linux-kernel - Re: [PATCH v2 1/5] PM: runtime: add devm_pm_runtime

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Date:   Wed, 28 Jul 2021 13:04:25 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.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>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 1/5] PM: runtime: add devm_pm_runtime_enable helper

On Wed 28 Jul 07:24 PDT 2021, Dmitry Baryshkov wrote:

> Add helper function handling typical driver action: call
> pm_runtime_enable at the probe() time and disable it during remove().
> 

This says what the patch does, but it doesn't say why we would like
these helpers - i.e. the fact that it's quite common across the kernel
to have error handlers and remove functions that simply has to do
pm_runtime_disable().

> 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.

() on the function name.

> + * @dev: Device to handle.

Returns: 0 on success, negative errno on failure

Regards,
Bjorn

> + */
> +int devm_pm_runtime_enable(struct device *dev)
> +{
> +	pm_runtime_enable(dev);
> +
> +	return devm_add_action_or_reset(dev, pm_runtime_disable_action, dev);
> +}
> +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
>