linux-kernel - Re: [PATCH 01/14] thermal: exynos: Reading temperature makes sense only when TMU is turned on

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Message-ID: <f7da04ae-da92-062e-1420-76df43700f29@linaro.org>
Date:   Mon, 16 Apr 2018 14:39:00 +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 01/14] thermal: exynos: Reading temperature makes sense
 only when TMU is turned on

On 16/04/2018 14:17, Bartlomiej Zolnierkiewicz wrote:
> On Monday, April 16, 2018 02:06:41 PM Daniel Lezcano wrote:
>> On 16/04/2018 12:11, Bartlomiej Zolnierkiewicz wrote:
>>> From: Marek Szyprowski <m.szyprowski@...sung.com>
>>>
>>> When thermal sensor is not yet enabled, reading temperature might return
>>> random value. This might even result in stopping system booting when such
>>> temperature is higher than the critical value. Fix this by checking if TMU
>>> has been actually enabled before reading the temperature.
>>>
>>> This change fixes booting of Exynos4210-based board with TMU enabled (for
>>> example Samsung Trats board), which was broken since v4.4 kernel release.
>>
>> Why not move the thermal_zone_of_sensor_register *after* initializing
>> the sensor ?
> 
> For initializing the sensor we need data obtained from
> therm_zone_of_sensor_register() so it cannot be easily
> done (especially since we also want the fix to be
> ported to -stable kernels). For more detailed description
> please see:
> 
> https://lkml.org/lkml/2018/4/10/376

I see, a chicken egg problem :/

Thanks for the pointer.


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