Messages in this thread | | | Date | Tue, 19 Dec 2006 20:32:51 +0000 | From | Matthew Garrett <> | Subject | Re: Changes to sysfs PM layer break userspace |
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On Tue, Dec 19, 2006 at 09:23:05PM +0100, Arjan van de Ven wrote: > On Tue, 2006-12-19 at 20:08 +0000, Matthew Garrett wrote: > > I'm not sure. Suspending the chip means you lose things like link beat > > detection, so it's not something you necessarily want to automatically > > tie to something like interface status. > > right now the "spec" for Linux network drivers assumes that you put the > NIC into D3 on down, except for cases where Wake-on-Lan is enabled etc.
Really? I can't find any drivers that seem to do this. The only calls to pci_set_power_state seem to be in the suspend, resume, init and exit routines.
> > Some chips support more > > fine-grained power management, so we could do something more sensible in > > that case - but right now, there doesn't seem to be a lot of driver > > support for it. > > sounds like that's the right approach at least .. not talking to the PCI > hardware directly from userspace...
I'd certainly agree that that's the right thing to do, but userspace has a habit of using whatever functionality /is/ available to get to a given end. The semantics of the device/power/state file were never made terribly clear, and it did have the desired effect of suspending the device. Removing it without providing warning or a transition pathway is a pain.
> I can see the point of having more than just "UP" and "DOWN" as > interface states; "UP", "DOWN" and "OFF" for example...
Agreed.
-- Matthew Garrett | mjg59@srcf.ucam.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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