On Friday, September 25, 2015 10:29:55 AM Alan Stern wrote: > On Fri, 25 Sep 2015, Rafael J. Wysocki wrote: > > > We are missing the "no remote wakeup" bit now (well, there is a PM QoS flag, > > but it isn't very useful, so I'd prefer to replace it with a "no remote > > wakeup" > > bit in struct dev_pm_info or something similar). > > > > That is actually quite important, because (a) we can save energy but not > > configuring the device to do remote wakeup in the first place and (b) that > > may involve more than just the driver (for example, disabling PCI or ACPI > > remote wakeup involves the bus type or similar). > > > > So it looks like we need to be able to distinguish between "runtime suspend > > with remote wakeup" and "runtime suspend without remote wakeup". > > > > And if we do the latter, we may not even need the "inhibit" thing any more, > > because suspended devices without that are not configured to do remote > > wakeup > > cannot really signal anything in the majority of cases. > > That works only for drivers that use autosuspend to go to low power in > between events. It doesn't work for drivers that remain at full power > as long as the device file is open. That kind of driver does require > an "inhibit" interface.
Or an interface allowing user space to trigger pm_request_idle() for them. So user space would change the "no remote wakeup" setting and then do the "try to suspend now" thing. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
