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Subject: Re: [PATCH v5 1/2] PM / devfreq: Add governor feature flag
To:     Chanwoo Choi <cw00.choi@samsung.com>, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org
Cc:     lukasz.luba@arm.com, enric.balletbo@collabora.com,
        hl@rock-chips.com, thierry.reding@gmail.com, jonathanh@nvidia.com,
        abel.vesa@nxp.com, k.konieczny@samsung.com,
        b.zolnierkie@samsung.com, chanwoo@kernel.org,
        myungjoo.ham@samsung.com, kyungmin.park@samsung.com
References: <20201023102632.740-1-cw00.choi@samsung.com>
 <CGME20201023101246epcas1p423f0444201300830fd63f33748dd8952@epcas1p4.samsung.com>
 <20201023102632.740-2-cw00.choi@samsung.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <622cd840-0b09-e377-fbff-dd3e8ef0ff4e@gmail.com>
Date:   Sun, 25 Oct 2020 19:29:32 +0300
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23.10.2020 13:26, 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_FLAG_IMMUTABLE
> and set it to flag of passive governor.
> 
> [Definition for governor flag]
> - DEVFREQ_GOV_FLAG_IMMUTABLE
>   : If immutable flag is set, governor is never changeable to other governors.
> - DEVFREQ_GOV_FLAG_IRQ_DRIVEN
>   : Devfreq core won't schedule polling work for this governor if value is set.
> 
> [Table of governor flag for devfreq governors]
> ------------------------------------------------------------------------------
>                       | simple    | perfor | power | user | passive | tegra30
> 		      | ondemand  | mance  | save  | space|         |
> ------------------------------------------------------------------------------
> immutable             | X         | X      | X     | X    | O       | O
> interrupt_driven      | X(polling)| X      | X     | X    | X       | O (irq)
> ------------------------------------------------------------------------------
> 
> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>