Am Freitag, 2. März 2007 17:27 schrieb Alan Stern:
> On Thu, 1 Mar 2007, Oliver Neukum wrote:
>
> > Down an interface and it stays down. Suspend an interface and it ...
>
> ... and it stays suspended until the kernel tries to send a packet out
> through that interface or until a packet is received (assuming proper
> hardware wakeup support is available and enabled). That's pretty much
> exactly how I'd want my interface to behave if I was trying to save power.
That is how I expect autoconfig to work. If I suspend a device manually I
expect to to stay suspended until it say otherwise.
> > > Take a look at the definition of pm_message_t and tell me where you think
> > > the information could be stored.
> >
> > How many in kernel data structures have been changed?
>
> How many times have you succeeded in getting Pavel to change any of his
> data structures? :-)
I'll try voodoo. Or maybe I promise him a quadruped.
> > Though if we limit
> > pm to autosuspend the point is moot.
>
> This boils down to one of our unanswered questions: How can we allow the
> user to suspend a device if the driver wants remote-wakeup capability but
Export the conditionality in sysfs? "NeedsRemoteWakeup" ?
> remote wakeup is disabled? Autosuspend won't do it, for a simple reason:
> Autosuspend is always supposed to be safe, and without remote wakeup
> it might not be safe. We will need something stronger.
>
> The other unanswered question is whether we need a separate attribute
> (with separate permissions) for enabling/disabling autosuspend. Note
> that this attribute would be per-device and not per-interface, even if we
> do have a per-interface delay attribute.
Yes, we need that.
> It would be nice if we could solve both questions together. For example,
> we might have a device attribute that would allow the superuser to:
>
> Turn off autosuspend completely;
>
> Allow autosuspend to operate normally, using the delay value
> specified in the other attribute file;
>
> Force an immediate suspend, even if remote wakeup is disabled.
Have a delay attribute per interface and give each device an attribute
"SuspensionState" with the permissible values "on", "auto" & "suspend"
Handle RemoteWakeup as an orthogonal issue.
Regards
Oliver
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