[PATCH 02/12] arm: omap3: Only sleep during cpu_idle if I/O wake-ups work

Mark A. Greer
2012-04-11T19:48:11Z

From: "Mark A. Greer" <mgreer@animalcreek.com>

Currently in the OMAP3 code, cpu_idle() calls pm_idle(),
which is a function pointer set to omap3_pm_idle()).
omap3_pm_idle() calls omap_sram_idle() which eventually
causes a 'wfi' instruction to be executed effectively
putting the system to sleep. It is assumed that an
I/O wake-up event will occur to wake the system up again.
This doesn't work on systems that don't support I/O wake-ups
(indicated by omap3_has_io_wakeup() returning false).

Leaving pm_idle() pointing to default_idle() won't work
either because the cpu_<processor>_do_idle() routine which
is eventually called may also execute a 'wfi' instruction
(e.g., cpu_v7_do_idle()).

To handle this, leave pm_idle() pointing to omap3_pm_idle()
but add a check in omap3_pm_idle() so it avoids calling
omap_sram_idle() when I/O wake-ups aren't supported.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
---
arch/arm/mach-omap2/pm34xx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index ec92676..b7bbcee 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -397,7 +397,7 @@ static void omap3_pm_idle(void)
{
local_fiq_disable();

- if (omap_irq_pending())
+ if (omap_irq_pending() || !omap3_has_io_wakeup())
goto out;

trace_power_start(POWER_CSTATE, 1, smp_processor_id());
--
1.7.9.4