linux-kernel - Re: [PATCH v2] RTC/PCF85063: fix reading/setting time/date

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Message-ID: <20160223230437.GC10681@piout.net>
Date:	Wed, 24 Feb 2016 00:04:37 +0100
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Juergen Borleis <jbe@...gutronix.de>
Cc:	rtc-linux@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	linux-kernel@...r.kernel.org, kernel@...gutronix.de,
	jbe@...gutronix.de
Subject: Re: [PATCH v2] RTC/PCF85063: fix reading/setting time/date

On 09/02/2016 at 11:57:24 +0100, Juergen Borleis wrote :
> The PCF85063 RTC needs special treatment while setting or reading the
> time/date:
> 
>  - when reading the 7 time/date registers they are blocked from updating by
>    the 'one second' pulse internally. So reading all time/date registers
>    should happen in one turn to ensure reading is an atomic operation
> 
>  - to let setting the time/date be an atomic operation as well, the clock
>    dividers must be kept in reset state to avoid a 'one second' pulse during
>    writing the 7 time/date registers
> 
> Changes from v1:
> 
>  - using high level I2C access functions instead of the low level i2c_transfer()
>    to simplify the code
> 

All applied, thanks!

However, I found two interesting things in that driver. I'll send a
patch shortly, removing the useless century handling.
Also, I'm quite unsure about the year range handling. I have a patch but
I'm not sure about the RTC behaviour when the year goes from 99 to 00.
Can you check that works properly?

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