Hello, Reviving this old thread. On Monday 07 Mar 2016 11:10:08 Ulf Hansson wrote: > [...] > > >> I agree, that's a better idea. Drivers shouldn't call > >> pm_runtime_force_resume() if they haven't called > >> pm_runtime_force_suspend(), so checking the PM use count should be fine. > >> I'll modify the patch, test it and resubmit. > > > > I gave it an unfortunately unsuccessful try. The problem I ran into is > > that device_prepare() calls pm_runtime_get_noresume() calls > > pm_runtime_get_noresume(), with the corresponding pm_runtime_put() call > > being performed in device_complete(). The device power usage_count is > > thus always non-zero in the system resume handler, so I can't base the > > decision on that. > > As Alan said, let's just check against 1 instead. I gave this a try, and unfortunately it won't work. pm_genpd_prepare() resumes devices without increasing the usage count, which leads to the device always being active in pm_runtime_force_suspend(). The usage count will be 1 if the device was suspended prior to entering system suspend (due to the pm_runtime_get_noresume() call in device_prepare()) or higher than 1 if the device was active. However, pm_genpd_prepare() will not resume the device if suspend_power_off is set. In that case the device will be suspended with a usage count of 1 in pm_runtime_force_suspend() or active with a usage count higher than 1. We thus can't detect at resume time whether we have force-suspended the device using the usage count. Unless someone has another clever idea I'll keep the power.is_force_suspended flag and protect it with power.lock. > > I also noticed that pm_genpd_prepare() runtime-resumes the device (when > > the power domain is in the GPD_STATE_ACTIVE state). I don't know why that > > is, but it means that in practice my device gets runtime-resumed when > > suspending the system while it could stay runtime-suspended in practice. > > I am aware of this and it's on my TODO list of improvements of genpd, > The issue is related to an unoptimized behaviour for how genpd deal > with wakeups during system PM. Looking forward to seeing patches :-) -- Regards, Laurent Pinchart
