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From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Andreas Herrmann <aherrmann@suse.com>,
	Jacob Tanenbaum <jtanenba@redhat.com>,
	stable@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency"
Date: Fri, 22 Jul 2016 16:30:42 -0700	[thread overview]
Message-ID: <20160722233042.GI3122@ubuntu> (raw)
In-Reply-To: <3860863.MLaNBM27lJ@vostro.rjw.lan>

On 22-07-16, 23:46, Rafael J. Wysocki wrote:
> On Friday, July 22, 2016 02:28:52 PM Viresh Kumar wrote:
> > On 22-07-16, 23:31, Rafael J. Wysocki wrote:
> > > > cpufreq.c
> > > > 
> > > > 	if (policy->governor->max_transition_latency &&
> > > > 	    policy->cpuinfo.transition_latency >
> > > > 	    policy->governor->max_transition_latency) {
> > > > 
> > > > - And this check will always fail, unless max_transition_latency is zero.
> > > 
> > > Why would it fail?  If governor->max_transition_latency is non-zero, but less
> > > than UNIT_MAX, the condition checked will be true to my eyes.
> > 
> > Bad wording. Sorry.
> > 
> > I meant, this 'if' check will always succeed (as you also noted), and
> > so we will always get the error message reported in this patch.
> 
> Not always, but for drivers setting cpuinfo.transition_latency to CPUFREQ_ETERNAL.

So the drivers which have set their transition_latency to
CPUFREQ_ETERNAL, can't use ondemand governor unless
governor->max_transition_latency is set to 0 from userspace.

What should be done about this patch then ? It broke in late 2015.

-- 
viresh

  reply	other threads:[~2016-07-22 23:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-22 15:14 [PATCH] Revert "cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency" Andreas Herrmann
2016-07-22 15:36 ` Viresh Kumar
2016-07-22 19:25   ` Linda Knippers
2016-07-22 21:16     ` Linda Knippers
2016-07-22 21:31   ` Rafael J. Wysocki
2016-07-22 21:28     ` Viresh Kumar
2016-07-22 21:46       ` Rafael J. Wysocki
2016-07-22 23:30         ` Viresh Kumar [this message]
2016-07-22 23:47           ` Rafael J. Wysocki
2016-07-22 23:50             ` Viresh Kumar

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