linux-kernel - Re: [RFC+PATCH] RTC calibration

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Message-ID: <46E6A737.6080805@anagramm.de>
Date:	Tue, 11 Sep 2007 16:33:27 +0200
From:	Clemens Koller <clemens.koller@...gramm.de>
To:	Dag-Erling Smørgrav <des@...pro.no>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [RFC+PATCH] RTC calibration

Dag-Erling Smørgrav schrieb:
 > The STMicroelectronics M41T11 is an RTC chip which is similar in most
 > ways to the Dallas/Maxim DS1307 or DS1337, except that it supports
 > software calibration:
 >
 > http://www.st.com/stonline/books/pdf/docs/6103.pdf
 >
 > I want to use this calibration feature [...]
 > [...]
 > In order to access this from userland, I've added two ioctls,
 > (RTC_SPEED_UP and RTC_SPEED_DOWN) with corresponding functions in
 > drivers/rtc/interface.c (rtc_speed_up() and rtc_speed_down()) and
 > corresponding slots in rtc_class_ops (speed_up and speed_down).

It looks odd to me to do only differential up and down adjustments.
I would prefer read_calibration_register and write_calibration_register
access and let the userspace decide how much it wants to
increment/decrement the register.

Or - do you adjust your date also after you changed your battery
with +1567days,7h,34m,12sec instead of telling it's 11th Sept. 2007, 4:33pm ?

Regards,

Clemens Koller
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