Re: [PATCH v2 2/4] rtc: Add support for the MediaTek MT2712 RTC

Ran Bi
2019-08-22T12:34:27Z

Hi,

> > +
> > +#define MTK_RTC_DEV KBUILD_MODNAME
>
> You probably shouldn't do that and have a static string for the driver
> name. I probably doesn't matter much though because DT is used to probe
> the driver.
>

Will change it at next patch.

> > +/* we map HW YEAR 0 to 2000 because 2000 is the leap year */
> > +#define MT2712_MIN_YEAR 2000
> > +#define MT2712_BASE_YEAR 1900
> > +#define MT2712_MIN_YEAR_OFFSET (MT2712_MIN_YEAR - MT2712_BASE_YEAR)
> > +#define MT2712_MAX_YEAR_OFFSET (MT2712_MIN_YEAR_OFFSET + 127)
> > +
>
> All those defines are unecessary, see below.
>

Will change it at next patch.

> > +struct mt2712_rtc {
> > + struct device *dev;
>
> Looking at the code closely, it seems this is only used for debug and
> error messages. Maybe you could use rtc_dev->dev instead.
>

Will change it at next patch.

> > + mutex_lock(&rtc->rtc_dev->ops_lock);
> > +
> > + irqsta = mt2712_readl(rtc, MT2712_IRQ_STA);
>
> Do you have to lock that read? Is the register cleared on read?
>

Yes, this register is read clear register.

> > + do {
> > + __mt2712_rtc_read_time(rtc, tm, &sec);
> > + } while (sec < tm->tm_sec); /* SEC has carried */
>
> Shouldn't that be while (tm->tm_sec < sec)?
>

In __mt2712_rtc_read_time function, we read tm->tm_sec before read sec.
Sometimes we can meet situation like "tm->tm_sec == 59" and "sec == 0".
It means that TC_SEC has carried and we need to reload the tm struct. I
suppose it was correct that using "while (sec < tm->tm_sec)"

> > +
> > + /* HW register use 7 bits to store year data, minus
> > + * MT2712_MIN_YEAR_OFFSET brfore write year data to register, and plus
> > + * MT2712_MIN_YEAR_OFFSET back after read year from register
> > + */
> > + tm->tm_year += MT2712_MIN_YEAR_OFFSET;
>
> Simply add 100 in __mt2712_rtc_read_time
>

Will change it at next patch.

> > +
> > + /* HW register start mon from one, but tm_mon start from zero. */
> > + tm->tm_mon--;
> > +
>
> You can also do that in __mt2712_rtc_read_time.
>

Will change it at next patch.

> > + if (rtc_valid_tm(tm)) {
>
> This check is unnecessary, the validity is always checked by the core.
>

Will remove this at next patch.

> > + if (tm->tm_year > MT2712_MAX_YEAR_OFFSET) {
> > + dev_dbg(rtc->dev, "Set year %d out of range. (%d - %d)\n",
> > + 1900 + tm->tm_year, 1900 + MT2712_MIN_YEAR_OFFSET,
> > + 1900 + MT2712_MAX_YEAR_OFFSET);
> > + return -EINVAL;
> > + }
>
> This check is unnecessary, see below.
>

Will change it at next patch.

> > +
> > + tm->tm_year -= MT2712_MIN_YEAR_OFFSET;
> > + tm->tm_mon++;
>
> You should probably avoid modifying tm, move the substraction and
> addition in the mt2712_writel calls.
>

Will change it at next patch.

> > + if (tm->tm_year > MT2712_MAX_YEAR_OFFSET) {
> > + dev_dbg(rtc->dev, "Set year %d out of range. (%d - %d)\n",
> > + 1900 + tm->tm_year, 1900 + MT2712_MIN_YEAR_OFFSET,
> > + 1900 + MT2712_MAX_YEAR_OFFSET);
> > + return -EINVAL;
> > + }
> > +
>
> Unnecessary check.
>

Will change it at next patch.

> > + p1 = mt2712_readl(rtc, MT2712_POWERKEY1);
> > + p2 = mt2712_readl(rtc, MT2712_POWERKEY2);
> > + if (p1 != MT2712_POWERKEY1_KEY || p2 != MT2712_POWERKEY2_KEY)
> > + dev_dbg(rtc->dev, "powerkey not set (lost power)\n");
> > +
>
> This info is valuable, you should check that when reading the time and
> return -EINVAL if power was lost.
>

Will change it at next patch.

>
> > + /* RTC need POWERKEY1/2 match, then goto normal work mode */
> > + mt2712_writel(rtc, MT2712_POWERKEY1, MT2712_POWERKEY1_KEY);
> > + mt2712_writel(rtc, MT2712_POWERKEY2, MT2712_POWERKEY2_KEY);
>
> This should be written when setting the time after power was lost.
>

I suppose we can move this into mt2712_rtc_read_time function's "if
(p1 != MT2712_POWERKEY1_KEY || p2 != MT2712_POWERKEY2_KEY)" condition
which will be added at next patch. We need additional flag to mark this
condition or another if condition in mt2712_rtc_set_time fucntion if we
put these code in mt2712_rtc_set_time function.

> > +static const struct rtc_class_ops mt2712_rtc_ops = {
> > + .read_time = mt2712_rtc_read_time,
> > + .set_time = mt2712_rtc_set_time,
> > + .read_alarm = mt2712_rtc_read_alarm,
> > + .set_alarm = mt2712_rtc_set_alarm,
>
> For proper operations, you should also provide the .alarm_irq_enable
> callback.
>

Will change it at next patch.

> > + rtc->rtc_dev->ops = &mt2712_rtc_ops;
>
> If you set the range properly here using rtc_dev->range_min and
> rtc_dev->range_max, then the core will be able to do range checking and
> will also take care of the year offset/windowing calculations instead of
> having to hardcode that in the driver.
>

Will change it at next patch.

Best Regards,
Ran