Re: [PATCH v8 4/5] rtc: mt6397: Add support for the MediaTek MT6358 RTC

[Ran Bi]

Hi,

On Wed, 2020-03-04 at 20:59 +0800, Nicolas Boichat wrote:
> Hi,
> 
> On Mon, Feb 17, 2020 at 11:52 AM Ran Bi <ran.bi@xxxxxxxxxxxx> wrote:
> >
> > On Tue, 2020-02-04 at 00:50 +0800, Yingjoe Chen wrote:
> > > > diff --git a/include/linux/mfd/mt6397/rtc.h b/include/linux/mfd/mt6397/rtc.h
> > > > index f84b916..fffe34a 100644
> > > > --- a/include/linux/mfd/mt6397/rtc.h
> > > > +++ b/include/linux/mfd/mt6397/rtc.h
> > > > @@ -18,7 +18,8 @@
> > > >  #define RTC_BBPU_CBUSY         BIT(6)
> > > >  #define RTC_BBPU_KEY            (0x43 << 8)
> > > >
> > > > -#define RTC_WRTGR              0x003c
> > > > +#define RTC_WRTGR_MT6358       0x3a
> > > > +#define RTC_WRTGR_MT6397       0x3c
> > > >
> > > >  #define RTC_IRQ_STA            0x0002
> > > >  #define RTC_IRQ_STA_AL         BIT(0)
> > > > @@ -57,6 +58,10 @@
> > > >  #define MTK_RTC_POLL_DELAY_US  10
> > > >  #define MTK_RTC_POLL_TIMEOUT   (jiffies_to_usecs(HZ))
> > > >
> > > > +struct mtk_rtc_data {
> > > > +   u32                     wrtgr;
> > > > +};
> > > > +
> > > >  struct mt6397_rtc {
> > > >     struct device           *dev;
> > > >     struct rtc_device       *rtc_dev;
> > > > @@ -66,6 +71,15 @@ struct mt6397_rtc {
> > > >     struct regmap           *regmap;
> > > >     int                     irq;
> > > >     u32                     addr_base;
> > > > +   const struct mtk_rtc_data *data;
> > > > +};
> > > > +
> > > > +static const struct mtk_rtc_data mt6358_rtc_data = {
> > > > +   .wrtgr = RTC_WRTGR_MT6358,
> > > > +};
> > > > +
> > > > +static const struct mtk_rtc_data mt6397_rtc_data = {
> > > > +   .wrtgr = RTC_WRTGR_MT6397,
> > > >  };
> > >
> > > Hi,
> > >
> > > Putting these in header file doesn't looks right to me.
> > > Who need this? can you move them back to rtc-mt6397.c?
> > > Joe.C
> > >
> >
> > This could also effect kernel/drivers/power/reset/mt6323-poweroff.c
> > which using same region of RTC registers.
> > There are 2 ways of modification:
> > 1. kernel/drivers/rtc/rtc-mt6397.c implement do_pwroff function and
> > export to mt6323-poweroff.c
> > 2. Just modify mt6323-poweroff.c file to compatible this patch. I mean
> > using RTC_WRTGR_MT6397 to replace RTC_WRTGR. Or modify mt6323-poweroff.c
> > like rtc-mt6397.c
> 
> Oh, I see, so basically both rtc-mt6397.c and mt6323-poweroff.c need
> to know at what offset RTC_WRTGR actually is. Correct?
> 

Yes, you are right both drivers need to know RTC_WRTGR offset. Offsets
of other registers are the same.

> Is there any plan to have mt6323-poweroff.c support any of the other
> PMICs (not just MT6323?)?
> 

Currently, we don't have a plan to let mt6323-poweroff.c support other
PMICs. Because other PMICs like mt6397 and mt6358 could using
arm-trust-firmware PSCI power off flow instead. mt6323-poweroff.c was
prepared for platform without arm-trust-firmware.

> a. If not, I'd just add:
> #define RTC_WRTGR_MT6323 RTC_WRTGR_MT6397
> in rtc.h, for added clarity, use that in mt6323-poweroff.c
> (s/RTC_WRTGR/RTC_WRTGR_MT6323/), and be done with it.
> 

I would just change RTC_WRTGR to RTC_WRTGR_MT6397 in mt6323-poweroff.c
at next patchset.

> Actually, even if there's a plan, you can go ahead with this simpler
> solution for now, and fix later when the issue comes up.
> 
> b. If you ever want to support multiple PMICs with mt6323-poweroff.c,
> you'd need that offset for 2 different sub-devices under the same mfd,
> so the matching logic belongs in the main mfd device, not in
> rtc/poweroff driver.
> 
> So I'd move the matching logic in drivers/mfd/mt6397-core.c, and add
> rtc_wrtgr offset (or a full _data structure) to `struct mt6397_chip`,
> or, probably better, add a IORESOURCE_REG to the matching resources to
> specify the offset (that's what drivers/mfd/88pm860x-core.c seems to
> be doing, for example).
> 
> And then mt6323-poweroff.c should probably be renamed to mt6397-poweroff.c.
> 
> (actually, looking at this, I'm even questioning if mt6323-poweroff.c
> should even exist, and if you should just fold it into rtc-mt6397.c?
> Since they use the same registers?)
> 

mt6323-poweroff.c which hijack pm_power_off pointer is only for platform
without arm-trust-firmware. This is the reason I am considering
mt6323-poweroff.c should not be folded into rtc-mt6397.c.

> Hope this makes sense?
> 
> Best,

Thanks for your suggestions.

Best,