linux-kernel - Re: [PATCH v1 2/4] PM / devfreq: Add devm_devfreq_add

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Message-ID: <329a691d-010f-ca2a-22ef-929fb4495ce7@gmail.com>
Date:   Thu, 16 Sep 2021 03:37:29 +0900
From:   Chanwoo Choi <cwchoi00@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>
Cc:     linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v1 2/4] PM / devfreq: Add devm_devfreq_add_governor()

Hi,

There is ordering dependency between devfreq device and devfreq
governor. Theoretically, devfreq governor must be released after
released of devfreq device.

devm_* support the release ordering by the sequence of registration
in probe()?

On 21. 9. 13. 오전 3:44, Dmitry Osipenko wrote:
> Add resource-managed variant of devfreq_add_governor().
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>   drivers/devfreq/devfreq.c  | 26 ++++++++++++++++++++++++++
>   drivers/devfreq/governor.h |  3 +++
>   2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 85faa7a5c7d1..d3af000ec290 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1301,6 +1301,32 @@ int devfreq_add_governor(struct devfreq_governor *governor)
>   }
>   EXPORT_SYMBOL(devfreq_add_governor);
>   
> +static void devm_devfreq_remove_governor(void *governor)
> +{
> +	devfreq_remove_governor(governor);
> +}
> +
> +/**
> + * devm_devfreq_add_governor() - Add devfreq governor
> + * @dev:	device which adds devfreq governor
> + * @governor:	the devfreq governor to be added
> + *
> + * This is a resource-managed variant of devfreq_add_governor().
> + */
> +int devm_devfreq_add_governor(struct device *dev,
> +			      struct devfreq_governor *governor)
> +{
> +	int err;
> +
> +	err = devfreq_add_governor(governor);
> +	if (err)
> +		return err;
> +
> +	return devm_add_action_or_reset(dev, devm_devfreq_remove_governor,
> +					governor);
> +}
> +EXPORT_SYMBOL(devm_devfreq_add_governor);
> +
>   /**
>    * devfreq_remove_governor() - Remove devfreq feature from a device.
>    * @governor:	the devfreq governor to be removed
> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
> index 2d69a0ce6291..0d70a9ad951e 100644
> --- a/drivers/devfreq/governor.h
> +++ b/drivers/devfreq/governor.h
> @@ -94,4 +94,7 @@ static inline int devfreq_update_stats(struct devfreq *df)
>   
>   	return df->profile->get_dev_status(df->dev.parent, &df->last_status);
>   }
> +
> +int devm_devfreq_add_governor(struct device *dev,
> +			      struct devfreq_governor *governor);
>   #endif /* _GOVERNOR_H */
> 


-- 
Best Regards,
Samsung Electronics
Chanwoo Choi