Re: [RFC PATCH v2 08/10] rtc: bd70528: Initial support for ROHM bd70528 RTC

[Guenter Roeck]

On 1/27/19 11:48 PM, Matti Vaittinen wrote:
> Thanks again Guenter,
>
> On Sat, Jan 26, 2019 at 08:30:24AM -0800, Guenter Roeck wrote:
> > On 1/25/19 3:05 AM, Matti Vaittinen wrote:
> > > +/*
> > > + * We read regs RTC_SEC => RTC_YEAR
> > > + * this struct is ordered according to chip registers.
> > > + * Keep it u8 only to avoid padding issues.
> > > + */
> > > +struct bd70528_rtc_day {
> > > +	u8 sec;
> > > +	u8 min;
> > > +	u8 hour;
> > > +};
> > > +
> > > +struct bd70528_rtc_data {
> > > +	struct bd70528_rtc_day time;
> > > +	u8 week;
> > > +	u8 day;
> > > +	u8 month;
> > > +	u8 year;
> > > +};
> > > +
> > > +struct bd70528_rtc_wake {
> > > +	struct bd70528_rtc_day time;
> > > +	u8 ctrl;
> > > +};
> > > +
> > > +struct bd70528_rtc_alm {
> > > +	struct bd70528_rtc_data data;
> > > +	u8 alm_mask;
> > > +	u8 alm_repeat;
> > > +};
> >
> > At least some of the above are directly associated with chip registers.
> > I don't think this will work for all architectures without explicit packed
> > attribute.
>
> Allright. I was thinking of that but thought that most of the
> architectures using this PMIC would handle alignments fine if I used
> only u8 members. I did consider using __attribute__((packed)) - but I'm
> not sure if we hit into troubles with that too. I guess some people
> would like to compile kernel with other compiler(s) but gcc - although
> I'm not sure if this should be taken into account. I'll try doing some
> study on this - unless someone replies to this and just tells how this
> should be done. (I am pretty sure I can find the answer from mail
> archives though). I'll try adding some packing hint for compiler at v3.

Use __packed ?

> > > +		if ((!enable) == (!(*old_state & BD70528_WAKE_STATE_BIT)))
> > > +			return 0;
> >
> > I think
> > 		if (enable == !!(*old_state & BD70528_WAKE_STATE_BIT))
> > would be much better readable. Even if not, there are way too many ()
> > in the above conditional.
>
> Allright. I'll fix this
>   
> > > +	if (alm.alm_mask & BD70528_MASK_ALM_EN)
> > > +		a->enabled = 0;
> > > +	else
> > > +		a->enabled = 1;
> > > +
> > Without conditional:
> > 	a->enabled = !(alm.alm_mask & BD70528_MASK_ALM_EN);
>
> Right. Much nicer, thanks! I'll change this.
>
> > > +static int bd70528_set_time(struct device *dev, struct rtc_time *t)
> > > +{
> > > +	int ret, old_states;
> > > +	struct bd70528_rtc_data rtc_data;
> > > +	struct bd70528_rtc *r = dev_get_drvdata(dev);
> > > +	struct bd70528 *bd70528 = r->mfd;
> > > +
> > > +	ret = bd70528_disable_rtc_based_timers(r, &old_states);
> > > +
> >
> > AFAICS the disable/enable functions are only called once. Since they
> > also apply set / clear a mutex, I find that a bit confusing. I think
> > it would be better to fold the code into this function. If anything,
> > I could imagine something like
> >
> > 	mutex_lock();
> > 	ret = bd70528_set_time_locked();
> > 	mutex_unlock()
> >
> > to simplify error handling.
>
> Yep. Makes sense. I'll tidy this.
>
> > > +	ret = regmap_bulk_read(bd70528->chip.regmap,
> > > +			       BD70528_REG_RTC_START, &rtc_data,
> > > +			       sizeof(rtc_data));
> > > +
> > > +	tm2rtc(t, &rtc_data);
> > > +
> > > +	ret = regmap_bulk_write(bd70528->chip.regmap,
> > > +				BD70528_REG_RTC_START, &rtc_data,
> > > +				sizeof(rtc_data));
> > > +
> > > +	ret = bd70528_re_enable_rtc_based_timers(r, old_states);
> > > +
> >
> > Kind of off that all the error returns are ignored here.
>
> And I'll fix this too.
>
> Br,
> 	Matti Vaittinen