Re: [PATCH] rtc: ds1307: Fix relying on reset value for weekday

From: Keerthy
Date: Wed Jun 15 2016 - 00:16:15 EST




On Tuesday 14 June 2016 08:09 PM, Alexandre Belloni wrote:
On 07/06/2016 at 14:59:05 +0530, Keerthy wrote :
Hi Alexandre,

On Wednesday 01 June 2016 06:06 PM, Keerthy wrote:


On Wednesday 01 June 2016 05:48 PM, Alexandre Belloni wrote:
Hi,

On 01/06/2016 at 16:19:07 +0530, Keerthy wrote :
The reset value of weekday is 0x1. This is wrong since
the reset values of the day/month/year make up to Jan 1 2001.
When computed weekday comes out to be Monday. On a scale
of 1-7(Sunday - Saturday) it should be 0x2. So we should not
be relying on the reset value.


Hum, what are the chances that the reset value is actually the correct
date/time?
Won't that be corrected after the first call to set_time? Until then,
the date is not correct so, do we care anyway?

Yes if an alarm is programmed without set_time.

ex: rtcwake -d /dev/rtc0 -s 5

Even the basic rtctest under tools/testing/selftests/timers/rtctest.c fails
as the wday is wrong and no alarm fires.

Instead of relying on some one to call set_time before programming alarm
its better to fix the wday to reflect the current day right?



Maybe I'm missing something here.

Let me know if you feel this is a valid fix.


Well, this is probably a valid fix and I'll take it as is if I don't
find the time to make something more generic.

Okay Thanks.