[PATCH v2 00/15] Make SMP timers standalone

[Linus Walleij]

On Thu, Jan 5, 2012 at 2:17 AM, David Brown <davidb at codeaurora.org> wrote:
> On Wed, Jan 04, 2012 at 05:39:16PM +0000, Marc Zyngier wrote:
>> I do. But on some non-SMP platforms, the local timer and the global
>> timer can actually be the same (MSM is one example of this, and the UP
>> version of the Cortex A15 is another).
>
> On SMP MSM, we use the CPU0 local timer as the global timer.  They are
> the same on non-SMP as well,

Does this mean your CPU0 local timer is always on, always clocked?
And do you use ARMs SMP TWD IP block for that?

> I guess, but as Russell says, I'm not
> sure what the concept of a local timer would mean on non-SMP.

I think this looks like one big misunderstanding. I understood it as
the SMP TWD block is synthesized also on UP silicon, i.e. same
hardware, and so it will need to use the driver from
arch/arm/kernel/smp_twd.c, however there is nothing local
about that apart from being in close locality of the CPU.

Let us talk about the SMP TWD timer block for A8/A9 systems if
that is what it's all about (is it? maybe I'm confused too...)
and architectured timers for A15.

Linus Walleij