linux-kernel - Re: [RFC][PATCH] alarmtimers: Handle late rtc module loading

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Message-ID: <alpine.SOC.1.00.1106202308050.29718@math.ut.ee>
Date:	Mon, 20 Jun 2011 23:09:56 +0300 (EEST)
From:	Meelis Roos <mroos@...ux.ee>
To:	John Stultz <john.stultz@...aro.org>
cc:	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC][PATCH] alarmtimers: Handle late rtc module loading

> > One the PC, I get the following about RTC in dmesg:
> > 
> > [    0.319145] drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
> > [    3.614132] rtc_cmos 00:03: RTC can wake from S4
> > [    3.614480] rtc_cmos 00:03: rtc core: registered rtc_cmos as rtc0
> > [    3.614582] rtc0: alarms up to one year, y3k, 114 bytes nvram
> 
> I'll double check, but I suspect that "unable to open rtc device"
> message isn't new. The issue is that the rtc_cmos driver is built as a
> module, and the hctosys functionality is running before the module is
> loaded.

Yes. But I consider this a configuration error - to load modular rtc 
driver and expect boottime clock setting from it works. It was by 
mistake - the boottime options came later in time. Changed it to 
statically compiled in PC CMOS RTC and it works fine.

> Hmmm. This maybe points to the need for some sort of callback system for
> when RTC devices are registered. Since most existing code is just hoping
> its available by late_init.

Is it really necessary?

-- 
Meelis Roos (mroos@...ux.ee)
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