On 04/05/2021 12:08:58+0200, Martin Kaiser wrote: > Thus wrote Alexandre Belloni (alexandre.belloni@xxxxxxxxxxx): > > > > platform_set_drvdata(pdev, imxdi); > > > > + device_set_wakeup_capable(&pdev->dev, true); > > > Maybe it makes sense to simply use device_init_wakeup here. > > the explanation for device_init_wakeup > > "By default, most devices should leave wakeup disabled. The exceptions > are devices that everyone expects to be wakeup sources: keyboards, power > buttons, ..." > > made me think that device_set_wakeup_capable is more appropriate here. I > can change this if you want. > Doesn't everyone expect the RTC to be a wakeup source? :) > However, if I compile rtc-imxdi as a module and use device_init_wakeup, > the module can't be unloaded any more. The reason is that alarmtimer > (kernel/time/alarmtimer.c) starts using rtc-imxdi as its backing rtc > device and holds a reference to it. It seems that alarmtimer has no way > to relinquish its backing rtc device, regardless of any pending alarms. > > What is the right approach here? Are there any rtc drivers that act as a > wakeup source and can still be unloaded if compiled as a module? > Yes, when you don't have alarmtimer ;) I honestly think the RTC selection needs to be a bit more dynamic but at the same time, it would not be great to change it at suspend time. I guess the best way would be to allow module unloading and tracking when the RTC disappears. -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
