linux-kernel - Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw setting

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Message-ID: <CAJZ5v0imYcL3M80S1snJAqXQ=GsqbChij-6aWx=4L02TKVvrQg@mail.gmail.com>
Date:   Mon, 18 May 2020 12:51:15 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Serge Semin <fancer.lancer@...il.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Stable <stable@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Yue Hu <huyue2@...ong.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw setting

On Mon, May 18, 2020 at 12:46 PM Serge Semin
<Sergey.Semin@...kalelectronics.ru> wrote:
>
> On Mon, May 18, 2020 at 12:41:19PM +0200, Rafael J. Wysocki wrote:
> > On Monday, May 18, 2020 12:31:02 PM CEST Serge Semin wrote:
> > > On Mon, May 18, 2020 at 03:54:15PM +0530, Viresh Kumar wrote:
> > > > On 18-05-20, 12:22, Rafael J. Wysocki wrote:
> > > > > On Monday, May 18, 2020 12:11:09 PM CEST Viresh Kumar wrote:
> > > > > > On 18-05-20, 11:53, Rafael J. Wysocki wrote:
> > > > > > > That said if you really only want it to return 0 on success, you may as well
> > > > > > > add a ret = 0; statement (with a comment explaining why it is needed) after
> > > > > > > the last break in the loop.
> > > > > >
> > > > > > That can be done as well, but will be a bit less efficient as the loop
> > > > > > will execute once for each policy, and so the statement will run
> > > > > > multiple times. Though it isn't going to add any significant latency
> > > > > > in the code.
> > > > >
> > > > > Right.
> > > > >
> > > > > However, the logic in this entire function looks somewhat less than
> > > > > straightforward to me, because it looks like it should return an
> > > > > error on the first policy without a frequency table (having a frequency
> > > > > table depends on the driver and that is the same for all policies, so it
> > > > > is pointless to iterate any further in that case).
> > > > >
> > > > > Also, the error should not be -EINVAL, because that means "invalid
> > > > > argument" which would be the state value.
> > > > >
> > > > > So I would do something like this:
> > > > >
> > > > > ---
> > > > >  drivers/cpufreq/cpufreq.c |   11 ++++++-----
> > > > >  1 file changed, 6 insertions(+), 5 deletions(-)
> > > > >
> > > > > Index: linux-pm/drivers/cpufreq/cpufreq.c
> > > > > ===================================================================
> > > > > --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> > > > > +++ linux-pm/drivers/cpufreq/cpufreq.c
> > > > > @@ -2535,26 +2535,27 @@ EXPORT_SYMBOL_GPL(cpufreq_update_limits)
> > > > >  static int cpufreq_boost_set_sw(int state)
> > > > >  {
> > > > >         struct cpufreq_policy *policy;
> > > > > -       int ret = -EINVAL;
> > > > >
> > > > >         for_each_active_policy(policy) {
> > > > > +               int ret;
> > > > > +
> > > > >                 if (!policy->freq_table)
> > > > > -                       continue;
> > > > > +                       return -ENXIO;
> > > > >
> > > > >                 ret = cpufreq_frequency_table_cpuinfo(policy,
> > > > >                                                       policy->freq_table);
> > > > >                 if (ret) {
> > > > >                         pr_err("%s: Policy frequency update failed\n",
> > > > >                                __func__);
> > > > > -                       break;
> > > > > +                       return ret;
> > > > >                 }
> > > > >
> > > > >                 ret = freq_qos_update_request(policy->max_freq_req, policy->max);
> > > > >                 if (ret < 0)
> > > > > -                       break;
> > > > > +                       return ret;
> > > > >         }
> > > > >
> > > > > -       return ret;
> > > > > +       return 0;
> > > > >  }
> > > > >
> > > > >  int cpufreq_boost_trigger_state(int state)
> > > >
> > > > Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> > >
> > > Ok. Thanks for the comments. Shall I resend the patch with update Rafael
> > > suggests or you'll merge the Rafael's fix in yourself?
> >
> > I'll apply the fix directly, thanks!
>
> Great. Is it going to be available in the repo:
> https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/
> ?

Yes, it is.  Please see the bleeding-edge branch in there, thanks!