Some functions on switch path use msleep() which is inaccurate, and
depends on HZ. With HZ=100 msleep(1) takes actually over ten times longer.
Using usleep_range() we get more accurate sleeps.
I measured the "pfunc_slewing_done" polling to take 300us at max (on
2.3GHz dual-processor Xserve G5), so using 500us sleep there should
be fine.
With the patch, g5_switch_freq() duration drops from ~50ms to ~10ms on
Xserve with HZ=100.
Signed-off-by: Aaro Koskinen <aaro.koski...@iki.fi>
Acked-by: Viresh Kumar <viresh.ku...@linaro.org>
---
drivers/cpufreq/pmac64-cpufreq.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/cpufreq/pmac64-cpufreq.c b/drivers/cpufreq/pmac64-cpufreq.c
index 3a51ad7..46ae223 100644
--- a/drivers/cpufreq/pmac64-cpufreq.c
+++ b/drivers/cpufreq/pmac64-cpufreq.c
@@ -142,7 +142,7 @@ static void g5_vdnap_switch_volt(int speed_mode)
pmf_call_one(pfunc_vdnap0_complete, &args);
if (done)
break;
- msleep(1);
+ usleep_range(1000, 1000);
}
if (done == 0)
printk(KERN_WARNING "cpufreq: Timeout in clock slewing !\n");
@@ -241,7 +241,7 @@ static void g5_pfunc_switch_volt(int speed_mode)
if (pfunc_cpu1_volt_low)
pmf_call_one(pfunc_cpu1_volt_low, NULL);
}
- msleep(10); /* should be faster , to fix */
+ usleep_range(10000, 10000); /* should be faster , to fix */
}
/*
@@ -286,7 +286,7 @@ static int g5_pfunc_switch_freq(int speed_mode)
pmf_call_one(pfunc_slewing_done, &args);
if (done)
break;
- msleep(1);
+ usleep_range(500, 500);
}
if (done == 0)
printk(KERN_WARNING "cpufreq: Timeout in clock slewing !\n");
--
1.8.4.rc3
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