Merge tag 'imx-fixes-3.9-4' of git://git.linaro.org/people/shawnguo/linux-2.6 into fixes

From Shawn Guo <shawn.guo@linaro.org>:

The imx fixes for 3.9, take 4:

Running suspend/resume without no_console_suspend setting on kernel
cmdline will likely makes system hang.  It causesd by the sync issue
between imx_cpu_die() and imx_cpu_kill() call.  Fix the issue by
synchronizing the calls using cpu jumping argument register which is
free to use in kernel.

* tag 'imx-fixes-3.9-4' of git://git.linaro.org/people/shawnguo/linux-2.6:
  ARM: imx: fix sync issue between imx_cpu_die and imx_cpu_kill
  ARM: imx: add dependency check for DEBUG_IMX_UART_PORT
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/Kconfig.debug

@@ -495,6 +495,7 @@ config DEBUG_IMX_UART_PORT
 						DEBUG_IMX53_UART || \
 						DEBUG_IMX6Q_UART
 	default 1
+	depends on ARCH_MXC
 	help
 	  Choose UART port on which kernel low-level debug messages
 	  should be output.

arch/arm/mach-imx/common.h

@@ -110,6 +110,8 @@ 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);
 extern void v7_cpu_resume(void);
 extern u32 *pl310_get_save_ptr(void);
 #ifdef CONFIG_SMP

arch/arm/mach-imx/hotplug.c

@@ -46,11 +46,23 @@ static inline void cpu_enter_lowpower(void)
 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;
 }

arch/arm/mach-imx/src.c

@@ -43,6 +43,18 @@ void imx_set_cpu_jump(int cpu, void *jump_addr)
 		       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;