Re: [PATCH] PM / Domains: Allow runtime PM callbacks to be re-used during system PM

[Kevin Hilman <khilman@kernel.org>]

Ulf Hansson <ulf.hansson@linaro.org> writes:

> Runtime PM centric subsystems/drivers may re-use their runtime PM
> callbacks for system PM. Typically that's done via using the runtime PM
> helpers, pm_runtime_force_suspend|resume().
>
> To genpd, this means its runtime PM callbacks may be invoked even when
> runtime PM has been disabled for the device. By checking this condition,
> it allows genpd to skip latency validation and measurement in the system
> PM path. That's needed to enable drivers/subsystems to re-use the runtime
> PM callbacks for system PM.
>
> Fixes: ba2bbfbf6307 ("PM / Domains: Remove intermediate states from the
> power off sequence")
> Reported-by: Cao Minh Hiep <cm-hiep@jinso.co.jp>
> Reported-by: Harunaga <nx-truong@jinso.co.jp>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>
> This patch has only been quick tested on ux500, so further tests are
> welcome and needed. It was reported [1] to point out a certain commit
> causing the regression, but further analyze actually tells that the
> problem been there longer.
>
> So, I decided to point the fixes tag to a commit from where it actually
> becomes quite simple to address the problem. Earlier than that, is just
> not worth the effort.
>
> [1]
> https://lkml.org/lkml/2015/11/16/748
>
> ---
>  drivers/base/power/domain.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index e03b1ad..8f0c2a3 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -390,6 +390,7 @@ static int pm_genpd_runtime_suspend(struct device *dev)
>  	struct generic_pm_domain *genpd;
>  	bool (*stop_ok)(struct device *__dev);
>  	struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
> +	bool system_pm = !pm_runtime_enabled(dev);

nit: I think this 'system_pm' variable name is confusing, especaly
because it just means runtime PM *not* enabled.

Is !pm_runtime_enabled() really sufficient to determine if these are
being called in the context of system PM?

Kevin