On Tue, 13 May 2014, Rafael J. Wysocki wrote: > > Maybe the call to __pm_runtime_disable() should be moved from > > __device_suspend_late() to __device_suspend(), after the callback has > > been invoked (or skipped, as the case may be). Then after runtime PM > > has been disabled, you can check the device's status has changed and go > > back to invoke the callback if necessary. > > We moved __pm_runtime_disable() to __device_suspend_late() to be able to > use pm_runtime_resume() in __device_suspend() (and we actually do that in > some places now). > > But, in principle, we can do __pm_runtime_disable() temporarily in some place > between ->prepare() and ->suspend(), it doesn't matter if that's in > device_prepare() in __device_suspend() really. It should be as late as possible, to allow for detecting wakeup requests. > Then, we can check the device's > runtime PM status (that'd need to be done carefully to take the disabling into > account) and > (1) if the device is runtime-suspended, set direct_complete for it without > enabling runtime PM, or > (2) if the device is not runtime-suspended, clear direct_complete for it > and re-enable runtime PM. > and in case of (1) we would re-enable runtime PM in device_complete(). > > That should work I suppose? Yes; it's similar to what I proposed. Note that this can be skipped if direct_complete is already clear. > Of course, question is what ->prepare() is supposed to do then if it needs > to check the state of the device before deciding whether or not to return 1. > I guess it would need to disable runtime PM around that check too. It would be surprising if ->prepare() needed to make any difficult checks. This would imply that the device could have multiple runtime-suspend states, some of which are appropriate for system suspend while others aren't. Not impossible, but I wouldn't expect it to come up often. Besides, as I mentioned before, we never have to worry about status changes. If one occurs while ->prepare() is running or afterward, it means the device is runtime-resumed and therefore the setting of direct_complete doesn't matter. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
