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SubjectRe: [PATCH] usb: chipidea: host: Disable port power only if previously enabled
On Thu, Dec 26, 2019 at 02:46:15PM -0500, 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.
That is what I would have assumed, but test code shows that it doesn't

> 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

usb_hub_set_port_power() operates on a port of the hub. hub_activate()
operates on the hub itself, or at least I think it does. I don't know
how to convert the calls. Also, there are more calls to hub_power_on()
in the same function. Can you provide more details on what to do,
or even better a patch for me to test ?


> 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).
> Alan Stern

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