Hi Kevin, On Fri, Mar 13, 2015 at 7:01 PM, Kevin Hilman <khil...@kernel.org> wrote: > Geert Uytterhoeven <ge...@linux-m68k.org> writes: >> On Wed, Mar 11, 2015 at 11:08 PM, Rafael J. Wysocki <r...@rjwysocki.net> >> wrote: >>> More CCes. >>> >>> On Wednesday, March 11, 2015 08:27:28 AM Eric Anholt wrote: >>>> If we've declared a power domain in the OF, and the OF node is found >>>> but the requested domain hasn't been registered on it yet, then we >>>> probably have just tried to probe before the power domain driver has. >>>> Defer our device's probe until it shows up. >>>> >>>> Signed-off-by: Eric Anholt <e...@anholt.net> >>> >>> Kevin, Ulf, any chance to have a look at this, please? >>> >>>> --- >>>> >>>> I ran into this when turning my ad-hoc code for BCM2835 (Raspberry Pi) >>>> USB poweron support in the DWC2 controller to an OF-based power domain >>>> declaration. >> >> I guess you are initializing the PM domains from module_init()? >> >> I use core_initcall() in arch/arm/mach-shmobile/pm-rmobile.c to make sure >> it's >> initialized earlier, as e.g. the interrupt controller uses >> postcore_initcall(). > > Yeah, I think most existing users are initizling PM domains early, but IMO > we should be working towards supporting PM domains that are created > later as well (as this patch does.)
Sure. When interrupt controllers are involved (yes, they can be in a PM (Clock) Domain too), there are definitely some complex issues to resolve in the core OF probing code first. Cfr. the bug mentioned in http://marc.info/?l=devicetree&m=142325419327559&w=2 >>>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c >>>> index ba4abbe..2b93c98 100644 >>>> --- a/drivers/base/power/domain.c >>>> +++ b/drivers/base/power/domain.c >>>> @@ -2064,7 +2064,7 @@ EXPORT_SYMBOL_GPL(of_genpd_del_provider); >>>> struct generic_pm_domain *of_genpd_get_from_provider( >>>> struct of_phandle_args *genpdspec) >>>> { >>>> - struct generic_pm_domain *genpd = ERR_PTR(-ENOENT); >>>> + struct generic_pm_domain *genpd = ERR_PTR(-EPROBE_DEFER); >> >> Currently platform_drv_probe() just continues if dev_pm_domain_attach() >> returns >> a different error than -EPROBE_DEFER, which is what you are seeing. >> >> Your change does have the side effect that a new DT with PM domains won't >> work on an older kernel that doesn't have the PM domain driver yet. > > Is that a real problem though? Using newer DTs on older kernels can > cause many types of problems. It means we cannot describe everything in (stable) DT before all support code has been implemented. Ignoring that, it enforces strict merge order. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/