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authorWill Deacon <will.deacon@arm.com>2013-03-28 11:17:55 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-04-03 16:45:50 +0100
commit6f3d90e55660ba42301b5e9c7eed332cc9f70fd7 (patch)
tree0f5ef09981f5322d80a79a12125d291adaab175b /arch
parent93dc68876b608da041fe40ed39424b0fcd5aa2fb (diff)
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')
-rw-r--r--arch/arm/include/asm/delay.h2
-rw-r--r--arch/arm/kernel/smp.c3
-rw-r--r--arch/arm/lib/delay.c8
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");