linux-kernel - Re: [PATCH] PM / Domains: If an OF node is found but no device probed yet, defer.

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Date:	Thu, 12 Mar 2015 09:39:45 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Eric Anholt <eric@...olt.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Kevin Hilman <khilman@...aro.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] PM / Domains: If an OF node is found but no device probed
 yet, defer.

On 11 March 2015 at 16:27, Eric Anholt <eric@...olt.net> 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.

As Geert also pointed out in his reply; I think the proper solution is
to move the registration of the PM domain to an earlier init level.

The main reason from my side is that I don't want us to invent yet
another "probe scenario", since we currently already have some
difficulties to handle the existing ones. Like the issue below.
http://marc4.marc.info/?t=142392781500004&r=1&w=2

Kind regards
Uffe

>
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
>
> 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.
>
> 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);
>         struct of_genpd_provider *provider;
>
>         mutex_lock(&of_genpd_mutex);
> --
> 2.1.4
>
> --
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