path: root/arch/arm/kernel/smp.c
diff options
authorNicolas Pitre <nicolas.pitre@linaro.org>2013-02-18 16:36:13 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-02-21 13:25:36 +0000
commit70264367a243a68b1d5636ffb570183449803cbe (patch)
treed5ab3e7434c916f97b2e22fee6dd48c7cc9c416c /arch/arm/kernel/smp.c
parent7c4e9ced424be4d36df6a3e3825763e97ee97607 (diff)
ARM: 7653/2: do not scale loops_per_jiffy when using a constant delay clock
When udelay() is implemented using an architected timer, it is wrong to scale loops_per_jiffy when changing the CPU clock frequency since the timer clock remains constant. The lpj should probably become an implementation detail relevant to the CPU loop based delay routine only and more confined to it. In the mean time this is the minimal fix needed to have expected delays with the timer based implementation when cpufreq is also in use. Reported-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Tested-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Liviu Dudau <Liviu.Dudau@arm.com> Cc: stable@vger.kernel.org Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/smp.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 84f4cbf652e..58af91c2a2f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -693,6 +693,9 @@ 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;