[PATCH] ARM: exynos4212: hotplug: Fix CPU idle clock down after CPU1 off

On pi?, 2014-05-30 at 13:50 +0200, Tomasz Figa wrote:

Hi Krzysztof,

On 13.05.2014 16:12, Krzysztof Kozlowski wrote:

quoted

On Exynos4212 USE_DELAYED_RESET_ASSERTION must be set in
ARM_CORE1_OPTION register during CPU power down. This is the proper way
of powering down CPU. Additionally without this the CPU clock down won't
work after powering down CPU1 and CPU will work at full frequency chosen
by CPUfreq governor.

Signed-off-by: Krzysztof Kozlowski <redacted>
---
 arch/arm/mach-exynos/hotplug.c  | 28 +++++++++++++++++++++++++---
 arch/arm/mach-exynos/regs-pmu.h |  2 ++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
index 5eead530c6f8..59b813e74558 100644
--- a/arch/arm/mach-exynos/hotplug.c
+++ b/arch/arm/mach-exynos/hotplug.c

@@ -74,7 +74,7 @@ static inline void cpu_enter_lowpower_a15(void)
 	dsb();
 }
 
-static inline void cpu_leave_lowpower(void)
+static inline void cpu_leave_lowpower(unsigned int cpu)
 {
 	unsigned int v;
 

@@ -88,6 +88,14 @@ static inline void cpu_leave_lowpower(void)
 	  : "=&r" (v)
 	  : "Ir" (CR_C), "Ir" (0x40)
 	  : "cc");
+
+	if (cpu == 1 && soc_is_exynos4212()) {

AFAIK this is needed not only on Exynos4x12, but at least also on 4412.
Also I don't think the (cpu == 1) condition is necessary. See below.

I'll test it on Exynos4412.

quoted

+		unsigned int tmp;
+
+		tmp = __raw_readl(S5P_ARM_CORE1_OPTION);
+		tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION);
+		__raw_writel(tmp, S5P_ARM_CORE1_OPTION);
+	}
 }
 
 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)

@@ -95,8 +103,22 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
 	for (;;) {
 
 		/* make cpu1 to be turned off at next WFI command */
-		if (cpu == 1)
+		if (cpu == 1) {

I think this patch should be rebased on top of my "[PATCH] ARM: EXYNOS:
Fix core ID used by platsmp and hotplug code". Then instead of if (cpu
== 1) you would just use EXYNOS_ARM_CORE_OPTION(core_id).

Also same comment as above, I believe this is also needed on Exynos4412.

Probably your patch needs rebasing too. I couldn't apply (cleanly) on
current Linus' tree and on Kukjin's for-next. What are the requirements
for it?

Best regards,
Krzysztof