Re: [PATCH stable v4.9+] ARM: dts: exynos: Do not ignore real-world fuse values for thermal zone 0 on Exynos5420

[Greg KH <greg@kroah.com>]

On Tue, Mar 12, 2019 at 01:26:03PM +0100, Krzysztof Kozlowski wrote:
> commit 28928a3ce142b2e4e5a7a0f067cefb41a3d2c3f9 upstream.
> 
> 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.
> 
> The exynos5420-tmu-sensor-conf.dtsi is copied directly from existing
> exynos4412 with one change - the samsung,tmu_min_efuse_value.
> 
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> Acked-by: Eduardo Valentin <edubezval@gmail.com>
> Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
> Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
> Reviewed-by: Anand Moon <linux.amoon@gmail.com>
> Tested-by: Anand Moon <linux.amoon@gmail.com>
> ---
>  arch/arm/boot/dts/exynos5420-tmu-sensor-conf.dtsi | 25 +++++++++++++++++++++++
>  arch/arm/boot/dts/exynos5420.dtsi                 | 10 ++++-----
>  2 files changed, 30 insertions(+), 5 deletions(-)
>  create mode 100644 arch/arm/boot/dts/exynos5420-tmu-sensor-conf.dtsi

Looks good, now queued up along with the 4.4.y version.

greg k-h