linux-kernel - Re: [PATCH] bus: simple-pm-bus: fix forced runtime PM use

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Message-ID: <CAPDyKFr98DraLvOC83rRFa=uKj_hmwS7Lj0L3JqrbqcFuhdWGA@mail.gmail.com>
Date: Fri, 14 Feb 2025 13:36:48 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Johan Hovold <johan+linaro@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Liu Ying <victor.liu@....com>
Subject: Re: [PATCH] bus: simple-pm-bus: fix forced runtime PM use

On Fri, 14 Feb 2025 at 11:21, Johan Hovold <johan+linaro@...nel.org> wrote:
>
> The simple-pm-bus driver only enables runtime PM for some buses
> ('simple-pm-bus') yet has started calling pm_runtime_force_suspend() and
> pm_runtime_force_resume() during system suspend unconditionally.
>
> This currently works, but that is not obvious and depends on
> implementation details which may change at some point.
>
> Add dedicated system sleep ops and only call pm_runtime_force_suspend()
> and pm_runtime_force_resume() for buses that use runtime PM to avoid any
> future surprises.
>
> Fixes: c45839309c3d ("drivers: bus: simple-pm-bus: Use clocks")

This doesn't look like it is needed to me. It isn't broken, right?

> Cc: Liu Ying <victor.liu@....com>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>

Seems reasonable to me, but I think we need an ack from Geert here too.

Anyway, feel free to add:
Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Kind regards
Uffe

> ---
>  drivers/bus/simple-pm-bus.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
> index 5dea31769f9a..d8e029e7e53f 100644
> --- a/drivers/bus/simple-pm-bus.c
> +++ b/drivers/bus/simple-pm-bus.c
> @@ -109,9 +109,29 @@ static int simple_pm_bus_runtime_resume(struct device *dev)
>         return 0;
>  }
>
> +static int simple_pm_bus_suspend(struct device *dev)
> +{
> +       struct simple_pm_bus *bus = dev_get_drvdata(dev);
> +
> +       if (!bus)
> +               return 0;
> +
> +       return pm_runtime_force_suspend(dev);
> +}
> +
> +static int simple_pm_bus_resume(struct device *dev)
> +{
> +       struct simple_pm_bus *bus = dev_get_drvdata(dev);
> +
> +       if (!bus)
> +               return 0;
> +
> +       return pm_runtime_force_resume(dev);
> +}
> +
>  static const struct dev_pm_ops simple_pm_bus_pm_ops = {
>         RUNTIME_PM_OPS(simple_pm_bus_runtime_suspend, simple_pm_bus_runtime_resume, NULL)
> -       NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
> +       NOIRQ_SYSTEM_SLEEP_PM_OPS(simple_pm_bus_suspend, simple_pm_bus_resume)
>  };
>
>  #define ONLY_BUS       ((void *) 1) /* Match if the device is only a bus. */
> --
> 2.45.3
>