3.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shawn Guo <shawn....@linaro.org>
commit 2f3edfd7e27ad4206acbc2ae99c9df5f46353024 upstream.
There is a sync issue with hotplug operation. It's possible that when
imx_cpu_kill gets running on primary core, the imx_cpu_die execution
on the core which is to be killed hasn't been finished yet. The problem
will very likely be hit when running suspend without no_console_suspend
setting on kernel cmdline.
It uses cpu jumping argument register to sync imx_cpu_die and
imx_cpu_kill. The register will be set in imx_cpu_die and imx_cpu_kill
will wait for the register being cleared to actually kill the cpu.
Signed-off-by: Shawn Guo <shawn....@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/arm/mach-imx/common.h | 2 ++
arch/arm/mach-imx/hotplug.c | 12 ++++++++++++
arch/arm/mach-imx/src.c | 12 ++++++++++++
3 files changed, 26 insertions(+)
--- a/arch/arm/mach-imx/common.h
+++ b/arch/arm/mach-imx/common.h
@@ -116,6 +116,8 @@ void tzic_handle_irq(struct pt_regs *);
extern void imx_enable_cpu(int cpu, bool enable);
extern void imx_set_cpu_jump(int cpu, void *jump_addr);
+extern u32 imx_get_cpu_arg(int cpu);
+extern void imx_set_cpu_arg(int cpu, u32 arg);
#ifdef CONFIG_DEBUG_LL
extern void imx_lluart_map_io(void);
#else
--- a/arch/arm/mach-imx/hotplug.c
+++ b/arch/arm/mach-imx/hotplug.c
@@ -46,11 +46,23 @@ static inline void cpu_enter_lowpower(vo
void imx_cpu_die(unsigned int cpu)
{
cpu_enter_lowpower();
+ /*
+ * We use the cpu jumping argument register to sync with
+ * imx_cpu_kill() which is running on cpu0 and waiting for
+ * the register being cleared to kill the cpu.
+ */
+ imx_set_cpu_arg(cpu, ~0);
cpu_do_idle();
}
int imx_cpu_kill(unsigned int cpu)
{
+ unsigned long timeout = jiffies + msecs_to_jiffies(50);
+
+ while (imx_get_cpu_arg(cpu) == 0)
+ if (time_after(jiffies, timeout))
+ return 0;
imx_enable_cpu(cpu, false);
+ imx_set_cpu_arg(cpu, 0);
return 1;
}
--- a/arch/arm/mach-imx/src.c
+++ b/arch/arm/mach-imx/src.c
@@ -43,6 +43,18 @@ void imx_set_cpu_jump(int cpu, void *jum
src_base + SRC_GPR1 + cpu * 8);
}
+u32 imx_get_cpu_arg(int cpu)
+{
+ cpu = cpu_logical_map(cpu);
+ return readl_relaxed(src_base + SRC_GPR1 + cpu * 8 + 4);
+}
+
+void imx_set_cpu_arg(int cpu, u32 arg)
+{
+ cpu = cpu_logical_map(cpu);
+ writel_relaxed(arg, src_base + SRC_GPR1 + cpu * 8 + 4);
+}
+
void imx_src_prepare_restart(void)
{
u32 val;
--
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