Hi Alan, On Friday 06 July 2012 09:50:30 Alan Stern wrote: > On Fri, 6 Jul 2012, Alan Cox wrote: > > From: Eric Ding <ericding@xxxxxxxxxxxx> > > > > working if I turn it on (e.g., guvcview), then shut it off, wait a few > > seconds, and then turn it on again. From the second time onward, all I > > get is screen noise rather than the expected video images. > > > > I did a kernel bisection, which revealed the commit that caused the > > regression: > > > > commit e1620d591a75a10b15cf61dbf8243a0b7e6731a2 > > Author: Rafael J. Wysocki <rjw@xxxxxxx> > > Date: Fri Mar 18 19:55:36 2011 +0100 > > > > USB: Move runtime PM callbacks to usb_device_pm_ops > > Can you figure out exactly how that commit caused the problem? As far > as I can tell, it should not have made any difference to anything. That patch has already been pointed out as problematic: http://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg48624.html (CC'ing the relevant people) > > This patch turns on USB_QUIRK_RESET_RESUME for Logitech Quickcam Fusion > > This indirectly disables autosuspend for this webcam, incidentally > > matches the way that several other Logitech webcams are handled, and > > avoids adding a specific UVC_QUIRK for this problem. > > > > What's more, the camera now works even after a suspend/resume cycle. > > Instead of having all these quirk entries, would it perhaps be better > to change the uvcvideo driver? It could set the quirk flag every time > it encounters a Logitech camera. Sure, if you think that's a good idea, I can do that. I'm not sure whether all Logitech webcams require the quirk though. > The main disadvantage would be that the quirk wouldn't get set > immediately. A camera might be autosuspended before the driver could > bind to it, and then it might crash when resumed later. Still, I think > this could be handled. -- Regards, Laurent Pinchart -- 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
