Messages in this thread Patch in this message | | | From | Afzal Mohammed <> | Subject | [PATCH 1/2] cpufreq:userspace: fix cpu_cur_freq updation | Date | Wed, 4 Jan 2012 10:52:31 +0530 |
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CPU frequency is guranteed to be changed on notifier callback with CPUFREQ_POSTCHANGE. Notifier callback with CPUFREQ_PRECHANGE does not gurantee a change in frequency; after it, if cpufreq driver is unable to change CPU to new frequency. This results in wrong information being fed to user (if setting CPU frequency fails) upon doing like,
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
Hence in userspace governer update cpu_cur_freq only if notifier has been called with POSTCHANGE.
Signed-off-by: Afzal Mohammed <afzal@ti.com> --- drivers/cpufreq/cpufreq_userspace.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_userspace.c b/drivers/cpufreq/cpufreq_userspace.c index f231015..bedac1a 100644 --- a/drivers/cpufreq/cpufreq_userspace.c +++ b/drivers/cpufreq/cpufreq_userspace.c @@ -47,9 +47,11 @@ userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val, if (!per_cpu(cpu_is_managed, freq->cpu)) return 0; - pr_debug("saving cpu_cur_freq of cpu %u to be %u kHz\n", - freq->cpu, freq->new); - per_cpu(cpu_cur_freq, freq->cpu) = freq->new; + if (val == CPUFREQ_POSTCHANGE) { + pr_debug("saving cpu_cur_freq of cpu %u to be %u kHz\n", + freq->cpu, freq->new); + per_cpu(cpu_cur_freq, freq->cpu) = freq->new; + } return 0; } -- 1.7.1
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