linux-kernel - Re: RTC seems broken on 2.6.38-rc1 for RTCs lacking alarms.

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Message-ID: <1295558196.2998.85.camel@work-vm>
Date:	Thu, 20 Jan 2011 13:16:36 -0800
From:	John Stultz <john.stultz@...aro.org>
To:	David Daney <ddaney@...iumnetworks.com>,
	Andreas Schwab <schwab@...ux-m68k.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: RTC seems broken on 2.6.38-rc1 for RTCs lacking alarms.

On Thu, 2011-01-20 at 12:51 -0800, David Daney wrote:
> open("/dev/rtc0", O_RDONLY|O_LARGEFILE) = 3
> ioctl(3, PRESTO_GETMOUNT or RTC_UIE_ON, 0) = 0
> _newselect(4, [3], NULL, NULL, {5, 0})  = 0 (Timeout)
> write(2, "select() to /dev/rtc0 to wait for"..., 55select() to /dev/rtc0 
> to wait for clock tick timed out
> ) = 55
> ioctl(3, PRESTO_SETPID or RTC_UIE_OFF, 0) = 0
> close(3)                                = 0
> exit_group(1)                           = ?
> 
> 
> The hwclock program is asking to put the clock in UIE mode and then
> does a select() on it.  Since the alarm doesn't work, the select times out.
> 
> Previously the ioctl(RTC_UIE_ON) would return EINVAL:

Ah. Good diagnosis! Let me try to get a patch for you and Andreas to
test.

thanks
-john


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