From c716483c3db10b31bf9bf43c5f45f2c3117ca13a Mon Sep 17 00:00:00 2001 From: Shawn Guo Date: Thu, 31 Jul 2014 02:07:37 +0100 Subject: [PATCH] ARM: 8122/1: smp_scu: enable SCU standby support With SCU standby enabled, SCU CLK will be turned off when all processors are in WFI mode. And the clock will be turned on when any processor leaves WFI mode. This behavior should be preferable in terms of power efficiency of system idle. So let's set the SCU standby bit to enable the support in function scu_enable(). Cortex-A9 earlier than r2p0 has no standby bit in SCU, so we need to skip setting the bit for those. Signed-off-by: Shawn Guo Acked-by: Soren Brinkmann Signed-off-by: Russell King --- arch/arm/kernel/smp_scu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c index c947508f84e6..72f9241ad5db 100644 --- a/arch/arm/kernel/smp_scu.c +++ b/arch/arm/kernel/smp_scu.c @@ -18,6 +18,7 @@ #define SCU_CTRL 0x00 #define SCU_ENABLE (1 << 0) +#define SCU_STANDBY_ENABLE (1 << 5) #define SCU_CONFIG 0x04 #define SCU_CPU_STATUS 0x08 #define SCU_INVALIDATE 0x0c @@ -55,6 +56,12 @@ void scu_enable(void __iomem *scu_base) return; scu_ctrl |= SCU_ENABLE; + + /* Cortex-A9 earlier than r2p0 has no standby bit in SCU */ + if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090 && + (read_cpuid_id() & 0x00f0000f) >= 0x00200000) + scu_ctrl |= SCU_STANDBY_ENABLE; + writel_relaxed(scu_ctrl, scu_base + SCU_CTRL); /* -- 2.20.1