On 2 October 2014 11:42, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > On 1 October 2014 21:50, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: >> On Wednesday, October 01, 2014 06:18:58 PM Sylwester Nawrocki wrote: >>> On 01/10/14 16:41, Ulf Hansson wrote: >>> > At ->probe() it's common practice for drivers/subsystems to bring their >>> > devices to full power and without depending on CONFIG_PM_RUNTIME. >>> > >>> > We could also expect that drivers/subsystems requires their device's >>> > corresponding PM domains to be powered, to successfully complete a >>> > ->probe() sequence. >>> > >>> > Align to the behavior above, by ensuring all PM domains are powered >>> > prior initialization of a generic PM domain. >>> > >>> > Do note, since the generic PM domain will try to power off unused PM >>> > domains at late_init, there should be no increased power consumption >>> > over time, but potentially during boot. >>> >>> Wouldn't it be a better idea to power on the power domains which are >>> turned off only when CONFIG_PM_RUNTIME is not enabled ? I had a plan >>> to submit a patch doing that but unfortunately this has fallen through >>> the cracks. At the moment mach-exynos/pm_domains.c is not even built in >>> when CONFIG_PM_RUNTIME is disabled. > > Yes, that's the approach I also intend to take in the next step. > > But, it's not that simple. Since this requires a mechanism for drivers > to bring their device's PM domains into power state prior doing probe. > We don't have such today. I do have some ideas about this, but I think > we need to keep that as a separate discussion. > >>> >>> I don't like the behaviour introduced in this patch to be the default, >>> i.e. turning all possible power domains during boot sequence, even if >>> some are not used and not needed. While we're trying to decrease the >>> power consumption in any possible way this doesn't help at all. > > This will hit only during boot, until late_init. Unless you have a > platform that keeps rebooting all the time, is this really a big > worry? > > Still, I certainly agree that we should strive for a solution where > it's possible to leave PM domains powered off at init. It's should be /s/ It's should/ It shouldn't > too hard to support this from genpd point of view, but > drivers/subsystems will need some adaptations. > >> >> Agreed (as stated before). >> >> And I'm wondering why that comment of mine was ignored? > > Sorry, if missed to comment of that. I guess I have at this point. > > Kind regards > Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
 |