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Date:   Fri, 2 Dec 2022 17:06:56 +0000
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Di Shen <di.shen@unisoc.com>
Cc:     rafael@kernel.org, daniel.lezcano@linaro.org, amitk@kernel.org,
        rui.zhang@intel.com, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, xuewen.yan@unisoc.com
Subject: Re: [PATCH V2] thermal/of: Allow users to set governor for a thermal
 zone in DT
Message-ID: <Y4owsFhh7OWGwrbr@google.com>
References: <202212020239.CufwkKiR-lkp@intel.com>
 <20221202091111.1682-1-di.shen@unisoc.com>
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On Fri, Dec 02, 2022 at 05:11:11PM +0800, Di Shen wrote:
> The governor of all thermal zones can be initialized in
> thermal_zone_device_register_with_trips(), but it is always the
> def_governor, this means the governor of all thermal zones are
> the same.
> 
> Allow users to set governor for a specific thermal zone in DT, in
> this way, users can use different policies for thermal management.

There have been other attempts in the past of adding this to the
device tree (e.g. [1]), which were rejected since the DT should
describe the hardware, not policy. Userspace can configure thermal
zones to use a non-default governor through sysfs.

[1] https://lore.kernel.org/all/3b80853abb45a9e067cf7a16754b07bb67712457.1520274879.git.amit.kucheria@linaro.org/


> 
> Signed-off-by: Di Shen <di.shen@unisoc.com>
> ---
>  drivers/thermal/thermal_of.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> index d4b6335ace15..4a29ac3be2ac 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -355,6 +355,7 @@ static struct thermal_zone_params *thermal_of_parameters_init(struct device_node
>  	int coef[2];
>  	int ncoef = ARRAY_SIZE(coef);
>  	int prop, ret;
> +	const char *governor_name;
>  
>  	tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
>  	if (!tzp)
> @@ -365,6 +366,11 @@ static struct thermal_zone_params *thermal_of_parameters_init(struct device_node
>  	if (!of_property_read_u32(np, "sustainable-power", &prop))
>  		tzp->sustainable_power = prop;
>  
> +	if (!of_property_read_string(np, "policy", &governor_name)) {
> +		strncpy(tzp->governor_name, governor_name, THERMAL_NAME_LENGTH - 1);
> +		tzp->governor_name[THERMAL_NAME_LENGTH - 1] = '\0';
> +	}
> +
>  	/*
>  	 * For now, the thermal framework supports only one sensor per
>  	 * thermal zone. Thus, we are considering only the first two
> -- 
> 2.17.1
>