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. > 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. 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. 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
