On Wed, 13 Apr 2011, Andiry Xu wrote: > Thanks for the elaborate explanation, that's really helpful. Part of the discussion was wrong; I mixed up xhci_bus_suspend and xhci_pci_suspend. But it looks like you realized what I meant. > I've not got a serial console but I managed to catch some call trace > using a very simple but effective method: use outb(data, 0x80) and check > the LED display on the motherboard. > > xhci_bus_suspend() will check all the ports and suspend them if they are > in U0 state. this makes things different for suspend and hibernation. > > During system suspend, the call trace is like this: > usb_port_suspend(): > Set REMOTE_WAKEUP request to the device; > Suspend the port; > xhci_bus_suspend(): > //The port is already suspended > xhci_pci_suspend() > Suspend the host; > > During system hibernation, the call trace is like this: > xhci_bus_suspend(): > Suspend the port, since it's in U0 state; There should be a call to xhci_bus_resume() at this point, during the second or "thaw" stage. It should put the port back into U0. > usb_port_suspend(): > No REMOTE_WAKEUP request is sent to the device, maybe because it's > suspended? The remote-wakeup request should have been sent because the port should not have been suspended. > Suspend the port; > xhci_pci_suspend(): > Suspend the host; > > So remote wakeup is not working. > > I made a small test, skip the port suspend part in xhci_bus_suspend(): > xhci_bus_suspend(): > //Skip the port suspend part; See if you can trace the call to xhci_bus_resume() that's supposed to appear here. > usb_port_suspend(): > REMOTE_WAKEUP request is sent to the device; > Suspend the port; > xhci_pci_suspend(): > Suspend the host; > > And by doing this, press the USB keyboard on xHCI can wakeup the system > from hibernation. > > The xhci bus suspend/resume is mainly copied from EHCI bus > suspend/resume method, in which EHCI suspend all the ports during bus > suspend. Seems it should be modified for xHCI. Any suggestions? The same scheme should work for both EHCI and xHCI. I can't tell what the problem is. 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
