From mboxrd@z Thu Jan 1 00:00:00 1970 From: shawn.guo@linaro.org (Shawn Guo) Date: Mon, 14 Jan 2013 21:09:37 +0800 Subject: [PATCH] ARM: imx: disable cpu in .cpu_kill hook Message-ID: <1358168977-9631-1-git-send-email-shawn.guo@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org It's buggy to disable the cpu that is being hot-unplugged in .cpu_die hook which runs on the cpu itself. Instead, it should be done in .cpu_kill which runs on the thread (another cpu) that asks for shutting down the cpu. Move imx_enable_cpu(cpu, false) call into .cpu_kill hook, and leave the cpu to be hot-unplugged in WFI with a recovery call cpu_leave_lowpower(), so that we can get a more stable cpu hot-plug operation. Signed-off-by: Shawn Guo --- arch/arm/mach-imx/common.h | 1 + arch/arm/mach-imx/hotplug.c | 31 +++++++++++++++++++++++++++---- arch/arm/mach-imx/platsmp.c | 1 + 3 files changed, 29 insertions(+), 4 deletions(-) diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h index 7191ab4..fa36fb8 100644 --- a/arch/arm/mach-imx/common.h +++ b/arch/arm/mach-imx/common.h @@ -142,6 +142,7 @@ extern int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode); extern void imx6q_clock_map_io(void); extern void imx_cpu_die(unsigned int cpu); +extern int imx_cpu_kill(unsigned int cpu); #ifdef CONFIG_PM extern void imx6q_pm_init(void); diff --git a/arch/arm/mach-imx/hotplug.c b/arch/arm/mach-imx/hotplug.c index 3dec962..a9b4096 100644 --- a/arch/arm/mach-imx/hotplug.c +++ b/arch/arm/mach-imx/hotplug.c @@ -38,6 +38,22 @@ 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 * @@ -45,10 +61,17 @@ static inline void cpu_enter_lowpower(void) */ void imx_cpu_die(unsigned int cpu) { + static int spurious; + cpu_enter_lowpower(); - imx_enable_cpu(cpu, false); + cpu_do_idle(); + cpu_leave_lowpower(); - /* spin here until hardware takes it down */ - while (1) - ; + pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, ++spurious); +} + +int imx_cpu_kill(unsigned int cpu) +{ + imx_enable_cpu(cpu, false); + return 1; } diff --git a/arch/arm/mach-imx/platsmp.c b/arch/arm/mach-imx/platsmp.c index 3777b80..66fae88 100644 --- a/arch/arm/mach-imx/platsmp.c +++ b/arch/arm/mach-imx/platsmp.c @@ -92,5 +92,6 @@ struct smp_operations imx_smp_ops __initdata = { .smp_boot_secondary = imx_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU .cpu_die = imx_cpu_die, + .cpu_kill = imx_cpu_kill, #endif }; -- 1.7.9.5