[RESEND PATCH] ARM: EXYNOS: Fix failed second suspend on Exynos4

Krzysztof Kozlowski
2015-02-18T10:45:39Z

On Exynos4412 boards (Trats2, Odroid U3) after enabling L2 cache in
56b60b8bce4a ("ARM: 8265/1: dts: exynos4: Add nodes for L2 cache
controller") the second suspend to RAM failed. First suspend worked fine
but the next one hang just after powering down of secondary CPUs (system
consumed energy as it would be running but was not responsive).

The issue was caused by enabling delayed reset assertion for CPU0 just
after issuing power down of cores. This was introduced for Exynos4 in
13cfa6c4f7fa ("ARM: EXYNOS: Fix CPU idle clock down after CPU off").

The whole behavior is not well documented but after checking with vendor
code this should be done like this (on Exynos4):
1. Enable delayed reset assertion when system is running (for all CPUs).
2. Disable delayed reset assertion before suspending the system.
This can be done after powering off secondary CPUs.
3. Re-enable the delayed reset assertion when system is resumed.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: 13cfa6c4f7fa ("ARM: EXYNOS: Fix CPU idle clock down after CPU off")
Cc: <stable@vger.kernel.org>
---
arch/arm/mach-exynos/common.h | 2 ++
arch/arm/mach-exynos/exynos.c | 27 +++++++++++++++++++++++++++
arch/arm/mach-exynos/platsmp.c | 39 ++-------------------------------------
arch/arm/mach-exynos/suspend.c | 3 +++
4 files changed, 34 insertions(+), 37 deletions(-)

diff --git a/arch/arm/mach-exynos/common.h b/arch/arm/mach-exynos/common.h
index f70eca7ee705..0ef8d4b47102 100644
--- a/arch/arm/mach-exynos/common.h
+++ b/arch/arm/mach-exynos/common.h
@@ -153,6 +153,8 @@ extern void exynos_enter_aftr(void);

extern struct cpuidle_exynos_data cpuidle_coupled_exynos_data;

+extern void exynos_set_delayed_reset_assertion(bool enable);
+
extern void s5p_init_cpu(void __iomem *cpuid_addr);
extern unsigned int samsung_rev(void);
extern void __iomem *cpu_boot_reg_base(void);
diff --git a/arch/arm/mach-exynos/exynos.c b/arch/arm/mach-exynos/exynos.c
index 2013f73797ed..e2f46295eed7 100644
--- a/arch/arm/mach-exynos/exynos.c
+++ b/arch/arm/mach-exynos/exynos.c
@@ -166,6 +166,33 @@ static void __init exynos_init_io(void)
exynos_map_io();
}

+/*
+ * Set or clear the USE_DELAYED_RESET_ASSERTION option. Used by smp code
+ * and suspend.
+ *
+ * This is necessary only on Exynos4 SoCs. When system is running
+ * USE_DELAYED_RESET_ASSERTION should be set so the ARM CLK clock down
+ * feature could properly detect global idle state when secondary CPU is
+ * powered down.
+ *
+ * However this should not be set when such system is going into suspend.
+ */
+void exynos_set_delayed_reset_assertion(bool enable)
+{
+ if (soc_is_exynos4()) {
+ unsigned int tmp, core_id;
+
+ for (core_id = 0; core_id < num_possible_cpus(); core_id++) {
+ tmp = pmu_raw_readl(EXYNOS_ARM_CORE_OPTION(core_id));
+ if (enable)
+ tmp |= S5P_USE_DELAYED_RESET_ASSERTION;
+ else
+ tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION);
+ pmu_raw_writel(tmp, EXYNOS_ARM_CORE_OPTION(core_id));
+ }
+ }
+}
+
static const struct of_device_id exynos_dt_pmu_match[] = {
{ .compatible = "samsung,exynos3250-pmu" },
{ .compatible = "samsung,exynos4210-pmu" },
diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index 3f32c47a6d74..19d5c87c842c 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -34,30 +34,6 @@

extern void exynos4_secondary_startup(void);

-/*
- * Set or clear the USE_DELAYED_RESET_ASSERTION option, set on Exynos4 SoCs
- * during hot-(un)plugging CPUx.
- *
- * The feature can be cleared safely during first boot of secondary CPU.
- *
- * Exynos4 SoCs require setting USE_DELAYED_RESET_ASSERTION during powering
- * down a CPU so the CPU idle clock down feature could properly detect global
- * idle state when CPUx is off.
- */
-static void exynos_set_delayed_reset_assertion(u32 core_id, bool enable)
-{
- if (soc_is_exynos4()) {
- unsigned int tmp;
-
- tmp = pmu_raw_readl(EXYNOS_ARM_CORE_OPTION(core_id));
- if (enable)
- tmp |= S5P_USE_DELAYED_RESET_ASSERTION;
- else
- tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION);
- pmu_raw_writel(tmp, EXYNOS_ARM_CORE_OPTION(core_id));
- }
-}
-
#ifdef CONFIG_HOTPLUG_CPU
static inline void cpu_leave_lowpower(u32 core_id)
{
@@ -73,8 +49,6 @@ static inline void cpu_leave_lowpower(u32 core_id)
: "=&r" (v)
: "Ir" (CR_C), "Ir" (0x40)
: "cc");
-
- exynos_set_delayed_reset_assertion(core_id, false);
}

static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
@@ -87,14 +61,6 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
/* Turn the CPU off on next WFI instruction. */
exynos_cpu_power_down(core_id);

- /*
- * Exynos4 SoCs require setting
- * USE_DELAYED_RESET_ASSERTION so the CPU idle
- * clock down feature could properly detect
- * global idle state when CPUx is off.
- */
- exynos_set_delayed_reset_assertion(core_id, true);
-
wfi();

if (pen_release == core_id) {
@@ -355,9 +321,6 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
udelay(10);
}

- /* No harm if this is called during first boot of secondary CPU */
- exynos_set_delayed_reset_assertion(core_id, false);
-
/*
* now the secondary core is starting up let it run its
* calibrations, then wait for it to finish
@@ -404,6 +367,8 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)

exynos_sysram_init();

+ exynos_set_delayed_reset_assertion(true);
+
if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9)
scu_enable(scu_base_addr());

diff --git a/arch/arm/mach-exynos/suspend.c b/arch/arm/mach-exynos/suspend.c
index 666ec3e5b03f..d4da035cc88a 100644
--- a/arch/arm/mach-exynos/suspend.c
+++ b/arch/arm/mach-exynos/suspend.c
@@ -235,6 +235,8 @@ static void exynos_pm_enter_sleep_mode(void)

static void exynos_pm_prepare(void)
{
+ exynos_set_delayed_reset_assertion(false);
+
/* Set wake-up mask registers */
exynos_pm_set_wakeup_mask();

@@ -383,6 +385,7 @@ early_wakeup:

/* Clear SLEEP mode set in INFORM1 */
pmu_raw_writel(0x0, S5P_INFORM1);
+ exynos_set_delayed_reset_assertion(true);
}

static void exynos3250_pm_resume(void)
--
1.9.1