linux-kernel - Re: [PATCH v1 1/2] mfd: mt6397: Add new bit definitions for RTC

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Message-ID: <CAE7dp2rxfgj6FKoM-kesX8632t3AA7Lk5rC-uasyQUS2hQuUfQ@mail.gmail.com>
Date: Mon, 11 Aug 2025 15:21:25 +0400
From: Giorgi Tchankvetadze <giorgitchankvetadze1997@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: ot_shunxi.zhang@...iatek.com, Eddie Huang <eddie.huang@...iatek.com>, 
	Sean Wang <sean.wang@...iatek.com>, Alexandre Belloni <alexandre.belloni@...tlin.com>, 
	Matthias Brugger <matthias.bgg@...il.com>, Lee Jones <lee@...nel.org>, 
	linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
	linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	sirius.wang@...iatek.com, vince-wl.liu@...iatek.com, jh.hsu@...iatek.com
Subject: Re: [PATCH v1 1/2] mfd: mt6397: Add new bit definitions for RTC_BBPU register

Cc: Krzysztof Kozlowski <krzk@...nel.org>,
    linux-mediatek@...ts.infradead.org,
    linux-rtc@...r.kernel.org,
    linux-kernel@...r.kernel.org

Shunxi,

Can you confirm whether `RTC_BBPU_PWREN` (bit 0),
`RTC_BBPU_CLR` (bit 1) and `RTC_BBPU_RESET_AL` (bit 3) are documented
in the MT6397 datasheet (please cite section/page)? They look like
standard RTC controls (power enable, clear/reset, alarm reset) and
might be useful to include, but I agree with Krzysztof that adding
definitions with no users can accumulate technical debt.

Suggestion: either
- add the definitions when a driver actually needs them, or
- keep them now but add a short rationale in the commit message
  (datasheet reference + intended use) so future reviewers understand
  why they exist.

Also: please split cosmetic whitespace fixes (RTC_BBPU_KEY) into a
separate patch to make review/merge easier.

Thanks for the patch; I’m following the thread.

— Giorgi


On Mon, Aug 11, 2025 at 3:03 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> On 11/08/2025 10:15, ot_shunxi.zhang@...iatek.com wrote:
> > From: Shunxi Zhang <ot_shunxi.zhang@...iatek.com>
> >
> > This patch adds new bit definitions for the RTC_BBPU register in the
>
> Why? There is no user of these. Don't add useless defines.
>
> > mt6397 RTC header file. The following bit definitions are introduced:
>
> Hm?
>
> >
> > Signed-off-by: Shunxi Zhang <ot_shunxi.zhang@...iatek.com>
> > ---
> >  include/linux/mfd/mt6397/rtc.h | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/mfd/mt6397/rtc.h b/include/linux/mfd/mt6397/rtc.h
> > index 27883af44f87..001cef6b7302 100644
> > --- a/include/linux/mfd/mt6397/rtc.h
> > +++ b/include/linux/mfd/mt6397/rtc.h
> > @@ -15,8 +15,11 @@
> >  #include <linux/rtc.h>
> >
> >  #define RTC_BBPU               0x0000
> > +#define RTC_BBPU_PWREN         BIT(0)
> > +#define RTC_BBPU_CLR           BIT(1)
> > +#define RTC_BBPU_RESET_AL      BIT(3)
> >  #define RTC_BBPU_CBUSY         BIT(6)
> > -#define RTC_BBPU_KEY            (0x43 << 8)
> > +#define RTC_BBPU_KEY           (0x43 << 8)
>
>
> Why?
>
>
>
> Best regards,
> Krzysztof
>