[v2,09/18] ARM: OMAP4+: PM: Restore CPU power state to ON with clockdomain force wakeup method

Commit Message

Santosh Shilimkar March 25, 2013, 10:05 a.m. UTC

While waking up CPU from off state using clock domain force wakeup, restore
the CPU power state to ON state before putting CPU clock domain under
hardware control. Otherwise CPU wakeup might fail. The change is recommended
for all OMAP4+ devices though the PRCM weakness was observed on OMAP5
devices first.

So update the code accordingly.

Acked-by: Nishanth Menon <[e-mail]>
Signed-off-by: Santosh Shilimkar <[e-mail]>
---
 arch/arm/mach-omap2/cpuidle44xx.c |    1 +
 arch/arm/mach-omap2/omap-smp.c    |   12 ++++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

Comments

Kevin Hilman April 3, 2013, 8:54 p.m. UTC | #1

Santosh Shilimkar <[e-mail]> writes:

> While waking up CPU from off state using clock domain force wakeup, restore
> the CPU power state to ON state before putting CPU clock domain under
> hardware control. Otherwise CPU wakeup might fail. The change is recommended
> for all OMAP4+ devices though the PRCM weakness was observed on OMAP5
> devices first.

Sounds reasonable, but can you describe the "weakness" a little more?

IOW, what exactly happens if this is not done?  It sounds like the CPU
might immediately go back to retention, but how does that happen unless
it does a WFI?

Also, this sounds like a fix to me, and should probably be broken out
accordingly.

Kevin

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Patch

diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c
index 944e64a..9de47a7 100644
--- a/arch/arm/mach-omap2/cpuidle44xx.c
+++ b/arch/arm/mach-omap2/cpuidle44xx.c
@@ -131,6 +131,7 @@  static int omap4_enter_idle_coupled(struct cpuidle_device *dev,
 	/* Wakeup CPU1 only if it is not offlined */
 	if (dev->cpu == 0 && cpumask_test_cpu(1, cpu_online_mask)) {
 		clkdm_wakeup(cpu_clkdm[1]);
+		omap_set_pwrdm_state(cpu_pd[1], PWRDM_POWER_ON);
 		clkdm_allow_idle(cpu_clkdm[1]);
 	}
 
diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
index 0cbb677..e4441cc 100644
--- a/arch/arm/mach-omap2/omap-smp.c
+++ b/arch/arm/mach-omap2/omap-smp.c
@@ -83,6 +83,7 @@  static int __cpuinit omap4_boot_secondary(unsigned int cpu, struct task_struct *
 {
 	static struct clockdomain *cpu1_clkdm;
 	static bool booted;
+	static struct powerdomain *cpu1_pwrdm;
 	void __iomem *base = omap_get_wakeupgen_base();
 
 	/*
@@ -102,8 +103,10 @@  static int __cpuinit omap4_boot_secondary(unsigned int cpu, struct task_struct *
 	else
 		__raw_writel(0x20, base + OMAP_AUX_CORE_BOOT_0);
 
-	if (!cpu1_clkdm)
+	if (!cpu1_clkdm && !cpu1_pwrdm) {
 		cpu1_clkdm = clkdm_lookup("mpu1_clkdm");
+		cpu1_pwrdm = pwrdm_lookup("cpu1_pwrdm");
+	}
 
 	/*
 	 * The SGI(Software Generated Interrupts) are not wakeup capable
@@ -116,7 +119,7 @@  static int __cpuinit omap4_boot_secondary(unsigned int cpu, struct task_struct *
 	 * Section :
 	 *	4.3.4.2 Power States of CPU0 and CPU1
 	 */
-	if (booted) {
+	if (booted && cpu1_pwrdm && cpu1_clkdm) {
 		/*
 		 * GIC distributor control register has changed between
 		 * CortexA9 r1pX and r2pX. The Control Register secure
@@ -137,7 +140,12 @@  static int __cpuinit omap4_boot_secondary(unsigned int cpu, struct task_struct *
 			gic_dist_disable();
 		}
 
+		/*
+		 * Ensure that CPU power state is set to ON to avoid CPU
+		 * powerdomain transition on wfi
+		 */
 		clkdm_wakeup(cpu1_clkdm);
+		omap_set_pwrdm_state(cpu1_pwrdm, PWRDM_POWER_ON);
 		clkdm_allow_idle(cpu1_clkdm);
 
 		if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD)) {