From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH v3 1/3] cpufreq: add cpufreq_driver_resolve_freq() Date: Thu, 21 Jul 2016 22:31:18 +0200 Message-ID: <2012245.HQXNKhffmu@vostro.rjw.lan> References: <1468441527-23534-1-git-send-email-smuckle@linaro.org> <1468441527-23534-2-git-send-email-smuckle@linaro.org> <20160721195926.GF3122@ubuntu> 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]:41145 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753938AbcGUU0X (ORCPT ); Thu, 21 Jul 2016 16:26:23 -0400 In-Reply-To: <20160721195926.GF3122@ubuntu> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: Steve Muckle , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Vincent Guittot , Morten Rasmussen , Dietmar Eggemann , Juri Lelli , Patrick Bellasi , Steve Muckle On Thursday, July 21, 2016 12:59:26 PM Viresh Kumar wrote: > On 13-07-16, 13:25, Steve Muckle wrote: > > Cpufreq governors may need to know what a particular target frequency > > maps to in the driver without necessarily wanting to set the frequency. > > Support this operation via a new cpufreq API, > > cpufreq_driver_resolve_freq(). This API returns the lowest driver > > frequency equal or greater than the target frequency > > (CPUFREQ_RELATION_L), subject to any policy (min/max) or driver > > limitations. The mapping is also cached in the policy so that a > > subsequent fast_switch operation can avoid repeating the same lookup. > > > > The API will call a new cpufreq driver callback, resolve_freq(), if it > > has been registered by the driver. Otherwise the frequency is resolved > > via cpufreq_frequency_table_target(). Rather than require ->target() > > style drivers to provide a resolve_freq() callback it is left to the > > caller to ensure that the driver implements this callback if necessary > > to use cpufreq_driver_resolve_freq(). > > > > Suggested-by: Rafael J. Wysocki > > Signed-off-by: Steve Muckle > > --- > > drivers/cpufreq/cpufreq.c | 25 +++++++++++++++++++++++++ > > include/linux/cpufreq.h | 16 ++++++++++++++++ > > 2 files changed, 41 insertions(+) > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 118b4f30a406..b696baeb249d 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -492,6 +492,29 @@ void cpufreq_disable_fast_switch(struct cpufreq_policy *policy) > > } > > EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch); > > > > +/** > > + * cpufreq_driver_resolve_freq - Map a target frequency to a driver-supported > > + * one. > > + * @target_freq: target frequency to resolve. > > + * > > + * The target to driver frequency mapping is cached in the policy. > > + * > > + * Return: Lowest driver-supported frequency greater than or equal to the > > + * given target_freq, subject to policy (min/max) and driver limitations. > > + */ > > +unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy, > > + unsigned int target_freq) > > +{ > > + target_freq = clamp_val(target_freq, policy->min, policy->max); > > + policy->cached_target_freq = target_freq; > > + if (cpufreq_driver->resolve_freq) > > + return cpufreq_driver->resolve_freq(policy, target_freq); > > Any reason why we still have this call around ? I thought the whole > attempt I made was to get rid of this :) > > The core can do this pretty much now by itself, why do we still want > this call? In case some drivers that don't use frequency tables want to implemet fast switching, for example. > Also, your series doesn't add a user for it yet, so better drop it for > now. That's correct, but then it is not so much of a maintenance burden and I may need it. I'm going to apply the whole series. Thanks, Rafael