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Message-ID: <20161213154304.k3v2nwwqinp64puj@lukather>
Date: Tue, 13 Dec 2016 16:43:04 +0100
From: Maxime Ripard <maxime.ripard@...e-electrons.com>
To: Quentin Schulz <quentin.schulz@...e-electrons.com>
Cc: linux@...linux.org.uk, wens@...e.org, jic23@...nel.org,
knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
lee.jones@...aro.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
antoine.tenart@...e-electrons.com,
thomas.petazzoni@...e-electrons.com
Subject: Re: [PATCH v9 1/3] ARM: sunxi_defconfig: Add CONFIG_THERMAL_OF
On Tue, Dec 13, 2016 at 03:33:30PM +0100, Quentin Schulz wrote:
> This enables CONFIG_THERMAL_OF by default for sunxi_defconfig. It is
> required to get Allwinner SoCs' temperature from the GPADC driver.
>
> The Allwinner SoCs all have an ADC that can also act as a touchscreen
> controller and a thermal sensor. The first four channels can be used
> either for the ADC or the touchscreen and the fifth channel is used for
> the thermal sensor.
>
> The thermal sensor requires the IP to be in touchscreen mode to return
> correct values. Therefore, if the user is continuously reading the ADC
> channel(s), the thermal framework in which the thermal sensor is
> registered will switch the IP in touchscreen mode to get a temperature
> value and requires a delay of 100ms (because of the mode switching),
> then the ADC will switch back to ADC mode and requires also a delay of
> 100ms. If the ADC readings are critical to user and the SoC temperature
> is not, the GPADC driver is capable of not registering the thermal
> sensor in the thermal framework and thus, "quicken" the ADC readings. In
> most use cases, the SoC temperature is more critical (for cpu throttling
> for example or activating cooling devices) than ADC readings, thus it is
> now enabled by default.
>
> Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
Applied, thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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