From mboxrd@z Thu Jan 1 00:00:00 1970 From: shawn.guo@linaro.org (Shawn Guo) Date: Fri, 7 Sep 2012 16:19:27 +0800 Subject: [PATCH] ARM: smp_twd: reprogram twd based on clk notifier Message-ID: <1347005967-7604-1-git-send-email-shawn.guo@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Mike Turquette Running cpufreq driver on imx6q, the following warning is seen. $ BUG: sleeping function called from invalid context at kernel/mutex.c:269 stack backtrace: Backtrace: [<80011d64>] (dump_backtrace+0x0/0x10c) from [<803fc164>] (dump_stack+0x18/0x1c) r6:bf8142e0 r5:bf814000 r4:806ac794 r3:bf814000 [<803fc14c>] (dump_stack+0x0/0x1c) from [<803fd444>] (print_usage_bug+0x250/0x2b 8) [<803fd1f4>] (print_usage_bug+0x0/0x2b8) from [<80060f90>] (mark_lock+0x56c/0x67 0) [<80060a24>] (mark_lock+0x0/0x670) from [<80061a20>] (__lock_acquire+0x98c/0x19b 4) [<80061094>] (__lock_acquire+0x0/0x19b4) from [<80062f14>] (lock_acquire+0x68/0x 7c) [<80062eac>] (lock_acquire+0x0/0x7c) from [<80400f28>] (mutex_lock_nested+0x78/0 x344) r7:00000000 r6:bf872000 r5:805cc858 r4:805c2a04 [<80400eb0>] (mutex_lock_nested+0x0/0x344) from [<803089ac>] (clk_get_rate+0x1c/ 0x58) [<80308990>] (clk_get_rate+0x0/0x58) from [<80013c48>] (twd_update_frequency+0x1 8/0x50) r5:bf253d04 r4:805cadf4 [<80013c30>] (twd_update_frequency+0x0/0x50) from [<80068e20>] (generic_smp_call _function_single_interrupt+0xd4/0x13c) r4:bf873ee0 r3:80013c30 [<80068d4c>] (generic_smp_call_function_single_interrupt+0x0/0x13c) from [<80013 34c>] (handle_IPI+0xc0/0x194) r8:00000001 r7:00000000 r6:80574e48 r5:bf872000 r4:80593958 [<8001328c>] (handle_IPI+0x0/0x194) from [<800084e8>] (gic_handle_irq+0x58/0x60) r8:00000000 r7:bf873f8c r6:bf873f58 r5:80593070 r4:f4000100 r3:00000005 [<80008490>] (gic_handle_irq+0x0/0x60) from [<8000e124>] (__irq_svc+0x44/0x60) Exception stack(0xbf873f58 to 0xbf873fa0) 3f40: 00000001 00000001 3f60: 00000000 bf814000 bf872000 805cab48 80405aa4 80597648 00000000 412fc09a 3f80: bf872000 bf873fac bf873f70 bf873fa0 80063844 8000f1f8 20000013 ffffffff r6:ffffffff r5:20000013 r4:8000f1f8 r3:bf814000 [<8000f1b8>] (default_idle+0x0/0x4c) from [<8000f428>] (cpu_idle+0x98/0x114) [<8000f390>] (cpu_idle+0x0/0x114) from [<803f9834>] (secondary_start_kernel+0x11 c/0x140) [<803f9718>] (secondary_start_kernel+0x0/0x140) from [<103f9234>] (0x103f9234) r6:10c03c7d r5:0000001f r4:4f86806a r3:803f921c It looks that the warning is caused by that twd_update_frequency() gets called from an atomic context while it calls clk_get_rate() where a mutex gets held. To fix the warning, let's convert the existing code to use clk notifiers in place of CPUfreq notifiers. This works out nicely for Cortex-A9 MPcore designs that scale all CPUs at the same frequency. Signed-off-by: Mike Turquette Signed-off-by: Shawn Guo --- arch/arm/kernel/smp_twd.c | 32 +++++++++++++------------------- 1 files changed, 13 insertions(+), 19 deletions(-) diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index fef42b2..635e3ea 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -11,7 +11,6 @@ #include #include #include -#include #include #include #include @@ -96,51 +95,46 @@ static void twd_timer_stop(struct clock_event_device *clk) disable_percpu_irq(clk->irq); } -#ifdef CONFIG_CPU_FREQ - /* * Updates clockevent frequency when the cpu frequency changes. * Called on the cpu that is changing frequency with interrupts disabled. */ -static void twd_update_frequency(void *data) +static void twd_update_frequency(void *new_rate) { - twd_timer_rate = clk_get_rate(twd_clk); + twd_timer_rate = *((unsigned long *) new_rate); clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate); } -static int twd_cpufreq_transition(struct notifier_block *nb, - unsigned long state, void *data) +static int twd_rate_change(struct notifier_block *nb, + unsigned long flags, void *data) { - struct cpufreq_freqs *freqs = data; + struct clk_notifier_data *cnd = data; /* * The twd clock events must be reprogrammed to account for the new * frequency. The timer is local to a cpu, so cross-call to the * changing cpu. */ - if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE) - smp_call_function_single(freqs->cpu, twd_update_frequency, - NULL, 1); + if (flags == POST_RATE_CHANGE) + smp_call_function(twd_update_frequency, + (void *)&cnd->new_rate, 1); return NOTIFY_OK; } -static struct notifier_block twd_cpufreq_nb = { - .notifier_call = twd_cpufreq_transition, +static struct notifier_block twd_clk_nb = { + .notifier_call = twd_rate_change, }; -static int twd_cpufreq_init(void) +static int twd_clk_init(void) { if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) - return cpufreq_register_notifier(&twd_cpufreq_nb, - CPUFREQ_TRANSITION_NOTIFIER); + return clk_notifier_register(twd_clk, &twd_clk_nb); return 0; } -core_initcall(twd_cpufreq_init); - -#endif +core_initcall(twd_clk_init); static void __cpuinit twd_calibrate_rate(void) { -- 1.7.5.4