On Fri, 23 Sept 2022 at 14:47, Liu Ying <victor.liu@xxxxxxx> wrote: > > After a device transitions to sleep state through it's system suspend > callback pm_runtime_force_suspend(), the device's driver may still try > to do runtime PM for the device(runtime suspend first and then runtime > resume) although runtime PM is disabled by that callback. The runtime > PM operations would not touch the device effectively and the device is > assumed to be resumed through it's system resume callback > pm_runtime_force_resume(). This sounds like a fragile use case to me. In principle you want to allow the device to be runtime resumed/suspended, after the device has already been put into a low power state through the regular system suspend callback. Normally it seems better to prevent this from happening, completely. That said, in this case, I wonder if a better option would be to point ->suspend_late() to pm_runtime_force_suspend() and ->resume_early() to pm_runtime_force_resume(), rather than using the regular ->suspend|resume() callbacks. This should avoid the problem, I think, no? Note that, the PM core also disables runtime PM for the device in __device_suspend_late(). For good reasons. [...] Kind regards Uffe
