Re: [PATCH v10 4/5] rtc: mt6397: Add support for the MediaTek MT6358 RTC

From: Lee Jones <lee.jones@linaro•org>
To: Ran Bi <ran.bi@mediatek•com>
Cc: Mark Rutland <mark.rutland@arm•com>,
	Alessandro Zummo <a.zummo@towertech•it>,
	Alexandre Belloni <alexandre.belloni@bootlin•com>,
	Nicolas Boichat <drinkcat@chromium•org>,
	srv_heupstream@mediatek•com,
	Frank Wunderlich <frank-w@public-files•de>,
	Josef Friedl <josef.friedl@speed•at>,
	linux-pm@vger•kernel.org, Sean Wang <sean.wang@mediatek•com>,
	Sebastian Reichel <sre@kernel•org>,
	linux-kernel@vger•kernel.org,
	Richard Fontana <rfontana@redhat•com>,
	devicetree@vger•kernel.org, Rob Herring <robh+dt@kernel•org>,
	linux-mediatek@lists•infradead.org,
	linux-arm-kernel@lists•infradead.org,
	Matthias Brugger <matthias.bgg@gmail•com>,
	Thomas Gleixner <tglx@linutronix•de>,
	Eddie Huang <eddie.huang@mediatek•com>,
	Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek•com>,
	linux-rtc@vger•kernel.org
Subject: Re: [PATCH v10 4/5] rtc: mt6397: Add support for the MediaTek MT6358 RTC
Date: Fri, 13 Mar 2020 07:22:30 +0000	[thread overview]
Message-ID: <20200313072230.GC3142@dell> (raw)
In-Reply-To: <1584003477.6269.8.camel@mhfsdcap03>

On Thu, 12 Mar 2020, Ran Bi wrote:

> On Thu, 2020-03-12 at 07:44 +0000, Lee Jones wrote:
> > On Wed, 11 Mar 2020, Hsin-Hsiung Wang wrote:
> > 
> > > From: Ran Bi <ran.bi@mediatek•com>
> > > 
> > > This add support for the MediaTek MT6358 RTC. Driver using
> > > compatible data to store different RTC_WRTGR address offset.
> > > This replace RTC_WRTGR to RTC_WRTGR_MT6323 in mt6323-poweroff
> > > driver which only needed by armv7 CPU without ATF.
> > > 
> > > Signed-off-by: Ran Bi <ran.bi@mediatek•com>
> > > Signed-off-by: Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek•com>
> > > ---
> > >  drivers/power/reset/mt6323-poweroff.c |  2 +-
> > >  drivers/rtc/rtc-mt6397.c              | 32 ++++++++++++++++++++++++--------
> > >  include/linux/mfd/mt6397/rtc.h        |  9 ++++++++-
> > >  3 files changed, 33 insertions(+), 10 deletions(-)
> > > 
> 
> <...>
> 
> > >  
> > >  #define RTC_IRQ_STA            0x0002
> > >  #define RTC_IRQ_STA_AL         BIT(0)
> > > @@ -65,6 +67,10 @@
> > >  #define MTK_RTC_POLL_DELAY_US  10
> > >  #define MTK_RTC_POLL_TIMEOUT   (jiffies_to_usecs(HZ))
> > >  
> > > +struct mtk_rtc_data {
> > > +	u32			wrtgr;
> > > +};
> > 
> > Do you expect to add more properties to this struct?
> > 
> > If not, it seems a bit overkill.
> > 
> 
> Yes, we would add more properties here in future patches.
> 
> > >  struct mt6397_rtc {
> > >  	struct device           *dev;
> > >  	struct rtc_device       *rtc_dev;
> > > @@ -74,6 +80,7 @@ struct mt6397_rtc {
> > >  	struct regmap           *regmap;
> > >  	int                     irq;
> > >  	u32                     addr_base;
> > > +	const struct mtk_rtc_data *data;
> > 
> > 'data' is a terrible variable name.
> > 
> > Why do you need to store this?
> > 
> > It's one variable which is used once AFAICT.
> 
> I would rename 'data' to 'config'.
> 
> This struct will be extended in future patches to achieve more PMIC chip
> compatibility.

On closer inspection, it looks like wrtgr (also not a great name for a
variable by the way) is a register address.  Is that correct?
Initially I thought it was a model number, which would have been a
suitable candidate for entry into OF .data.

However, describing register addresses in OF .data does not sound like
good practice.  It is usually used to identify a platform in the cases
where platforms cannot be otherwise dynamically interrogated for model
number via a register read.

Describing register maps via 'config' data is a slippery slope.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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