linux-kernel - Re: [PATCH v2 07/15] Documentation: ABI: testing: mt6370: Add ADC sysfs guideline

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Date:   Mon, 20 Jun 2022 19:35:00 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     ChiaEn Wu <peterwu.pub@...il.com>
Cc:     lars@...afoo.de, matthias.bgg@...il.com, lee.jones@...aro.org,
        Daniel Thompson <daniel.thompson@...aro.org>,
        jingoohan1@...il.com, pavel@....cz, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-fbdev@...r.kernel.org,
        szunichen@...il.com, ChiaEn Wu <chiaen_wu@...htek.com>
Subject: Re: [PATCH v2 07/15] Documentation: ABI: testing: mt6370: Add ADC
 sysfs guideline

On Mon, 20 Jun 2022 14:00:43 +0800
ChiaEn Wu <peterwu.pub@...il.com> wrote:

> Hi Jonathan,
> 
> Thanks for your helpful comments, and I have some questions want to
> ask you below.
> 
> Jonathan Cameron <jic23@...nel.org> 於 2022年6月18日 週六 晚上11:39寫道：
> >
> > On Mon, 13 Jun 2022 19:11:38 +0800
> > ChiaEn Wu <peterwu.pub@...il.com> wrote:
> >  
> > > From: ChiaEn Wu <chiaen_wu@...htek.com>
> > >
> > > Add ABI documentation for mt6370 non-standard ADC sysfs interfaces.
> > >
> > > Signed-off-by: ChiaEn Wu <chiaen_wu@...htek.com>
> > > ---
> > >  .../ABI/testing/sysfs-bus-iio-adc-mt6370      | 36 +++++++++++++++++++
> > >  1 file changed, 36 insertions(+)
> > >  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-mt6370
> > >
> > > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-mt6370 b/Documentation/ABI/testing/sysfs-bus-iio-adc-mt6370
> > > new file mode 100644
> > > index 000000000000..039b3381176a
> > > --- /dev/null
> > > +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-mt6370
> > > @@ -0,0 +1,36 @@
> > > +What:                /sys/bus/iio/devices/iio:deviceX/in_voltage0_raw  
> >
> > Unfortunately the kernel documentation build scripts do no support duplicating
> > standard ABI for particular devices so as to provide more information.
> > Hence you can't have anything in this file.
> >  
> 
> I want to confirm with you again,
> because my ABI file duplicates with standard sysfs-bus-iio (voltage,
> current, and temperature channels),
> Should I just remove this ABI file and modify the code of mt6370-adc
> to meet your expectations??

yes.

> 
> >  
> > > +KernelVersion:       5.18
> > > +Contact:     chiaen_wu@...htek.com
> > > +Description:
> > > +             Indicated MT6370 VBUS ADC with lower accuracy(+-75mA)  
> > Curious though, voltage with a mA accuracy range?  
> 
> Yes, this description is based on the data sheet.

Weird :) 

> 
> > This scale should be presented directly to userspace anyway so no need
> > for this doc.
> >  
> > > +             higher measure range(1~22V)
> > > +             Calculating with scale returns voltage in uV  
> >
> > No. All channels return in mV. That's the ABI requirement as
> > in sysfs-bus-iio and we cannot vary if for particular drivers.  If we did
> > no generic tooling would work.  
> 
> Ok, I got it!
> 
> >  
> > > +
> > > +What:                /sys/bus/iio/devices/iio:deviceX/in_voltage1_raw
> > > +KernelVersion:       5.18
> > > +Contact:     chiaen_wu@...htek.com
> > > +Description:
> > > +             Indicated MT6370 VBUS ADC with higher accuracy(+-30mA)
> > > +             lower measure range(1~9.76V)
> > > +             Calculating with scale offset returns voltage in uV
> > > +
> > > +What:                /sys/bus/iio/devices/iio:deviceX/in_voltage4_raw
> > > +KernelVersion:       5.18
> > > +Contact:     chiaen_wu@...htek.com
> > > +Description:
> > > +             Indicated MT6370 TS_BAT ADC
> > > +             Calculating with scale returns voltage in uV
> > > +
> > > +What:                /sys/bus/iio/devices/iio:deviceX/in_voltage7_raw
> > > +KernelVersion:       5.18
> > > +Contact:     chiaen_wu@...htek.com
> > > +Description:
> > > +             Indicated MT6370 CHG_VDDP ADC
> > > +             Calculating with scale returns voltage in mV
> > > +
> > > +What:                /sys/bus/iio/devices/iio:deviceX/in_temp8_raw
> > > +KernelVersion:       5.18
> > > +Contact:     chiaen_wu@...htek.com
> > > +Description:
> > > +             Indicated MT6370 IC junction temperature
> > > +             Calculating with scale and offset returns temperature in degree  
> 
> Shall I modify the scale of temperature to milli degrees in
> mt6370-adc.c and remove this item??

yes.

Thanks,

Jonathan

> 
> >  
> 
> Best regards,
> ChiaEn Wu