Re: [PATCH 2/6] cpufreq: Only query drivers that implement cpufreq_driver.target()

[Viresh Kumar]

On Sat, Feb 2, 2013 at 12:15 AM,  <dirk.brandewie@xxxxxxxxx> wrote:
> From: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>
>
> Scaling drivers that implement cpufreq_driver.setpolicy() have
> internal governors and may/will change the current operating frequency
> very frequently this will cause cpufreq_out_of_sync() to be called
> every time. Only call cpufreq_driver.get() for drivers that implement
> cpufreq_driver.target()
>
> Signed-off-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
> ---
>  drivers/cpufreq/cpufreq.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 1c037f0..493cd50 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1794,7 +1794,7 @@ int cpufreq_update_policy(unsigned int cpu)
>
>         /* BIOS might change freq behind our back
>           -> ask driver for current freq and notify governors about a change */
> -       if (cpufreq_driver->get) {
> +       if (cpufreq_driver->get && cpufreq_driver->target) {

This would mean policy->cur has a garbage value. I don't really know
how would other routine behave on this. Would it make sense to make
policy->cur zero atleast?
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