linux-kernel - Re: [PATCH v4 06/10] thermal: rockchip: consistently use int for temperatures

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Message-ID: <20151202183851.GA91131@google.com>
Date:	Wed, 2 Dec 2015 10:38:51 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Caesar Wang <wxt@...k-chips.com>
Cc:	Heiko Stuebner <heiko@...ech.de>,
	Eduardo Valentin <edubezval@...il.com>, lkp@...el.com,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-rockchip@...ts.infradead.org,
	Zhang Rui <rui.zhang@...el.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 06/10] thermal: rockchip: consistently use int for
 temperatures

Hi Caesar,

On Mon, Nov 09, 2015 at 12:48:58PM +0800, Caesar Wang wrote:
> As Temperature is currently represented as int not long in the thermal
> framework since use int intead of unsigned long/long to represent
> temperature to avoid bogus overheat detection when negative temperature
> reported.
> 
> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
> 
> ---
> 
> Changes in v4:
> - fix the warning from the print message.
> 
> Changes in v3:
> - As the Patch v2 comments, Add a new patch to fix it.
> 
> Changes in v2: None
> Changes in v1: None
> 
>  drivers/thermal/rockchip_thermal.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/thermal/rockchip_thermal.c b/drivers/thermal/rockchip_thermal.c
> index 7c5b784..73d47f8 100644
> --- a/drivers/thermal/rockchip_thermal.c
> +++ b/drivers/thermal/rockchip_thermal.c
> @@ -88,7 +88,7 @@ struct rockchip_tsadc_chip {
>  	int chn_num;
>  
>  	/* The hardware-controlled tshut property */
> -	long tshut_temp;
> +	int tshut_temp;
>  	enum tshut_mode tshut_mode;
>  	enum tshut_polarity tshut_polarity;
>  

...

> @@ -126,7 +126,7 @@ struct rockchip_thermal_data {
>  
>  	void __iomem *regs;
>  
> -	long tshut_temp;
> +	int tshut_temp;

FYI, this change is triggering a new warning in Coverity, below:

>  	enum tshut_mode tshut_mode;
>  	enum tshut_polarity tshut_polarity;
>  };

...

> @@ -477,7 +477,7 @@ static int rockchip_configure_from_dt(struct device *dev,
>  	}
>  
>  	if (thermal->tshut_temp > INT_MAX) {

     CID 1341498:  Integer handling issues  (CONSTANT_EXPRESSION_RESULT)
     "thermal->tshut_temp > 2147483647 /* (int)(~0U >> 1) */" is always false regardless of the values of its operands. This occurs as the logical operand of if.

I don't think this condition is even useful any more, so maybe we should
just kill the 'if' block.

> -		dev_err(dev, "Invalid tshut temperature specified: %ld\n",
> +		dev_err(dev, "Invalid tshut temperature specified: %d\n",
>  			thermal->tshut_temp);
>  		return -ERANGE;
>  	}

Brian
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