From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 0/5] Switch to the DT cpufreq policy on the Integrator Date: Wed, 19 Oct 2016 23:24:21 +0200 Message-ID: <2560448.5arFO2Mb4U@vostro.rjw.lan> References: <1476871154-32243-1-git-send-email-linus.walleij@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from cloudserver094114.home.net.pl ([79.96.170.134]:54840 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753195AbcJSVR1 (ORCPT ); Wed, 19 Oct 2016 17:17:27 -0400 In-Reply-To: <1476871154-32243-1-git-send-email-linus.walleij@linaro.org> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Linus Walleij Cc: "Rafael J . Wysocki" , Viresh Kumar , linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Arnd Bergmann , Russell King On Wednesday, October 19, 2016 11:59:09 AM Linus Walleij wrote: > This switches the ARM Integrator/AP and Integrator/CP to use the > Device Tree cpufreq policy with its definition of operating points > using the generic OPP library. > > The Integrators does not need to control a regulator to switch > frequency, only a clock. This clock and its device tree bindings > have been defined in the device tree and merged upstream for v4.9. > > This approach provides a little better granularity on the > Integrator/AP where I defined a few operating points: before > this change the Integrator would just switch between min speed > (12 MHz) and max speed (71 MHz). Now it can switch between a > few arbitrarily chosen OPPs as in the examples below: > > The following tests were made on the Integrator/AP: > > /sys/devices/system/cpu/cpufreq/policy0 echo ondemand > scaling_governor > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 71000000 Hz --> 24000000 Hz > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 24000000 Hz --> 12000000 Hz > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 12000000 Hz --> 24000000 Hz > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 24000000 Hz --> 12000000 Hz > > The switch from 12 to 24 MHz is triggered by as little as using the > command line with the ondemand governor. If we do this: > > yes > /dev/null & > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 12000000 Hz --> 36000000 Hz > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 36000000 Hz --> 71000000 Hz > pkill yes > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 71000000 Hz --> 12000000 Hz > > So the algorithm is indeed using all the OPPs. > > Also as a confirmation test to make sure performance is affected by the > speed changes, we set the performance governor and: > > echo 12000 > scaling_max_freq > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 71000000 Hz --> 12000000 Hz > time find /sys|sort|uniq > /dev/null > real 0m 45.51s > user 0m 11.15s > sys 0m 26.74s > > echo 71000 > scaling_max_freq > cpu cpu0: dev_pm_opp_set_rate: switching OPP: 12000000 Hz --> 71000000 Hz > time find /sys|sort|uniq > > /dev/null > real 0m 9.13s > user 0m 2.35s > sys 0m 5.50s > > So it is working. > > If people are happy with this approach and approve of the patches > I'd like an ACK from the cpufreq people and then merge the whole set > through ARM SoC. > > Linus Walleij (5): > cpufreq: enable the DT cpufreq driver on the Integrators > ARM: dts: Add Integrator/AP cpus node and operating points > ARM: dts: Add Integrator/CP cpus node and operating points > ARM: defconfig: turn on the DT cpufreq for Integrator > cpufreq: retire the Integrator cpufreq driver The cpufreq changes look good to me, but Viresh is the expert for the DT stuff. Thanks, Rafael