linux-kernel - Re: [PATCH v3 1/3] PM: runtime: add devm_pm_runtime

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Date:   Thu, 5 Aug 2021 00:02:54 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Taniya Das <tdas@...eaurora.org>,
        Michael Turquette <mturquette@...libre.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v3 1/3] PM: runtime: add devm_pm_runtime_enable helper

On Wed, 4 Aug 2021 at 21:07, Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Sat, Jul 31, 2021 at 9:50 PM Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
> >
> > A typical code pattern for pm_runtime_enable() call is to call it in the
> > _probe function and to call pm_runtime_disable() both from _probe error
> > path and from _remove function. For some drivers the whole remove
> > function would consist of the call to pm_remove_disable().
> >
> > Add helper function to replace this bolierplate piece of code. Calling
> > devm_pm_runtime_enable() removes the need for calling
> > pm_runtime_disable() both in the probe()'s error path and in the
> > remove() function.
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> >  drivers/base/power/runtime.c | 17 +++++++++++++++++
> >  include/linux/pm_runtime.h   |  4 ++++
> >  2 files changed, 21 insertions(+)
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 8a66eaf731e4..ec94049442b9 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -1447,6 +1447,23 @@ void pm_runtime_enable(struct device *dev)
> >  }
> >  EXPORT_SYMBOL_GPL(pm_runtime_enable);
> >
> > +static void pm_runtime_disable_action(void *data)
> > +{
> > +       pm_runtime_disable(data);
> > +}
> > +
> > +/**
> > + * devm_pm_runtime_enable - devres-enabled version of pm_runtime_enable.
> > + * @dev: Device to handle.
> > + */
> > +int devm_pm_runtime_enable(struct device *dev)
> > +{
> > +       pm_runtime_enable(dev);
> > +
> > +       return devm_add_action_or_reset(dev, pm_runtime_disable_action, dev);
>
> When exactly is pm_runtime_disable_action() going to run by this rule?
>  When the device goes away or when the driver is unbound from it?

When the driver is unbound (either because probe() returns an error or
because __device_release_driver() is being called).
This corresponds to a typical call to pm_runtime_disable() from the
probe()'s error path or in the remove() callback.

> > +}
> > +EXPORT_SYMBOL_GPL(devm_pm_runtime_enable);
> > +
> >  /**
> >   * pm_runtime_forbid - Block runtime PM of a device.
> >   * @dev: Device to handle.
> > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
> > index aab8b35e9f8a..222da43b7096 100644
> > --- a/include/linux/pm_runtime.h
> > +++ b/include/linux/pm_runtime.h
> > @@ -59,6 +59,8 @@ extern void pm_runtime_put_suppliers(struct device *dev);
> >  extern void pm_runtime_new_link(struct device *dev);
> >  extern void pm_runtime_drop_link(struct device_link *link);
> >
> > +extern int devm_pm_runtime_enable(struct device *dev);
> > +
> >  /**
> >   * pm_runtime_get_if_in_use - Conditionally bump up runtime PM usage counter.
> >   * @dev: Target device.
> > @@ -253,6 +255,8 @@ static inline void __pm_runtime_disable(struct device *dev, bool c) {}
> >  static inline void pm_runtime_allow(struct device *dev) {}
> >  static inline void pm_runtime_forbid(struct device *dev) {}
> >
> > +static inline int devm_pm_runtime_enable(struct device *dev) { return 0; }
> > +
> >  static inline void pm_suspend_ignore_children(struct device *dev, bool enable) {}
> >  static inline void pm_runtime_get_noresume(struct device *dev) {}
> >  static inline void pm_runtime_put_noidle(struct device *dev) {}
> > --
> > 2.30.2
> >



-- 
With best wishes
Dmitry