linux-kernel - Re: [patch 2.6.25-rc2-git 2/2] atmel

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Date:	Tue, 26 Feb 2008 01:25:33 -0800
From:	David Brownell <david-b@...bell.net>
To:	Haavard Skinnemoen <hskinnemoen@...el.com>
Cc:	nicolas.ferre@....atmel.com, linux@...im.org.za,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [patch 2.6.25-rc2-git 2/2] atmel_tc clocksource/clockevent code

On Tuesday 26 February 2008, Haavard Skinnemoen wrote:
> > Another way to address that rm9200 issue would be to just rate
> > the TC clockevent source lower than the one based on the system
> > timer, so it's set up but never enabled ... and remember "t2_clk",
> > calling clk_enable() only when that clockevent device is active.
> > 
> > That would address one half of the suspend/resume equation too,
> > ensuring that clock is disabled during suspend...
> 
> Yes, we could probably do that. Which means we can just remove all the
> ifdeffery?

There'd still be the #ifdef for CONFIG_GENERIC_CLOCKEVENTS,
unless all the platforms get updated to support that.  Right
now it's a "patches available but not merged" situation.


> > The other half being:  how to clk_disable(t0_clk) during system
> > suspend?  (And t1_clk on some systems.)  There's currently no
> > clocksource.set_mode() call; evidently there's an assumption that
> > such counters cost no power, so they can always be left running.
> 
> Yes...that would be a clocksource core issue I guess. Better leave that
> for later...

My thoughts exactly.  ;)

Plus a bit of puzzlement why that didn't trigger at least a
warning during AT91 suspend testing.  There used to be warnings
there about clocks which were wrongly left enabled...

- Dave
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