linux-kernel - Re: [PATCH v3 1/2] PM / devfreq: Add governor feature flag

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Date:   Mon, 19 Oct 2020 03:57:21 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Cc:     leonard.crestez@....com, lukasz.luba@....com,
        enric.balletbo@...labora.com, hl@...k-chips.com,
        thierry.reding@...il.com, jonathanh@...dia.com, abel.vesa@....com,
        k.konieczny@...sung.com, b.zolnierkie@...sung.com,
        chanwoo@...nel.org, myungjoo.ham@...sung.com,
        kyungmin.park@...sung.com
Subject: Re: [PATCH v3 1/2] PM / devfreq: Add governor feature flag

07.10.2020 08:07, Chanwoo Choi пишет:
> The devfreq governor is able to have the specific flag as follows
> in order to implement the specific feature. For example, devfreq allows
> user to change the governors on runtime via sysfs interface.
> But, if devfreq device uses 'passive' governor, don't allow user to change
> the governor. For this case, define the DEVFREQ_GOV_FLAT_IMMUTABLE

s/DEVFREQ_GOV_FLAT/DEVFREQ_GOV_FLAG/

...
>  /**
>   * struct devfreq_governor - Devfreq policy governor
>   * @node:		list node - contains registered devfreq governors
>   * @name:		Governor's name
> - * @immutable:		Immutable flag for governor. If the value is 1,
> - *			this governor is never changeable to other governor.
> - * @interrupt_driven:	Devfreq core won't schedule polling work for this
> - *			governor if value is set to 1.
> + * @flag:		Governor's feature flag
>   * @get_target_freq:	Returns desired operating frequency for the device.
>   *			Basically, get_target_freq will run
>   *			devfreq_dev_profile.get_dev_status() to get the
> @@ -50,8 +57,7 @@ struct devfreq_governor {
>  	struct list_head node;
>  
>  	const char name[DEVFREQ_NAME_LEN];
> -	const unsigned int immutable;
> -	const unsigned int interrupt_driven;
> +	const u64 flag;
A plural form of flag(s) is more common, IMO.

It's also possible to use a single bit:1 for the struct members. Thus,
could you please explain what are the benefits of the "flag"?