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authorShawn Guo <shawn.guo@linaro.org>2012-08-18 14:27:32 +0800
committerShawn Guo <shawn.guo@linaro.org>2012-08-23 21:10:22 +0800
commitc944b0b9354ea06ffb0c8a7178949f1185f9f499 (patch)
tree6971c668617734f27ba86364c189c9dbecf8811c /arch/arm
parent16339464c5d67d0536837fc5342c9c2432b80ae0 (diff)
downloadlinux-linaro-stable-c944b0b9354ea06ffb0c8a7178949f1185f9f499.tar.gz
ARM: imx6: spin the cpu until hardware takes it down
Though commit 602bf40 (ARM: imx6: exit coherency when shutting down a cpu) improves the stability of imx6q cpu hotplug a lot, there are still hangs seen with a more stressful hotplug testing. It's expected that once imx_enable_cpu(cpu, false) is called, the cpu will be taken down by hardware immediately, and the code after that will not get any chance to execute. However, this is not always the case from the testing. The cpu could possibly be alive for a few cycles before hardware actually takes it down. So rather than letting cpu execute some code that could cause a hang in these cycles, let's make the cpu spin there and wait for hardware to take it down. Cc: <stable@vger.kernel.org> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mach-imx/hotplug.c23
1 files changed, 3 insertions, 20 deletions
diff --git a/arch/arm/mach-imx/hotplug.c b/arch/arm/mach-imx/hotplug.c
index 20ed2d56c1af..f8f7437c83b8 100644
--- a/arch/arm/mach-imx/hotplug.c
+++ b/arch/arm/mach-imx/hotplug.c
@@ -42,22 +42,6 @@ static inline void cpu_enter_lowpower(void)
: "cc");
}
-static inline void cpu_leave_lowpower(void)
-{
- unsigned int v;
-
- asm volatile(
- "mrc p15, 0, %0, c1, c0, 0\n"
- " orr %0, %0, %1\n"
- " mcr p15, 0, %0, c1, c0, 0\n"
- " mrc p15, 0, %0, c1, c0, 1\n"
- " orr %0, %0, %2\n"
- " mcr p15, 0, %0, c1, c0, 1\n"
- : "=&r" (v)
- : "Ir" (CR_C), "Ir" (0x40)
- : "cc");
-}
-
/*
* platform-specific code to shutdown a CPU
*
@@ -67,11 +51,10 @@ void platform_cpu_die(unsigned int cpu)
{
cpu_enter_lowpower();
imx_enable_cpu(cpu, false);
- cpu_do_idle();
- cpu_leave_lowpower();
- /* We should never return from idle */
- panic("cpu %d unexpectedly exit from shutdown\n", cpu);
+ /* spin here until hardware takes it down */
+ while (1)
+ ;
}
int platform_cpu_disable(unsigned int cpu)