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authorMike Turquette <mturquette@linaro.org>2012-09-13 17:04:18 -0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-09-19 17:04:43 -0400
commit2b25d9f64b542cd19e020ce9d4d628c1feba96e5 (patch)
tree1b65a70ebfe9d03c884b57fcf63ff246da002f6d
parente1e5b7e4251c7538ca08c2c5545b0c2fbd8a6635 (diff)
ARM: 7535/1: Reprogram smp_twd based on new common clk framework notifiers
Running cpufreq driver on imx6q, the following warning is seen. $ BUG: sleeping function called from invalid context at kernel/mutex.c:269 <snip> 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 common clk users over to clk notifiers in place of CPUfreq notifiers. This works out nicely for Cortex-A9 MPcore designs that scale all CPUs at the same frequency. Platforms that have not been converted to the common clk framework and support CPUfreq will rely on the old mechanism. Once these platforms are converted over fully then we can remove the CPUfreq-specific bits for good. Signed-off-by: Mike Turquette <mturquette@linaro.org> Signed-off-by: Shawn Guo <shawn.guo@linaro.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/kernel/smp_twd.c48
1 files changed, 46 insertions, 2 deletions
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index fef42b21cecb..e1f906989bb8 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -11,7 +11,6 @@
11#include <linux/init.h> 11#include <linux/init.h>
12#include <linux/kernel.h> 12#include <linux/kernel.h>
13#include <linux/clk.h> 13#include <linux/clk.h>
14#include <linux/cpufreq.h>
15#include <linux/delay.h> 14#include <linux/delay.h>
16#include <linux/device.h> 15#include <linux/device.h>
17#include <linux/err.h> 16#include <linux/err.h>
@@ -96,7 +95,52 @@ static void twd_timer_stop(struct clock_event_device *clk)
96 disable_percpu_irq(clk->irq); 95 disable_percpu_irq(clk->irq);
97} 96}
98 97
99#ifdef CONFIG_CPU_FREQ 98#ifdef CONFIG_COMMON_CLK
99
100/*
101 * Updates clockevent frequency when the cpu frequency changes.
102 * Called on the cpu that is changing frequency with interrupts disabled.
103 */
104static void twd_update_frequency(void *new_rate)
105{
106 twd_timer_rate = *((unsigned long *) new_rate);
107
108 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
109}
110
111static int twd_rate_change(struct notifier_block *nb,
112 unsigned long flags, void *data)
113{
114 struct clk_notifier_data *cnd = data;
115
116 /*
117 * The twd clock events must be reprogrammed to account for the new
118 * frequency. The timer is local to a cpu, so cross-call to the
119 * changing cpu.
120 */
121 if (flags == POST_RATE_CHANGE)
122 smp_call_function(twd_update_frequency,
123 (void *)&cnd->new_rate, 1);
124
125 return NOTIFY_OK;
126}
127
128static struct notifier_block twd_clk_nb = {
129 .notifier_call = twd_rate_change,
130};
131
132static int twd_clk_init(void)
133{
134 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
135 return clk_notifier_register(twd_clk, &twd_clk_nb);
136
137 return 0;
138}
139core_initcall(twd_clk_init);
140
141#elif defined (CONFIG_CPU_FREQ)
142
143#include <linux/cpufreq.h>
100 144
101/* 145/*
102 * Updates clockevent frequency when the cpu frequency changes. 146 * Updates clockevent frequency when the cpu frequency changes.