linux-kernel - Re: [PATCH 02/14] thermal: exynos: Propagate error value from tmu

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Date:   Mon, 16 Apr 2018 14:41:48 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     Eduardo Valentin <edubezval@...il.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH 02/14] thermal: exynos: Propagate error value from
 tmu_read()

On 16/04/2018 14:35, Bartlomiej Zolnierkiewicz wrote:
> On Monday, April 16, 2018 02:16:56 PM Daniel Lezcano wrote:
>> On 16/04/2018 12:11, Bartlomiej Zolnierkiewicz wrote:
>>> From: Marek Szyprowski <m.szyprowski@...sung.com>
>>>
>>> tmu_read() in case of Exynos4210 might return error for out of bound
>>> values. Current code ignores such value, what leads to reporting critical
>>> temperature value. Add proper error code propagation to exynos_get_temp()
>>> function.
>>
>> For me the comment in the function exynos4210_tmu_read
>>
>> /* "temp_code" should range between 75 and 175 */
>>
>> ... is strange. I would double check this assertion before dealing with
>> the error value.
> 
> static int exynos4210_tmu_read(struct exynos_tmu_data *data)
> {
> 	int ret = readb(data->base + EXYNOS_TMU_REG_CURRENT_TEMP);
> 
> 	/* "temp_code" should range between 75 and 175 */
> 	return (ret < 75 || ret > 175) ? -ENODATA : ret;
> }
> 

But I don't get why it *should* ?

Shouldn't be the same with the 4412, it seems having the same sensor, no?


> The value returned by Exynos4210 hardware should be > 75 && < 175 and
> it is later used as the "temp_code" parameter for code_to_temp():
> 
> static int code_to_temp(struct exynos_tmu_data *data, u16 temp_code)
> {
> 	if (data->cal_type == TYPE_ONE_POINT_TRIMMING)
> 		return temp_code - data->temp_error1 + EXYNOS_FIRST_POINT_TRIM;
> 
> 	return (temp_code - data->temp_error1) *
> 		(EXYNOS_SECOND_POINT_TRIM - EXYNOS_FIRST_POINT_TRIM) /
> 		(data->temp_error2 - data->temp_error1) +
> 		EXYNOS_FIRST_POINT_TRIM;
> }
> 
> so after the current fix the code finally matches the comment.
> 
>>> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
>>> CC: stable@...r.kernel.org # v4.6+
>>> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
>>> ---
>>>  drivers/thermal/samsung/exynos_tmu.c | 9 +++++++--
>>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
>>> index 986cbd0..ac83f72 100644
>>> --- a/drivers/thermal/samsung/exynos_tmu.c
>>> +++ b/drivers/thermal/samsung/exynos_tmu.c
>>> @@ -892,6 +892,7 @@ static void exynos7_tmu_control(struct platform_device *pdev, bool on)
>>>  static int exynos_get_temp(void *p, int *temp)
>>>  {
>>>  	struct exynos_tmu_data *data = p;
>>> +	int value, ret = 0;
>>>  
>>>  	if (!data || !data->tmu_read || !data->enabled)
>>>  		return -EINVAL;
>>> @@ -899,12 +900,16 @@ static int exynos_get_temp(void *p, int *temp)
>>>  	mutex_lock(&data->lock);
>>>  	clk_enable(data->clk);
>>>  
>>> -	*temp = code_to_temp(data, data->tmu_read(data)) * MCELSIUS;
>>> +	value = data->tmu_read(data);
>>> +	if (value < 0)
>>> +		ret = value;
>>> +	else
>>> +		*temp = code_to_temp(data, value) * MCELSIUS;
>>>  
>>>  	clk_disable(data->clk);
>>>  	mutex_unlock(&data->lock);
>>>  
>>> -	return 0;
>>> +	return ret;
>>>  }
>>>  
>>>  #ifdef CONFIG_THERMAL_EMULATION
> 
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
> 


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