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

From: Anand Moon <linux.amoon@gmail.com>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Zhang Rui <rui.zhang@intel.com>,
	Eduardo Valentin <edubezval@gmail.com>,
	Kukjin Kim <kgene@kernel.org>,
	Javier Martinez Canillas <javier@osg.samsung.com>,
	Linux PM list <linux-pm@vger.kernel.org>,
	"linux-samsung-soc@vger.kernel.org" 
	<linux-samsung-soc@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	devicetree <devicetree@vger.kernel.org>,
	Willy WOLFF <willy.mh.wolff@gmail.com>
Subject: Re: [PATCH] ARM: dts: exynos: Use thermal fuse value for thermal zone 0 on Exynos5420
Date: Mon, 13 Feb 2017 17:08:36 +0530	[thread overview]
Message-ID: <CANAwSgSJRv6XGKvysbw+cXYyVUEcNyGv=6tYSWsvOn42dX5f1w@mail.gmail.com> (raw)
In-Reply-To: <20170211201456.27974-1-krzk@kernel.org>

Hi Krzysztof,

On 12 February 2017 at 01:44, Krzysztof Kozlowski <krzk@kernel.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

> The exynos5420-tmu-sensor-conf.dtsi is copied directly from existing
> exynso4412 with one change - the samsung,tmu_min_efuse_value.
>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
>
> ---

Best Regards
-Anand