linux-kernel - Re: [PATCH v1 2/3] iio: adc: meson: consistently use bool/enum in struct meson_sar_adc

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Message-ID: <CAFBinCBxsv92t_B_T3vBDJJ1K5BwUbV=as6sy-KyQYz+2jur2g@mail.gmail.com>
Date: Tue, 24 Dec 2024 15:37:00 +0100
From: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To: George Stark <gnstark@...utedevices.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	neil.armstrong@...aro.org, lars@...afoo.de, jic23@...nel.org, 
	linux-amlogic@...ts.infradead.org, 
	"kernel@...utedevices.com" <kernel@...utedevices.com>, Xingyu Chen <xingyu.chen@...ogic.com>, 
	Zelong Dong <zelong.dong@...ogic.com>
Subject: Re: [PATCH v1 2/3] iio: adc: meson: consistently use bool/enum in
 struct meson_sar_adc_param

Hi George,

On Tue, Mar 26, 2024 at 1:41 AM George Stark <gnstark@...utedevices.com> wrote:
[...]
> >   enum meson_sar_adc_avg_mode {
> >       NO_AVERAGING = 0x0,
> >       MEAN_AVERAGING = 0x1,
> > @@ -321,13 +326,13 @@ struct meson_sar_adc_param {
> >       u8                                      temperature_trimming_bits;
> >       unsigned int                            temperature_multiplier;
> >       unsigned int                            temperature_divider;
> > -     u8                                      disable_ring_counter;
> > +     bool                                    disable_ring_counter;
> >       bool                                    has_reg11;
> >       bool                                    has_vref_select;
> > -     u8                                      vref_select;
> > -     u8                                      cmv_select;
> > -     u8                                      adc_eoc;
>
>
> The reason to choose u8 type over bool was that those are not actually
> bool values but direct values of hw register bits. We have little
> information about real meaning of these bits so it won't help much to
> add bool layer and keep real values in the init code instead of param
> section (adc_eoc, cmv_select).
> bool disable_ring_counter will look deceptive too because it doesn't
> say whether disable ring_counter or not (we always disable it) but
> how to disable it (write 0 or 1)
Do you have any contact at Amlogic that can help explain the purpose
of these bits?
I tried reaching out to my contact off-list but did not get any answers.

I also have more questions about the SARADC IP block on the GXLX SoC.
We (Christian and I) have a patch prepared to fix audio (or rather the
MPLL clocks) on the GXLX SoC (see [0]). Unfortunately there seems to
be nobody that's answering me with enough info so we can upstream that
patch.

So if you have any contact or insights into datasheets - please check
and see if you can provide information so we can improve the naming of
these bits and hopefully get GXLX SoC support fixed.

Also +Cc Xingyu Chen and Zelong Dong - I found your names in
downstream patches to the SARADC driver [1].


Thank you and best regards,
Martin


[0] https://lore.kernel.org/linux-amlogic/20240604055431.3313961-2-christianshewitt@gmail.com/
[1] https://github.com/khadas/linux/commit/13321d23231a7a4d08f4fefebcef11b379475a37