Hi,
Forwarding as the original is not yet seen in cpufreq archives.
Regards
Afzal
On Wed, Jan 04, 2012 at 10:52:46, Mohammed, Afzal wrote:
> During scaling up of cpu frequency, loops_per_jiffy
> is updated upon invoking PRECHANGE notifier.
> If setting to new frequency fails in cpufreq driver,
> lpj is left at incorrect value.
>
> Hence update lpj only if cpu frequency is changed,
> i.e. upon invoking POSTCHANGE notifier.
>
> Penalty would be that during time period between
> changing cpu frequency & invocation of POSTCHANGE
> notifier, udelay(x) may not gurantee minimal delay
> of 'x' us for frequency scaling up operation.
>
> Perhaps a better solution would be to define
> CPUFREQ_ABORTCHANGE & handle accordingly, but then
> it would be more intrusive (using ABORTCHANGE may
> help drivers also; if any has registered notifier
> and expect POST for a PRECHANGE, their needs can
> be taken care using ABORT)
>
> Signed-off-by: Afzal Mohammed <afzal@xxxxxx>
> ---
> drivers/cpufreq/cpufreq.c | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 987a165..2f5801a 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -204,8 +204,7 @@ static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
> pr_debug("saving %lu as reference value for loops_per_jiffy; "
> "freq is %u kHz\n", l_p_j_ref, l_p_j_ref_freq);
> }
> - if ((val == CPUFREQ_PRECHANGE && ci->old < ci->new) ||
> - (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
> + if ((val == CPUFREQ_POSTCHANGE && ci->old != ci->new) ||
> (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
> loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
> ci->new);
> --
> 1.7.1
>
>
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