On Thu, 19 Oct 2023 at 19:08, Stephan Gerhold <stephan@xxxxxxxxxxx> wrote: > > On Thu, Oct 19, 2023 at 05:19:53PM +0200, Ulf Hansson wrote: > > On Thu, 19 Oct 2023 at 16:49, Stephan Gerhold <stephan@xxxxxxxxxxx> wrote: > > > On Thu, Oct 19, 2023 at 04:12:56PM +0200, Ulf Hansson wrote: > > > > On Thu, 19 Oct 2023 at 15:05, Stephan Gerhold <stephan@xxxxxxxxxxx> wrote: > > > > > On Thu, Oct 19, 2023 at 01:26:19PM +0200, Ulf Hansson wrote: > > > > > > BTW, if you really need something like the above, the proper way to do > > > > > > it would instead be to call device_set_awake_path() for the device. > > > > > > > > > > > > This informs genpd that the device needs to stay powered-on during > > > > > > system suspend (assuming that GENPD_FLAG_ACTIVE_WAKEUP has been set > > > > > > for it), hence it will keep the corresponding PM domain powered-on > > > > > > too. > > > > > > > > > > Thanks, I can try if this works as alternative to the > > > > > dev_pm_syscore_device()! > > > > > > > > Yes, please. We don't want to abuse the dev_pm_syscore_device() thingy. > > > > > > Could you clarify the idea behind GENPD_FLAG_ACTIVE_WAKEUP? Would I set > > > it conditionally for all RPMPDs or just the ones consumed by the CPU? > > > How does the genpd *provider* know if one of its *consumer* devices > > > needs to have its power domain kept on for wakeup? > > > > We are thinking of the GENPD_FLAG_ACTIVE_WAKEUP as a platform > > configuration type of flag for the genpd in question. The consumer > > driver shouldn't need to know about the details of what is happening > > on the PM domain level - only whether it needs its device to remain > > powered-on during system suspend or not. > > > > Thanks! I will test if this works for RPMPD and post new versions of the > patches. By coincidence I think this flag might actually be useful as > temporary solution for CPR. If I: > > 1. Change $subject patch to use device_set_awake_path() instead, and > 2. Set GENPD_FLAG_ACTIVE_WAKEUP for the RPMPD genpds, but > 3. Do *not* set GENPD_FLAG_ACTIVE_WAKEUP for the CPR genpd. > > Then the genpd ->power_on|off() callbacks should still be called > for CPR during system suspend, right? :D Yes, correct, that should work fine! > > > I suspect that the GENPD_FLAG_ACTIVE_WAKEUP is probably okay to set > > for most genpds, but there may be some exceptions. > > > > Out of curiosity, do you have an example for such an exception where > GENPD_FLAG_ACTIVE_WAKEUP shouldn't be set, aside from workarounds like > I just described? > > As you said, the consumer device should just say that it wants to stay > powered for wakeup during suspend. But if its power domains get powered > off, I would expect that to break. How could a genpd driver still > provide power without being powered on? Wouldn't that rather be a low > performance state? I think this boils down to how the power-rail that the genpd manages, is handled by the platform during system suspend. In principle there could be some other separate logic that helps a FW/PMIC to understand whether it needs to keep the power-rail on or not - no matter whether the genpd releases its vote for it during system suspend. This becomes mostly hypothetical, but clearly there are a lot of genpd/platforms that don't use GENPD_FLAG_ACTIVE_WAKEUP too. If those are just mistakes or just not needed, I don't actually know. Kind regards Uffe
