On Wed, Mar 05, 2014 at 11:26:06AM -0500, Alan Stern wrote: > On Wed, 5 Mar 2014, Poulain, Loic wrote: > > > + function 'do_rebind_interface' is in charge of unbind and rebind the interfaces with the 'need_binfind' flag set. > > + However this method is only called in 'usb_resume_complete'. > > + Problem is that 'usb_resume_complete' is a dev_pm_ops callback (core/usb.h) used by the System PM core which is never called in a runtime PM scenario. > > + So interfaces remain suspended forever (or until the next PM system suspend/resume), device is unusable. > > (unbinding/rebinding manually the interface via sysfs recovers the device) > > > > Could you please let me know if it's the expected behavior or a real issue. Should we not call 'do_rebind_interface' in the runtime resume sequence? > > I suspect this is an oversight. > > Still, implementing it would be difficult. In usb_runtime_resume, the > device lock may or may not already be held. Therefore we cannot simply > lock the device and call do_rebind_interfaces. > > Using a work queue for this seems like overkill (and it seems fragile). > I don't know what we should do. > If the autosuspend supported device can't respond resume correctly, eg, after resume, it can't respond GET_STATUS correctly in this case, the .reset_resume interface is a must for class driver, it just like a workaround for broken hardware. -- Best Regards, Peter Chen -- 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
