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From: john stultz <johnstul@us.ibm.com>
To: Paul Mackerras <paulus@samba.org>
Cc: Realtime Kernel <linux-rt-users@vger.kernel.org>,
	Daniel Walker <dwalker@mvista.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 2/5] Implement generic time of day clocksource for powerpc machines.
Date: Thu, 20 Sep 2007 09:35:10 -0700	[thread overview]
Message-ID: <1190306110.14264.7.camel@localhost> (raw)
In-Reply-To: <18161.50240.599267.768383@cargo.ozlabs.ibm.com>

On Thu, 2007-09-20 at 10:52 +1000, Paul Mackerras wrote:
> Daniel Walker writes:
> 
> > If you switch to the rtc do the shift and mult need to change?
> 
> You can't switch; any given CPU chip will have either the RTC or the
> timebase but not both.

I think what Daniel is pointing out is that the clocksource read
function isn't the place for the __USE_RTC() conditional. 

It would likely be better instead of the timebase clocksource managing
multiple type of hardware (timebase and RTC), to have a separate simple
RTC clocksource, and then conditionally register one or the other at
init time.

thanks
-john

WARNING: multiple messages have this Message-ID (diff)
From: john stultz <johnstul@us.ibm.com>
To: Paul Mackerras <paulus@samba.org>
Cc: Daniel Walker <dwalker@mvista.com>,
	Tony Breeds <tony@bakeyournoodle.com>,
	linuxppc-dev@ozlabs.org, Thomas Gleixner <tglx@linutronix.de>,
	Realtime Kernel <linux-rt-users@vger.kernel.org>
Subject: Re: [PATCH 2/5] Implement generic time of day clocksource for powerpc machines.
Date: Thu, 20 Sep 2007 09:35:10 -0700	[thread overview]
Message-ID: <1190306110.14264.7.camel@localhost> (raw)
In-Reply-To: <18161.50240.599267.768383@cargo.ozlabs.ibm.com>

On Thu, 2007-09-20 at 10:52 +1000, Paul Mackerras wrote:
> Daniel Walker writes:
> 
> > If you switch to the rtc do the shift and mult need to change?
> 
> You can't switch; any given CPU chip will have either the RTC or the
> timebase but not both.

I think what Daniel is pointing out is that the clocksource read
function isn't the place for the __USE_RTC() conditional. 

It would likely be better instead of the timebase clocksource managing
multiple type of hardware (timebase and RTC), to have a separate simple
RTC clocksource, and then conditionally register one or the other at
init time.

thanks
-john

  parent reply	other threads:[~2007-09-20 17:43 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-19  6:49 [PATCH 1/5] Implement {read,update}_persistent_clock Tony Breeds
2007-09-19  6:49 ` [PATCH 2/5] Implement generic time of day clocksource for powerpc machines Tony Breeds
2007-09-19 15:43   ` Daniel Walker
2007-09-19 15:43     ` Daniel Walker
2007-09-20  0:52     ` Paul Mackerras
2007-09-20  0:52       ` Paul Mackerras
2007-09-20  1:35       ` Daniel Walker
2007-09-20  1:35         ` Daniel Walker
2007-09-20  1:46         ` Paul Mackerras
2007-09-20  1:46           ` Paul Mackerras
2007-09-20  1:54           ` Daniel Walker
2007-09-20  1:54             ` Daniel Walker
2007-09-20  3:29             ` David Gibson
2007-09-20  3:29               ` David Gibson
2007-09-20  3:38               ` Daniel Walker
2007-09-20  3:38                 ` Daniel Walker
2007-09-20 16:35       ` john stultz [this message]
2007-09-20 16:35         ` john stultz
2007-09-20 23:46         ` Tony Breeds
2007-09-20 23:46           ` Tony Breeds
2007-09-19  6:49 ` [PATCH 3/5] Implement clockevents driver for powerpc Tony Breeds
2007-09-19  6:49 ` [PATCH 4/5] Include hrtimer.h in tick.h Tony Breeds
2007-09-19  6:49 ` [PATCH 5/5] Enable tickless idle and high res timers for powerpc Tony Breeds
2007-09-19  6:53 ` [PATCH 1/5] Implement {read,update}_persistent_clock Tony Breeds

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