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[CPUFREQ] update lpj only if frequency has changed

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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@ti.com>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Afzal Mohammed 2012-01-04 10:52:46 +05:30 committed by Dave Jones
parent 226dd0193f
commit d08de0c19c
1 changed files with 1 additions and 2 deletions
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3
drivers/cpufreq/cpufreq.c
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@ -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);