linux-kernel - Re: [PATCH v5 04/12] PM / devfreq: Add struct devfreq

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Message-id: <5B3C3632.1010706@samsung.com>
Date:   Wed, 04 Jul 2018 11:51:30 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Matthias Kaehlcke <mka@...omium.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     Kyungmin Park <kyungmin.park@...sung.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Benson Leung <bleung@...omium.org>,
        Olof Johansson <olof@...om.net>
Subject: Re: [PATCH v5 04/12] PM / devfreq: Add struct devfreq_policy

Hi,

On 2018년 07월 04일 08:46, Matthias Kaehlcke wrote:
> Move variables related with devfreq policy changes from struct devfreq
> to the new struct devfreq_policy and add a policy field to struct devfreq.
> 
> The following variables are moved:
> 
> df->min/max_freq           =>   p->user.min/max_freq
> df->scaling_min/max_freq   =>   p->devinfo.min/max_freq
> df->governor               =>   p->governor
> df->governor_name          =>   p->governor_name
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> Reviewed-by: Brian Norris <briannorris@...omium.org>
> ---
> Changes in v5:
> - none
> 
> Changes in v4:
> - added 'Reviewed-by: Brian Norris <briannorris@...omium.org>' tag
> 
> Changes in v3:
> - none
> 
> Changes in v2:
> - performance, powersave and simpleondemand governors don't need changes
>   with "PM / devfreq: Don't adjust to user limits in governors"
> - formatting fixes
> ---
>  drivers/devfreq/devfreq.c          | 137 ++++++++++++++++-------------
>  drivers/devfreq/governor_passive.c |   4 +-
>  include/linux/devfreq.h            |  38 +++++---
>  3 files changed, 103 insertions(+), 76 deletions(-)
> 

(skip)

>  
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 3bc29acbd54e..e0987c749ec2 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -99,12 +99,12 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>  {
>  	int ret;
>  
> -	if (!devfreq->governor)
> +	if (!devfreq->policy.governor)
>  		return -EINVAL;
>  
>  	mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
>  
> -	ret = devfreq->governor->get_target_freq(devfreq, &freq);
> +	ret = devfreq->policy.governor->get_target_freq(devfreq, &freq);
>  	if (ret < 0)
>  		goto out;
>  
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 3aae5b3af87c..9bf23b976f4d 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -109,6 +109,30 @@ struct devfreq_dev_profile {
>  	unsigned int max_state;
>  };
>  
> +/**
> + * struct devfreq_freq_limits - Devfreq frequency limits
> + * @min_freq:	minimum frequency
> + * @max_freq:	maximum frequency
> + */
> +struct devfreq_freq_limits {
> +	unsigned long min_freq;
> +	unsigned long max_freq;
> +};
> +
> +/**
> + * struct devfreq_policy - Devfreq policy
> + * @user:	frequency limits requested by the user
> + * @devinfo:	frequency limits of the device (available OPPs)
> + * @governor:	method how to choose frequency based on the usage.

nitpick. remove '.' on the end of line.

> + * @governor_name:	devfreq governor name for use with this devfreq
> + */
> +struct devfreq_policy {
> +	struct devfreq_freq_limits user;
> +	struct devfreq_freq_limits devinfo;
> +	const struct devfreq_governor *governor;
> +	char governor_name[DEVFREQ_NAME_LEN];
> +};
> +
>  /**
>   * struct devfreq - Device devfreq structure
>   * @node:	list node - contains the devices with devfreq that have been
> @@ -117,8 +141,6 @@ struct devfreq_dev_profile {
>   * @dev:	device registered by devfreq class. dev.parent is the device
>   *		using devfreq.
>   * @profile:	device-specific devfreq profile
> - * @governor:	method how to choose frequency based on the usage.
> - * @governor_name:	devfreq governor name for use with this devfreq
>   * @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.
> @@ -126,10 +148,7 @@ struct devfreq_dev_profile {
>   * @previous_freq:	previously configured frequency value.
>   * @data:	Private data of the governor. The devfreq framework does not
>   *		touch this.
> - * @min_freq:	Limit minimum frequency requested by user (0: none)
> - * @max_freq:	Limit maximum frequency requested by user (0: none)
> - * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
> - * @scaling_max_freq:	Limit maximum frequency requested by OPP interface
> + * @policy:		Policy for frequency adjustments

The devfreq_policy contains the range of frequency and governor information.
But, this description focus on the frequency. You need to explain the more
correct description of 'policy'.

>   * @stop_polling:	 devfreq polling status of a device.
>   * @total_trans:	Number of devfreq transitions
>   * @trans_table:	Statistics of devfreq transitions
> @@ -151,8 +170,6 @@ struct devfreq {
>  	struct mutex lock;
>  	struct device dev;
>  	struct devfreq_dev_profile *profile;
> -	const struct devfreq_governor *governor;
> -	char governor_name[DEVFREQ_NAME_LEN];
>  	struct notifier_block nb;
>  	struct delayed_work work;
>  
> @@ -161,10 +178,7 @@ struct devfreq {
>  
>  	void *data; /* private data for governors */
>  
> -	unsigned long min_freq;
> -	unsigned long max_freq;
> -	unsigned long scaling_min_freq;
> -	unsigned long scaling_max_freq;
> +	struct devfreq_policy policy;

I recommend that you better to move under 'struct devfreq_dev_profile'
as following:
	
	struct devfreq_dev_profile *profile;
	struct devfreq_policy policy;


>  	bool stop_polling;
>  
>  	/* information for device frequency transition */
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics