Re: [PATCH v2 06/14] USB: centralize usb port power policy

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On Mon, 2013-11-25 at 11:05 -0800, Dan Williams wrote:
> On Mon, Nov 25, 2013 at 3:33 AM, Oliver Neukum <oneukum@xxxxxxx> wrote:
> > On Fri, 2013-11-22 at 12:18 -0800, Dan Williams wrote:
> >> On Fri, Nov 22, 2013 at 2:39 AM, Oliver Neukum <oneukum@xxxxxxx> wrote:
> >> > On Fri, 2013-11-22 at 01:07 -0800, Dan Williams wrote:
> >> >> Move all port power policy evaluation to usb_port_runtime_suspend().
> >> >> Makes it clearer what blocks port power off and is preparation for
> >> >> follow on changes that
> >> >> 1/ make a usb_port a proper (device model) parent
> >> >>    of a usb_device
> >> >> 2/ advertise to userspace what constraints are keeping a
> >> >>    port powered
> >> >> 3/ changing the meaning of the usb_port runtime suspended
> >> >>    state.
> >> >> 4/ add new constraints peer-port-power-state and connect_type
> >> >
> >> > It seems to me that if you use reset_resume() you must
> >> > check whether all children further down in the tree support
> >> > reset_resume() in their drivers.
> >> >
> >>
> >> If a device does not support reset_resume I expect it will fail
> >> autosuspend_check().  When that happens the device will stay in the
> >
> > Why? They would fail only if, needs_remote_wakeup were set.
> > It may or may not be.
> 
> It also fails in the simple case where the driver has disabled
> autosuspend for the device.
> 
> If a device is enabling autosuspend and does not support reset_resume
> it will already have issues with its parent hub going into
> autosuspend.  The hub resume path forces reset_resume for child
> devices.

Can you please elaborate? It seems to me that hub_activate() deals
with a survival of the power session just fine.
There seems to be a fundamental misunderstanding here.

	Regards
		Oliver


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