diff options
| author | Will Deacon <will.deacon@arm.com> | 2013-03-28 11:17:55 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-04-03 17:45:50 +0200 |
| commit | 6f3d90e55660ba42301b5e9c7eed332cc9f70fd7 (patch) | |
| tree | 0f5ef09981f5322d80a79a12125d291adaab175b /arch/arm | |
| parent | ARM: 7684/1: errata: Workaround for Cortex-A15 erratum 798181 (TLBI/DSB opera... (diff) | |
| download | linux-6f3d90e55660ba42301b5e9c7eed332cc9f70fd7.tar.xz linux-6f3d90e55660ba42301b5e9c7eed332cc9f70fd7.zip | |
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 <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/include/asm/delay.h | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/smp.c | 3 | ||||
| -rw-r--r-- | 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 720799fd3a81..dff714d886d5 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 79078edbb9bc..1f2ccccaf009 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 6b93f6a1a3c7..64dbfa57204a 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"); |