linux-kernel - Re: [PATCH] iio: adc: Add scaling support to exynos adc driver

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Date:   Mon, 11 May 2020 09:42:32 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Jonathan Bakker <xc-racer2@...e.ca>, knaack.h@....de,
        lars@...afoo.de, pmeerw@...erw.net, kgene@...nel.org,
        cw00.choi@...sung.com, kstewart@...uxfoundation.org,
        mpe@...erman.id.au, m.szyprowski@...sung.com, swboyd@...omium.org,
        tglx@...utronix.de, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: adc: Add scaling support to exynos adc driver

On Sun, May 10, 2020 at 11:24:17AM +0100, Jonathan Cameron wrote:
> On Fri,  8 May 2020 14:14:00 -0700
> Jonathan Bakker <xc-racer2@...e.ca> wrote:
> 
> > Currently the driver only exposes the raw counts.  As we
> > have the regulator voltage and the maximum value (stored in
> > the data mask), we can trivially produce a scaling fraction
> > of voltage / max value.
> > 
> > This assumes that the regulator voltage is in fact the max
> > voltage, which appears to be the case for all mainline dts
> > and cross referenced with the public Exynos4412 and S5PV210
> > datasheets.
> > 
> > Signed-off-by: Jonathan Bakker <xc-racer2@...e.ca>
> 
> Seems reasonable to me. I'd like an exynos Ack though before applying.


It's correct, at least with ARMv7 Exynos datasheets

The few ARMv8 Exynos chips are silent about the voltage levels. The
Exynos 7 DTS board in mainline kernel does not have regulator but it
looks clearly like mistake.

I think they behave the same, so for Exynos:
Reviewed-by: Krzysztof Kozlowski <krzk@...nel.org>

Best regards,
Krzysztof

> thanks,
> 
> Jonathan
> 
>