On 20/08/2017 at 23:10:16 +0200, Andreas F?rber wrote:

quoted

Is RTD_RTCDATE_HIGH latched when RTD_RTCDATE_LOW is read?

I do not have an answer to that.

quoted

If this is not
the case, you probably want to handle a possible update between both
readl_relaxed.

Are you proposing to disable the RTC while reading the registers, or
something related to my choice of _relaxed? (it follows an explanation
by Marc Zyngier on the irq mux series) Inconsistencies might not be
limited to the date.

A simple way to be sure would be to read RTD_RTCSEC first, then the
other registers and check RTD_RTCSEC didn't change. This will ensure the
other registers have not be updated in the meantime (unless it takes
one minute but I doubt this is the case). if RTD_RTCSEC changed, then
you can start over.

quoted

quoted

+	t = mktime64(data->base_year, 1, 1, 0, 0, 0);
+	t += day * 24 * 60 * 60;
+	rtc_time64_to_tm(t, tm);

BTW is there any more efficient way to get from year+days to
day/month/year without going via seconds?

Completely untested:

for (y = data->base_year; (day - (365 + is_leap_year(y))) > 0; y++)
	day -= (365 + is_leap_year(y));

for (m = 0; (day - rtc_month_days(m, y)) > 0; m++)
	day -= rtc_month_days(m, y);

quoted

quoted

+
+	rtd119x_rtc_set_enabled(dev, true);
+

This is certainly not what you want. The RTC device is usually not
opened so enabling the RTC when open and disabling it when closed will
not work on most systems. This is probably true for the clock too. i.e
what you do here should be done in probe.

I did test the probe path to work, but I can change it again. The
downstream code had it in probe, but looking at rtc_class_ops I saw
those hooks and thought they'd serve a purpose - what are they for then?
(Any chance you can improve the documentation comments to avoid such
misunderstandings? :))

They are (were) used only when the rtc character device (/dev/rtcx) is
opened/released but the cdev interface is one of many interfaces to the
RTC sod it doesn't make sense to do something only in that case
(especially requesting IRQs).

To solve your concern, this is what I'm going to apply after fixing the
two remaining uses of .release:

http://patchwork.ozlabs.org/patch/804707/


-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com