Re: [PATCH v3] platform/x86/hp: Avoid spurious wakeup on HP ProOne 440

[Kai-Heng Feng]

On Fri, Sep 6, 2024 at 10:22 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, Sep 06, 2024 at 01:30:47PM +0800, Kai-Heng Feng wrote:
> > The HP ProOne 440 has a power saving design that when the display is
> > off, it also cuts the USB touchscreen device's power off.
> >
> > This can cause system early wakeup because cutting the power off the
> > touchscreen device creates a disconnect event and prevent the system
> > from suspending:
>
> Is the touchscreen device connected directly to the root hub?  If it is
> then it looks like there's a separate bug here, which needs to be fixed.
>
> > [  445.814574] hub 2-0:1.0: hub_suspend
> > [  445.814652] usb usb2: bus suspend, wakeup 0
>
> Since the wakeup flag is set to 0, the root hub should not generate a
> wakeup request when a port-status-change event happens.

The disconnect event itself should not generate a wake request, but
the interrupt itself still needs to be handled.

>
> > [  445.824629] xhci_hcd 0000:00:14.0: Port change event, 1-11, id 11, portsc: 0x202a0
> > [  445.824639] xhci_hcd 0000:00:14.0: resume root hub
>
> But it did.  This appears to be a bug in one of the xhci-hcd suspend
> routines.

So should the xhci-hcd delay all interrupt handling after system resume?

>
> Alternatively, if the touchscreen device is connected to an intermediate
> hub then that intermediate hub should not be allowed to generate wakeup
> events.  That's determined by userspace, though, not by the kernel.

It's connected to roothub.

Kai-Heng

>
> Alan Stern