Re: [PATCH] xhci: Disable connect, disconnect and over-current wakeup on system suspend

[Alan Stern]

On Thu, Aug 17, 2023 at 09:13:55PM +0800, Kai-Heng Feng wrote:
> On Thu, Aug 17, 2023 at 8:52 PM Mathias Nyman
> <mathias.nyman@xxxxxxxxxxxxxxx> wrote:
> >
> > On 17.8.2023 14.18, Oliver Neukum wrote:
> > > On 17.08.23 11:33, Kai-Heng Feng wrote:
> > >
> > > Hi,
> > >
> > >> So for system-wide suspend, also disable connect, disconnect and
> > >> over-current wakeup to prevent spurious wakeup.
> > >
> > > isn't this breaking the ability to effectively use your root hub
> > > as a source of system wakeups? That is, even if you want the
> > > system to wake up if somebody attaches a new device, it no longer works?
> > >
> >
> > I got the same concern about this.
> 
> Per my test, it doesn't work with or without this change. This applies
> to disconnection too, disconnecting USB devices doesn't wake the
> system up.
> Furthermore, if the newly attached device is a USB keyboard, pressing
> it doesn't wake the system up either. Probably because remote wakeup
> isn't configured when the system is suspended.

If remote wakeup isn't enabled then the do_wakeup variable will be 0, 
so your patch wouldn't make any difference.  The question is what 
happens when remote wakeup _is_ enabled.

Did you check the settings in the controller's and root hub's 
power/wakeup sysfs files?

Alan Stern