linux-kernel - Re: [PATCH 08/13] thermal/drivers/hisi: Fix configuration register setting

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Date:   Sat, 2 Sep 2017 10:54:26 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     rui.zhang@...el.com, edubezval@...il.com, linux-pm@...r.kernel.org,
        kevin.wangtao@...aro.org, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 08/13] thermal/drivers/hisi: Fix configuration register
 setting

On Wed, Aug 30, 2017 at 10:47:32AM +0200, Daniel Lezcano wrote:
> The TEMP0_CFG configuration register contains different field to set up the
> temperature controller. However in the code, nothing prevents a setup to
> overwrite the previous one: eg. writing the hdak value overwrites the sensor
> selection, the sensor selection overwrites the hdak value.
> 
> In order to prevent such thing, use a regmap-like mechanism by reading the
> value before, set the corresponding bits and write the result.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
>  drivers/thermal/hisi_thermal.c | 30 +++++++++++++++++++++++++-----
>  1 file changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/thermal/hisi_thermal.c b/drivers/thermal/hisi_thermal.c
> index d77a938..3e03908 100644
> --- a/drivers/thermal/hisi_thermal.c
> +++ b/drivers/thermal/hisi_thermal.c
> @@ -132,19 +132,39 @@ static inline void hisi_thermal_enable(void __iomem *addr, int value)
>  	writel(value, addr + TEMP0_EN);
>  }
>  
> -static inline void hisi_thermal_sensor_select(void __iomem *addr, int sensor)
> +static inline int hisi_thermal_get_temperature(void __iomem *addr)
>  {
> -	writel((sensor << 12), addr + TEMP0_CFG);
> +	return hisi_thermal_step_to_temp(readl(addr + TEMP0_VALUE));
>  }
>  
> -static inline int hisi_thermal_get_temperature(void __iomem *addr)
> +/*
> + * Temperature configuration register - Sensor selection
> + *
> + * Bits [19:12]
> + *
> + * 0x0: local sensor (default)
> + * 0x1: remote sensor 1 (ACPU cluster 1)
> + * 0x2: remote sensor 2 (ACPU cluster 0)
> + * 0x3: remote sensor 3 (G3D)
> + */
> +static inline void hisi_thermal_sensor_select(void __iomem *addr, int sensor)
>  {
> -	return hisi_thermal_step_to_temp(readl(addr + TEMP0_VALUE));
> +	writel(readl(addr + TEMP0_CFG) | (sensor << 12), addr + TEMP0_CFG);

nitpick: maybe it's better to firstly clear related bits and then set
value?

>  }
>  
> +/*
> + * Temperature configuration register - Hdak conversion polling interval
> + *
> + * Bits [5:4]
> + *
> + * 0x0 :   0.768 ms
> + * 0x1 :   6.144 ms
> + * 0x2 :  49.152 ms
> + * 0x3 : 393.216 ms
> + */
>  static inline void hisi_thermal_hdak_set(void __iomem *addr, int value)
>  {
> -	writel(value, addr + TEMP0_CFG);
> +	writel(readl(addr + TEMP0_CFG) | (value << 4), addr + TEMP0_CFG);

Ditto.

>  }
>  
>  static long hisi_thermal_get_sensor_temp(struct hisi_thermal_data *data,
> -- 
> 2.7.4
>