[PATCH 1/3] iio: adc: sun4i-gpadc-iio: no temp sensor on R40

[Maxime Ripard]

On Fri, Nov 19, 2021 at 10:14:54PM +0300, Evgeny Boger wrote:
> R40 SoC has touchscreen controller also serving as general-purpose ADC.
> The hardware is very similar to A31, except that R40 has separate
> calibrated thermal sensor IP (handled by sun8i_thermal).
> 
> Despite the temperature sensor in the RTP is never mentioned in
> the R40 family user manuals, it appears to be working. However,
> it's not very useful as it lacks calibration data and there is another
> fully functioning temperature sensor anyway.
> 
> This patch disables the temperature sensor in RTP/GPADC IP on R40.
> 
> The reason for disabling the temperature sensor is that the IP
> needs to be switched back and forth between RTP and GPADC modes for
> temperature measurements. Not only this introduces delays, but it also
> disturbs external circuitry by injecting current into ADC inputs.
> 
> Signed-off-by: Evgeny Boger <boger at wirenboard.com>

Acked-by: Maxime Ripard <maxime at cerno.tech>

Maxime
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