update lpj only if frequency has changed
authorAfzal Mohammed <afzal@ti.com>
Wed, 4 Jan 2012 05:22:46 +0000 (10:52 +0530)
committerVaibhav Hiremath <hvaibhav@ti.com>
Mon, 23 Jan 2012 19:14:51 +0000 (00:44 +0530)
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>
drivers/cpufreq/cpufreq.c

index 987a165ede2686ef8de37b7e72a1426e40b9ed25..2f5801adc7391f507e3f1f84dac07b2bd32af660 100644 (file)
@@ -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);