OMAP3+: SR: ensure pm-runtime callbacks can be invoked with IRQ disabled

SmartReflex should be disabled while entering low power mode due to
a) SmartReflex values are not defined for retention voltageFurther
b) with SmartReflex enabled, if CPU enters lower c-states, FSM will try to bump the voltage to current OPP's voltage for which it has entered c-state; hence SmartReflex needs to be disabled for MPU, CORE and IVA voltage domains in idle path before enabling auto retention voltage achievement on the device.

However, since the current pm_runtime setup for SmartReflex devices are setup to allow callbacks to be invoked with interrupts enabled, calling SmartReflex enable/disable from other contexts such as idle paths where preemption is disabled causes warnings such as the following indicating of a potential race.

[   82.023895] [<c04d079c>] (__irq_svc+0x3c/0x120) from [<c04d0484>] (_raw_spin_unlock_irq+0x28/0x2c)
[   82.023895] [<c04d0484>] (_raw_spin_unlock_irq+0x28/0x2c) from [<c0323234>] (rpm_callback+0x4c/0x68)
[   82.023956] [<c0323234>] (rpm_callback+0x4c/0x68) from [<c0323f7c>] (rpm_resume+0x338/0x53c)
[   82.023956] [<c0323f7c>] (rpm_resume+0x338/0x53c) from [<c03243f4>] (__pm_runtime_resume+0x48/0x60)
[   82.023986] [<c03243f4>] (__pm_runtime_resume+0x48/0x60) from [<c008aee0>] (sr_enable+0xa8/0x19c)
[   82.023986] [<c008aee0>] (sr_enable+0xa8/0x19c) from [<c008b2fc>] (omap_sr_enable+0x50/0x90)
[   82.024017] [<c008b2fc>] (omap_sr_enable+0x50/0x90) from [<c00888c0>] (omap4_enter_sleep+0x138/0x168)

Instead, we use pm_runtime_irq_safe to tell the PM core that callbacks can be invoked in interrupt disabled contexts.

---
 arch/arm/mach-omap2/smartreflex.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

index f8c6305..444c5b2 100644
@@ -862,6 +862,7 @@ static int __init omap_sr_probe(struct platform_device *pdev)
 	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 
 	pm_runtime_enable(&pdev->dev);
+	pm_runtime_irq_safe(&pdev->dev);
 
 	sr_info->pdev = pdev;
 	sr_info->srid = pdev->id;

1.7.1

Tony,

This should go in for v3.1 also.

I made some minor changelog edits and put in my for_3.0/pm-fixes-3 branch.

Kevin