[RFC PATCH 08/12] ARM: msm: use remapped PPI interrupts for local timer

[Russell King - ARM Linux]

On Tue, Apr 26, 2011 at 10:13:52AM -0700, Stephen Boyd wrote:
> Why do we need to call local_timer_setup() on each CPU up though? It
> would be nice to be able to just add local timers for all possible CPUs
> at boot time and then have the clockevents core take care of enabling
> and disabling the events as appropriate without ARM code forcing the
> events to be UNUSED and then re-adding the events back on CPU up. I'm
> probably missing something really obvious here.

Firstly, because you can't access the local timer registers from non-
local CPUs.  Secondly, when you offline a CPU, generic code unregisters
the local timer, so whenever you online a CPU you have to add its local
timer clockevent back again.

Thirdly, you may have a system where the local timer gets powered down
when a CPU is offlined, and so it would need reinitialization when you
online it again.