On Fri, 9 Nov 2012, Huang Ying wrote: > On Thu, 2012-11-08 at 12:07 -0500, Alan Stern wrote: > > On Thu, 8 Nov 2012, Rafael J. Wysocki wrote: > > > > > > > > is it a good idea to allow to set device state to SUSPENDED if the > > > > > > device > > > > > > is disabled? > > > > > > > > > > No, it is not. The status should always be ACTIVE as long as > > > > > usage_count > 0. > > > > That isn't strictly true, because pm_runtime_get_noresume violates this > > rule. What the PM core actually does is prevent a transition from the > > ACTIVE state to the SUSPENDING/SUSPENDED state if usage_count > 0, > > _provided_ runtime PM is enabled. There's no such restriction when it > > is disabled. > > Usage count may be not a issue for the end user. But "on" in "control" > sysfs file + SUSPENDED can be confusing for the end user. Maybe we need > to check dev->power.runtime_auto in pm_runtime_set_suspended().
You are confusing the issue by raising two separate (though related) questions. The first question: How should the PCI subsystem prevent the parents of driverless VGA devices from being runtime suspended while userspace is accessing them? The second question: Should the PM core allow devices that are disabled for runtime PM to be in the SUSPENDED state when dev->power.runtime_auto is clear? Assuming we don't want to allow this, there's a third question: Should pm_runtime_allow call pm_runtime_set_suspended if the device is disabled? Alan Stern -- 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/
