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

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Date:	Wed, 15 Jun 2016 09:44:41 +0530
From:	Keerthy <a0393675@...com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Keerthy <j-keerthy@...com>, <a.zummo@...ertech.it>, <nm@...com>,
	<rtc-linux@...glegroups.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] rtc: ds1307: Fix relying on reset value for weekday



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.

>