Groups > linux.kernel > #1421976

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

From	Alexandre Belloni <alexandre.belloni@free-electrons.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] rtc: ds1307: Fix relying on reset value for weekday
Date	2016-06-14 16:50 +0200
Message-ID	<rJXPd-66e-49@gated-at.bofh.it> (permalink)
References	<rFc2u-7m8-23@gated-at.bofh.it> <rFdhT-8iE-17@gated-at.bofh.it> <rFdBg-8pl-19@gated-at.bofh.it> <rHlEm-Wz-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

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.

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

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH] rtc: ds1307: Fix relying on reset value for weekday Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2016-06-14 16:50 +0200
  Re: [PATCH] rtc: ds1307: Fix relying on reset value for weekday Keerthy <a0393675@ti.com> - 2016-06-15 06:20 +0200

csiph-web