linux-kernel - Re: [PATCH] ARM: dts: exynos: Use thermal fuse value for thermal zone 0 on Exynos5420

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Message-ID: <CAJKOXPeVLNRCWcWMT_subo2VRXdS1147MjFNCeGot8DpqguVNg@mail.gmail.com>
Date:   Mon, 13 Feb 2017 13:59:45 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Kukjin Kim <kgene@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Willy WOLFF <willy.mh.wolff@...il.com>
Subject: Re: [PATCH] ARM: dts: exynos: Use thermal fuse value for thermal zone
 0 on Exynos5420

On Mon, Feb 13, 2017 at 1:38 PM, Anand Moon <linux.amoon@...il.com> wrote:
> Hi Krzysztof,
>
>
>
> On 12 February 2017 at 01:44, Krzysztof Kozlowski <krzk@...nel.org> wrote:
>> In Odroid XU3 Lite board, the temperature levels reported for thermal
>> zone 0 were weird. In warm room:
>>         /sys/class/thermal/thermal_zone0/temp:32000
>>         /sys/class/thermal/thermal_zone1/temp:51000
>>         /sys/class/thermal/thermal_zone2/temp:55000
>>         /sys/class/thermal/thermal_zone3/temp:54000
>>         /sys/class/thermal/thermal_zone4/temp:51000
>>
>> Sometimes after booting the value was even equal to ambient temperature
>> which is highly unlikely to be a real temperature of sensor in SoC.
>>
>> The thermal sensor's calibration (trimming) is based on fused values.
>> In case of the board above, the fused values are: 35, 52, 43, 58 and 43
>> (corresponding to each TMU device).  However driver defined a minimum value
>> for fused data as 40 and for smaller values it was using a hard-coded 55
>> instead.  This lead to mapping data from sensor to wrong temperatures
>> for thermal zone 0.
>>
>> Various vendor 3.10 trees (Hardkernel's based on Samsung LSI, Artik 10)
>> do not impose any limits on fused values.  Since we do not have any
>> knowledge about these limits, use 0 as a minimum accepted fused value.
>> This should essentially allow accepting any reasonable fused value thus
>> behaving like vendor driver.
>>
>
> On HK following values are define in drivers/thermal/exynos_thermal.c
>
> #define EFUSE_MIN_VALUE                         40
> #define EFUSE_MAX_VALUE                         100

Are they being used?

Best regards,
Krzysztof