Re: [PATCH V4 3/3] cpufreq: Specify default governor on command line

From: Quentin Perret <qperret@google.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-pm@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>,
	kernel-team@android.com, tkjos@google.com,
	adharmap@codeaurora.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V4 3/3] cpufreq: Specify default governor on command line
Date: Mon, 29 Jun 2020 10:50:38 +0100	[thread overview]
Message-ID: <20200629095038.GB1231692@google.com> (raw)
In-Reply-To: <20200629094825.GA1231692@google.com>

On Monday 29 Jun 2020 at 10:48:25 (+0100), Quentin Perret wrote:
> On Monday 29 Jun 2020 at 15:16:27 (+0530), Viresh Kumar wrote:
> > On 29-06-20, 10:44, Quentin Perret wrote:
> > > On Monday 29 Jun 2020 at 13:55:00 (+0530), Viresh Kumar wrote:
> > > >  static int __init cpufreq_core_init(void)
> > > >  {
> > > > +	struct cpufreq_governor *gov = cpufreq_default_governor();
> > > > +
> > > >  	if (cpufreq_disabled())
> > > >  		return -ENODEV;
> > > >  
> > > >  	cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj);
> > > >  	BUG_ON(!cpufreq_global_kobject);
> > > >  
> > > > +	if (!strlen(default_governor))
> > > 
> > > Should we test '!strlen(default_governor) && gov' here actually?
> > > We check the return value of cpufreq_default_governor() in
> > > cpufreq_init_policy(), so I'm guessing we should do the same here to be
> > > on the safe side.
> > 
> > With the current setup (the Kconfig option being a choice which
> > selects one governor at least), it is not possible for gov to be NULL
> > here. And so I didn't worry about it :)
> 
> Right, so should we remove the check in cpufreq_init_policy() then?
> I don't mind either way as long as we are consitent :)

And actually maybe we should remove the weakly defined
cpufreq_default_governor() implementation too? That'd make sure we get a
link-time error if for some reason things change in the Kconfig options.

Thanks,
Quentin