From: Aaro Koskinen <aaro.koskinen@iki.fi>
Date: Mon, 30 Sep 2013 20:44:31 +0000 (+0300)
Subject: cpufreq: pmac64: speed up frequency switch
X-Git-Tag: v3.13-rc1~96^2~12^2~4^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=45a428ebbf7d6a4ec77cf02fc706ecd62b261bd9;p=pandora-kernel.git

cpufreq: pmac64: speed up frequency switch

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.koskinen@iki.fi>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

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