Am Dienstag, 15. Mai 2007 22:03 schrieb Alan Stern:
> On Tue, 15 May 2007, Oliver Neukum wrote:
>
> > Am Dienstag, 15. Mai 2007 20:40 schrieb Alan Stern:
> > > On Tue, 15 May 2007, Oliver Neukum wrote:
> >
> > > > Fourthly, some drivers cannot do it in principal, because they cannot
> > > > restore a device's state, eg. printer, scanner, ...
> > >
> > > Yes. Conversely, some drivers don't care about it at all because they
> > > don't maintain any state in the device.
> >
> > That I doubt. There's always the relationship with open files. Usually
> > eg. with mice you don't care because you use /dev/input/mice, but
> > if for any reason you use a specific mouse, you care.
>
> That relationship isn't stored in the device! Even if you use a
The physical identity of the device determines it.
> specific mouse, you don't care if the mouse gets reset -- the usbhid
> driver won't need to restore any of the mouse's state.
But I do care about my device still being my device. A loss of power
does affect that.
> > I think you are mixing things that shouldn't be. Recovery from a loss
> > of power is different from getting reset for resume. In the latter case
> > identity is not in doubt.
>
> So then do you want to add _two_ new methods: one for reset_resume and
> the other for powerloss_resume? If we do, reset_resume will be used
> only for devices with the USB_QUIRK_RESET_RESUME flag set.
Yes & yes. Specific methods are good.
> > A driver that does not resume() but autosuspend is buggy. Plain and simple.
> >
> > > reset_resume() method. In such cases we could skip the rebinding.
> >
> > Indeed. But if we do that we must unbind. We can't have undead devices.
>
> Not at all -- we should fix the driver! If it claims to support
> autosuspend then it should also be able to handle reset_resume without
> any need for rebinding.
Why? Or rather which kind? Quirky devices are very rare. Why would
all drivers need to handle that? As for powerloss, a printer driver can
never do that, as it cannot restore the printer's setting. Likewise anything
claimed by usbfs. There are other examples.
Regards
Oliver
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