From: Quentin Perret <qperret@google.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Arnd Bergmann <arnd@arndb.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
"Cc: Android Kernel" <kernel-team@android.com>,
Todd Kjos <tkjos@google.com>,
adharmap@codeaurora.org
Subject: Re: [PATCH v2 2/2] cpufreq: Specify default governor on command line
Date: Thu, 25 Jun 2020 14:49:53 +0100 [thread overview]
Message-ID: <20200625134953.GA242742@google.com> (raw)
In-Reply-To: <CAJZ5v0jQkeu5dJXxXN2eQ+cAwv8oSK_wZZgTW3cvMZX0ks9jHQ@mail.gmail.com>
On Thursday 25 Jun 2020 at 15:28:43 (+0200), Rafael J. Wysocki wrote:
> On Thu, Jun 25, 2020 at 1:53 PM Quentin Perret <qperret@google.com> wrote:
> >
> > On Thursday 25 Jun 2020 at 13:44:34 (+0200), Rafael J. Wysocki wrote:
> > > On Thu, Jun 25, 2020 at 1:36 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > > > This change is not right IMO. This part handles the set-policy case,
> > > > where there are no governors. Right now this code, for some reasons
> > > > unknown to me, forcefully uses the default governor set to indicate
> > > > the policy, which is not a great idea in my opinion TBH. This doesn't
> > > > and shouldn't care about governor modules and should only be looking
> > > > at strings instead of governor pointer.
> > >
> > > Sounds right.
> > >
> > > > Rafael, I even think we should remove this code completely and just
> > > > rely on what the driver has sent to us. Using the selected governor
> > > > for set policy drivers is very confusing and also we shouldn't be
> > > > forced to compiling any governor for the set-policy case.
> > >
> > > Well, AFAICS the idea was to use the default governor as a kind of
> > > default policy proxy, but I agree that strings should be sufficient
> > > for that.
> >
> > I agree with all the above. I'd much rather not rely on the default
> > governor name to populate the default policy, too, so +1 from me.
>
> So before this series the default governor was selected at the kernel
> configuration time (pre-build) and was always built-in. Because it
> could not go away, its name could be used to indicate the default
> policy for the "setpolicy" drivers.
>
> After this series, however, it cannot be used this way reliably, but
> you can still pass cpufreq_param_governor to cpufreq_parse_policy()
> instead of def_gov->name in cpufreq_init_policy(), can't you?
Good point. I also need to fallback to the default builtin governor if
the command line parameter isn't valid (or non-existent), so perhaps
something like so?
iff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index dad6b85f4c89..20a2020abf88 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -653,6 +653,23 @@ static unsigned int cpufreq_parse_policy(char *str_governor)
return CPUFREQ_POLICY_UNKNOWN;
}
+static unsigned int cpufreq_default_policy(void)
+{
+ unsigned int pol;
+
+ pol = cpufreq_parse_policy(cpufreq_param_governor);
+ if (pol != CPUFREQ_POLICY_UNKNOWN)
+ return pol;
+
+ if (IS_BUILTIN(CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE))
+ return CPUFREQ_POLICY_PERFORMANCE;
+
+ if (IS_BUILTIN(CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE))
+ return CPUFREQ_POLICY_POWERSAVE;
+
+ return CPUFREQ_POLICY_UNKNOWN;
+}
+
/**
* cpufreq_parse_governor - parse a governor string only for has_target()
* @str_governor: Governor name.
@@ -1085,8 +1102,8 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy)
/* Use the default policy if there is no last_policy. */
if (policy->last_policy) {
pol = policy->last_policy;
- } else if (default_governor) {
- pol = cpufreq_parse_policy(default_governor->name);
+ } else {
+ pol = cpufreq_default_policy();
/*
* In case the default governor is neiter "performance"
* nor "powersave", fall back to the initial policy
next prev parent reply other threads:[~2020-06-25 13:50 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 14:21 [PATCH v2 0/2] cpufreq: Specify the default governor on command line Quentin Perret
2020-06-23 14:21 ` [PATCH v2 1/2] cpufreq: Register governors at core_initcall Quentin Perret
2020-06-23 14:21 ` [PATCH v2 2/2] cpufreq: Specify default governor on command line Quentin Perret
2020-06-24 5:50 ` Viresh Kumar
2020-06-24 12:51 ` Rafael J. Wysocki
2020-06-24 15:32 ` Quentin Perret
2020-06-25 8:50 ` Viresh Kumar
2020-06-25 10:52 ` Rafael J. Wysocki
2020-06-25 11:36 ` Viresh Kumar
2020-06-25 11:44 ` Rafael J. Wysocki
2020-06-25 11:53 ` Quentin Perret
2020-06-25 13:28 ` Rafael J. Wysocki
2020-06-25 13:49 ` Quentin Perret [this message]
2020-06-25 14:08 ` Rafael J. Wysocki
2020-06-26 2:53 ` Viresh Kumar
2020-06-26 8:09 ` Quentin Perret
2020-06-23 17:54 ` [PATCH v2 0/2] cpufreq: Specify the " Doug Smythies
2020-06-23 18:04 ` Quentin Perret
2020-06-24 0:07 ` Doug Smythies
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