Re: [PATCH] rtc: add rtc_systohc for ntp use

From: Andrew Morton
Date: Mon Feb 02 2009 - 17:28:41 EST


On Mon, 26 Jan 2009 17:04:22 -0800
Ed Swierk <eswierk@xxxxxxxxxxxxxxxxxx> wrote:

> Following up to Alessandro's RFC of 10 Nov 2008, this patch implements
> rtc_systohc() to update the configured rtc device (cmos, i2c, etc.) from
> the ntp-synchronized system clock. It changes the ntp update code to
> call rtc_systohc() rather than update_persistent_clock() which (at least
> on x86) always updates the cmos rtc.
>
> No attempt is made to compensate for the 500-ms delay imposed when
> setting a cmos rtc chip. If you actually have a cmos rtc you can stick
> with the existing code, but at some point it would be nice to unify
> these.

I don't get this. Do we not currently update the cmos clock in
response to NTP controls? Does the patch now alter this policy, by now
updating the RTC?

IOW: what effect does this patch actually have upon the kernel?


Please cc Roman on NTP changes. Roman, please consider sending in a
MAINTAINERS patch for this.


Please use scripts/checkpatch.pl.

Please fix the checkpatch warnings which this patch emits.

When fixing the extern-declaration-in-C warning, please consider
dropping the ifdefs around the rtc_systohc() declaration in the header
file. They're not really needed.

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