[PATCH 3/5] ARM: twd: Add context save restore support

-----Original Message-----
From: Russell King - ARM Linux [mailto:linux at arm.linux.org.uk]
Sent: Tuesday, January 25, 2011 5:00 PM
To: Colin Cross
Cc: Santosh Shilimkar; catalin.marinas at arm.com;
linus.ml.walleij at gmail.com; linux-omap at vger.kernel.org; linux-arm-
kernel at lists.infradead.org
Subject: Re: [PATCH 3/5] ARM: twd: Add context save restore support

On Mon, Jan 24, 2011 at 11:39:13PM -0800, Colin Cross wrote:

quoted

This doesn't work for oneshot timers if the TWD_TIMER_CONTROL

register

quoted

gets reset by cpu idle between twd_set_mode and

twd_set_next_event.

quoted

Shadowing ctrl in a percpu variable and rewriting it during every

call

quoted

to twd_set_next_event does work, but that's not much different,

and a

quoted

little less efficient, than just saving and restoring the control

and

quoted

load registers in idle.  It does have the advantage that platforms
don't need any extra calls.

BTW, do you think the patch is, nevertheless, an improvement and
something
we should do?  If so, please can I have your ack for it?

As I was suspecting the one shot mode wouldn't work it. Collin
just confirmed it.
To make it fully work it needs control register save restore.
And that can be managed within TWD library so that every platform
doesn't have to bother of calling it from their idle code.

Do you prefer that as a separate patch or I can post a new version
in which can add your fix + per cpu control register shadowing ?

Regards,
Santosh