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From: Geert Uytterhoeven <>
To: "Rafael J. Wysocki" <>
Cc: Eric Anholt <>, Kevin Hilman <>,
	Ulf Hansson <>,
	"" <>,
	Tomasz Figa <>,
	Greg Kroah-Hartman <>,
	Linux PM list <>
Subject: Re: [PATCH] PM / Domains: If an OF node is found but no device probed yet, defer.
Date: Wed, 11 Mar 2015 23:14:05 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <6516096.HanqZ05BXy@vostro.rjw.lan>

On Wed, Mar 11, 2015 at 11:08 PM, Rafael J. Wysocki <> 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 <>
> 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().

>> drivers/base/power/domain.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 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.

Whether this is a good or a bad thing depends on your bootloader. If all PM
domains are powered when Linux boots, it can work without PM domain driver.
Since DT PM domains are quite recent, I guess this is the case for most
existing SoCs.

>>       struct of_genpd_provider *provider;
>>       mutex_lock(&of_genpd_mutex);



Geert Uytterhoeven -- There's lots of Linux beyond ia32 --

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

  reply	other threads:[~2015-03-11 22:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-11 15:27 [PATCH] PM / Domains: If an OF node is found but no device probed yet, defer Eric Anholt
2015-03-11 22:08 ` Rafael J. Wysocki
2015-03-11 22:14   ` Geert Uytterhoeven [this message]
2015-03-12 19:31     ` Eric Anholt
2015-03-13 18:01     ` Kevin Hilman
2015-03-16  8:44       ` Geert Uytterhoeven
2015-03-16 10:12       ` Ulf Hansson
2015-03-18 22:55         ` Eric Anholt
2015-03-12  8:39 ` Ulf Hansson

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