linux-kernel - Re: [PATCH v7 3/3] thermal: tegra: add get

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Message-ID: <bae5b0c3-3d7f-0b60-da96-730c7e8c4e5c@linaro.org>
Date:   Mon, 18 Feb 2019 11:27:34 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Wei Ni <wni@...dia.com>, edubezval@...il.com
Cc:     thierry.reding@...il.com, linux-tegra@...r.kernel.org,
        rui.zhang@...el.com, srikars@...dia.com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v7 3/3] thermal: tegra: add get_trend ops

On 03/01/2019 11:12, Wei Ni wrote:
> Add support for get_trend ops that allows soctherm
> sensors to be used with the step-wise governor.
> 
> Signed-off-by: Wei Ni <wni@...dia.com>
> ---
>  drivers/thermal/tegra/soctherm.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/thermal/tegra/soctherm.c b/drivers/thermal/tegra/soctherm.c
> index fd2703c0cfc5..864205af104b 100644
> --- a/drivers/thermal/tegra/soctherm.c
> +++ b/drivers/thermal/tegra/soctherm.c
> @@ -488,9 +488,43 @@ static int tegra_thermctl_set_trip_temp(void *data, int trip, int temp)
>  	return 0;
>  }
>  
> +static int tegra_thermctl_get_trend(void *data, int trip,
> +				    enum thermal_trend *trend)
> +{
> +	struct tegra_thermctl_zone *zone = data;
> +	struct thermal_zone_device *tz = zone->tz;
> +	int trip_temp, temp, last_temp, ret;
> +
> +	if (!tz)
> +		return -EINVAL;
> +
> +	ret = tz->ops->get_trip_temp(zone->tz, trip, &trip_temp);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&tz->lock);

No need to use the mutex here.

Why not ?

temp = READ_ONCE(tz->temperature);
last_temp = READ_ONCE(tz->last_temperature);

> +	temp = tz->temperature;
> +	last_temp = tz->last_temperature;
> +	mutex_unlock(&tz->lock);
> +
> +	if (temp > trip_temp) {
> +		if (temp >= last_temp)
> +			*trend = THERMAL_TREND_RAISING;
> +		else
> +			*trend = THERMAL_TREND_STABLE;
> +	} else if (temp < trip_temp) {
> +		*trend = THERMAL_TREND_DROPPING;
> +	} else {
> +		*trend = THERMAL_TREND_STABLE;
> +	}
> +
> +	return 0;
> +}
> +
>  static const struct thermal_zone_of_device_ops tegra_of_thermal_ops = {
>  	.get_temp = tegra_thermctl_get_temp,
>  	.set_trip_temp = tegra_thermctl_set_trip_temp,
> +	.get_trend = tegra_thermctl_get_trend,
>  };
>  
>  static int get_hot_temp(struct thermal_zone_device *tz, int *trip, int *temp)
> 


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