From 6f3d90e55660ba42301b5e9c7eed332cc9f70fd7 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 28 Mar 2013 11:17:55 +0100 Subject: [PATCH] ARM: 7685/1: delay: use private ticks_per_jiffy field for timer-based delay ops Commit 70264367a243 ("ARM: 7653/2: do not scale loops_per_jiffy when using a constant delay clock") fixed a problem with our timer-based delay loop, where loops_per_jiffy is scaled by cpufreq yet used directly by the timer delay ops. This patch fixes the problem in a more elegant way by keeping a private ticks_per_jiffy field in the delay ops, independent of loops_per_jiffy and therefore not subject to scaling. The loop-based delay continues to use loops_per_jiffy directly, as it should. Acked-by: Nicolas Pitre Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/include/asm/delay.h | 2 +- arch/arm/kernel/smp.c | 3 --- arch/arm/lib/delay.c | 8 +++++--- 3 files changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h index 720799fd3a8..dff714d886d 100644 --- a/arch/arm/include/asm/delay.h +++ b/arch/arm/include/asm/delay.h @@ -24,7 +24,7 @@ extern struct arm_delay_ops { void (*delay)(unsigned long); void (*const_udelay)(unsigned long); void (*udelay)(unsigned long); - bool const_clock; + unsigned long ticks_per_jiffy; } arm_delay_ops; #define __delay(n) arm_delay_ops.delay(n) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 79078edbb9b..1f2ccccaf00 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -673,9 +673,6 @@ static int cpufreq_callback(struct notifier_block *nb, if (freq->flags & CPUFREQ_CONST_LOOPS) return NOTIFY_OK; - if (arm_delay_ops.const_clock) - return NOTIFY_OK; - if (!per_cpu(l_p_j_ref, cpu)) { per_cpu(l_p_j_ref, cpu) = per_cpu(cpu_data, cpu).loops_per_jiffy; diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c index 6b93f6a1a3c..64dbfa57204 100644 --- a/arch/arm/lib/delay.c +++ b/arch/arm/lib/delay.c @@ -58,7 +58,7 @@ static void __timer_delay(unsigned long cycles) static void __timer_const_udelay(unsigned long xloops) { unsigned long long loops = xloops; - loops *= loops_per_jiffy; + loops *= arm_delay_ops.ticks_per_jiffy; __timer_delay(loops >> UDELAY_SHIFT); } @@ -73,11 +73,13 @@ void __init register_current_timer_delay(const struct delay_timer *timer) pr_info("Switching to timer-based delay loop\n"); delay_timer = timer; lpj_fine = timer->freq / HZ; - loops_per_jiffy = lpj_fine; + + /* cpufreq may scale loops_per_jiffy, so keep a private copy */ + arm_delay_ops.ticks_per_jiffy = lpj_fine; arm_delay_ops.delay = __timer_delay; arm_delay_ops.const_udelay = __timer_const_udelay; arm_delay_ops.udelay = __timer_udelay; - arm_delay_ops.const_clock = true; + delay_calibrated = true; } else { pr_info("Ignoring duplicate/late registration of read_current_timer delay\n"); -- 2.34.1