On Tue, 2014-09-09 at 13:25 -0400, Alan Stern wrote:
> On Tue, 9 Sep 2014, Alan Stern wrote:
>
> > On Tue, 9 Sep 2014, Oliver Neukum wrote:
> >
> > > On Tue, 2014-09-09 at 11:23 -0400, Alan Stern wrote:
> > > > On Tue, 9 Sep 2014, Oliver Neukum wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > Johan's patch means that for the affected touchscreen the port
> > > > > can never be powered off. It seems to me that this needs a special
> > > > > flag. What do you think?
> > > >
> > > > Why can't the port be powered off?
> > >
> > > needs_remote_wakeup is permanently set.
> >
> > That's okay, then. We never power-down a port if the attached device
> > is enabled for remote wakeup. See the last few lines in
> > usb_port_suspend() in hub.c.
>
> Sorry, I misunderstood. You meant that the port can't be powered off
> because remote wakeup is enabled, but the driver doesn't really need
> remote wakeup even though it sets the needs_remote_wakeup flag.
>
> In other words, you want to power-off the port, but are prevented from
> doing so by the fact that the device disconnects itself from the bus if
> it is suspended without remote wakeup.
>
> My feeling is that this is not worth the effort. Leave the port
> powered on. Or let the device disconnect itself and then power-off the
> port.
It would reconnect. For a mouse I wouldn't bother, but here we are
dealing with a laptop's touchscreen. We'd break D3cold for the HC
permanently and totally.
Regards
Oliver
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