Hi,
Forwarding as the original is not yet seen in cpufreq archives.
Regards
Afzal
On Wed, Jan 04, 2012 at 10:52:31, Mohammed, Afzal wrote:
> 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@xxxxxx>
> ---
> 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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