may take up to 16ms to halt. We've seen a device take > 14ms, which with the current timeout of 10ms causes the kernel to > abort the suspend. Increasing the timeout to the recommended value > fixes the problem. > > This patch should be backported to kernels as old as 2.6.37, that > contain the commit 5535b1d5f8885695c6ded783c692e3c0d0eda8ca "USB: xHCI: > PCI power management implementation". > > Signed-off-by: Michael Spang <sp...@chromium.org> > Signed-off-by: Sarah Sharp <sarah.a.sh...@linux.intel.com> > Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> > > > Any thoughts on how we could prevent this generically, or is this > something we're going to have to quirk around for specific devices we > don't want to power down ? > > Dave > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
