On Fri, 27 Dec 2019, Peter Chen wrote: > On 19-12-26 14:46:15, Alan Stern wrote: > > On Thu, 26 Dec 2019, Guenter Roeck wrote: > > > > > On shutdown, ehci_power_off() is called unconditionally to power off > > > each port, even if it was never called to power on the port. > > > For chipidea, this results in a call to ehci_ci_portpower() with a request > > > to power off ports even if the port was never powered on. > > > This results in the following warning from the regulator code. > > > > That's weird -- we should always power-on every port during hub > > initialization. > > > > It looks like there's a bug in hub.c:hub_activate(): The line under > > HUB_INIT which calls hub_power_on() should call > > usb_hub_set_port_power() instead. In fact, the comment near the start > > of hub_power_on() is wrong. It says "Enable power on each port", but > > in fact it only enables power for ports that had been powered-on > > previously (i.e., the port's bit in hub->power_bits was set). > > Apparently this got messed up in commit ad493e5e5805 ("usb: add usb > > port auto power off mechanism"). > > > > Now, the chipidea driver may still need to be updated, because > > ehci_turn_off_all_ports() will still be called during shutdown and it > > will try to power-down all ports, even those which are already powered > > down (for example, because the port is suspended). > > > > Hi Alan, > > When the port is suspended, why it was turned off? If it was turned > off, how could respond wakeup event? You're right; if a port is powered off then it can't respond to wakeup events. But if the power/wakeup attribute is set to "disabled" then the port doesn't need to respond to wakeup events. In that situation, usbcore may decide to power-down the port. Alan Stern