tree 1e45cd7687b4b0eb9eca5339d92c79abae5db0b5
parent 94eab0bb206443dd7480349804f64e2bba8dc6e1
author Paul Mundt <lethal@linux-sh.org> 1255681258 +0900
committer Paul Mundt <lethal@linux-sh.org> 1255681258 +0900

sh: Idle loop chainsawing for SMP-based light sleep.

This does a bit of chainsawing of the idle loop code to get light sleep
working on SMP. Previously this was forcing secondary CPUs in to sleep
mode with them not coming back if they didn't have their own local
timers. Given that we use clockevents broadcasting by default, the CPU
managing the clockevents can't have IRQs disabled before entering its
sleep state.

This unfortunately leaves us with the age-old need_resched() race in
between local_irq_enable() and cpu_sleep(), but at present this is
unavoidable. After some more experimentation it may be possible to layer
on SR.BL bit manipulation over top of this scheme to inhibit the race
condition, but given the current potential for missing wakeups, this is
left as a future exercise.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>