ARM: OMAP4+: PM: Restore CPU power state to ON with clockdomain force wakeup method

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.

As a result of weakness, lock-up is observed inside the hardware state
machine of local CPU PRCM and results are UN-predictable as per designers.
In software testing, we have seen hard-locks most of the time where system
gets frozen. With power domain state restored, system behaves correctly.

So update the code accordingly.

Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c
index 944e64a..9de47a7 100644 (file)
--- 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 (file)
--- 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)) {