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Subject: Re: [PATCH v6 2/3] PM / devfreq: Cache OPP table reference in
 devfreq
To:     Hsin-Yi Wang <hsinyi@chromium.org>,
        Viresh Kumar <vireshk@kernel.org>, linux-pm@vger.kernel.org
Cc:     Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@kernel.org>,
        "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        linux-kernel@vger.kernel.org,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Saravana Kannan <saravanak@google.com>
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <876e4164-1d28-9d0e-3b10-28d62099b904@samsung.com>
Date:   Thu, 4 Feb 2021 17:46:58 +0900
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        <CGME20210204081436epcas1p2acb2b052090c18979c48f2c343f6b7aa@epcas1p2.samsung.com>
        <20210204081424.2219311-3-hsinyi@chromium.org>
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Hi Hsin-Yi,

On 2/4/21 5:14 PM, Hsin-Yi Wang wrote:
> From: Saravana Kannan <saravanak@google.com>
> 
> The OPP table can be used often in devfreq. Trying to get it each time can
> be expensive, so cache it in the devfreq struct.
> 
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
>  drivers/devfreq/devfreq.c | 6 ++++++
>  include/linux/devfreq.h   | 2 ++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 6aa10de792b33..a5899c9ae16fc 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -757,6 +757,8 @@ static void devfreq_dev_release(struct device *dev)
>  	if (devfreq->profile->exit)
>  		devfreq->profile->exit(devfreq->dev.parent);
>  
> +	if (devfreq->opp_table)
> +		dev_pm_opp_put_opp_table(devfreq->opp_table);
>  	mutex_destroy(&devfreq->lock);
>  	kfree(devfreq);
>  }
> @@ -844,6 +846,10 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  	}
>  
>  	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
> +	devfreq->opp_table = dev_pm_opp_get_opp_table(dev);
> +	if (IS_ERR(devfreq->opp_table))
> +		devfreq->opp_table = NULL;
> +
>  	atomic_set(&devfreq->suspend_count, 0);
>  
>  	dev_set_name(&devfreq->dev, "%s", dev_name(dev));
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index b6d3bae1c74d8..26ea0850be9bb 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -137,6 +137,7 @@ struct devfreq_stats {
>   *		using devfreq.
>   * @profile:	device-specific devfreq profile
>   * @governor:	method how to choose frequency based on the usage.
> + * @opp_table:	Reference to OPP table of dev.parent, if one exists.
>   * @nb:		notifier block used to notify devfreq object that it should
>   *		reevaluate operable frequencies. Devfreq users may use
>   *		devfreq.nb to the corresponding register notifier call chain.
> @@ -173,6 +174,7 @@ struct devfreq {
>  	struct device dev;
>  	struct devfreq_dev_profile *profile;
>  	const struct devfreq_governor *governor;
> +	struct opp_table *opp_table;
>  	struct notifier_block nb;
>  	struct delayed_work work;
>  
> 

Acked-by: Chanwoo Choi <cw00.choi@samsung.com>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics