linux-kernel - Re: [PATCH] MIPS/loongson2_cpufreq: fix CPU clock rate setting

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Message-ID: <20140403183053.GA9247@drone.musicnaut.iki.fi>
Date:	Thu, 3 Apr 2014 21:30:54 +0300
From:	Aaro Koskinen <aaro.koskinen@....fi>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Ralf Baechle <ralf@...ux-mips.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-mips@...ux-mips.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH] MIPS/loongson2_cpufreq: fix CPU clock rate setting

Hi,

On Thu, Apr 03, 2014 at 09:51:41AM +0530, Viresh Kumar wrote:
> On 3 April 2014 00:37, Aaro Koskinen <aaro.koskinen@....fi> wrote:
> > Loongson2 has been using (incorrectly) kHz for cpu_clk rate. This has
> > been unnoticed, as loongson2_cpufreq was the only place where the rate
> > was set/get. After commit 652ed95d5fa6074b3c4ea245deb0691f1acb6656
> > (cpufreq: introduce cpufreq_generic_get() routine) things however broke,
> > and now loops_per_jiffy adjustments are incorrect (1000 times too long).
> > The patch fixes this by changing cpu_clk rate to Hz.
> >
> > Signed-off-by: Aaro Koskinen <aaro.koskinen@....fi>
> > Cc: stable@...r.kernel.org
> > ---
> >  arch/mips/loongson/lemote-2f/clock.c | 7 +++++--
> >  drivers/cpufreq/loongson2_cpufreq.c  | 4 ++--
> >  2 files changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/mips/loongson/lemote-2f/clock.c b/arch/mips/loongson/lemote-2f/clock.c
> > index aed32b8..699f388 100644
> > --- a/arch/mips/loongson/lemote-2f/clock.c
> > +++ b/arch/mips/loongson/lemote-2f/clock.c
> > @@ -91,6 +91,7 @@ EXPORT_SYMBOL(clk_put);
> >
> >  int clk_set_rate(struct clk *clk, unsigned long rate)
> >  {
> > +       unsigned int rate_khz;
> 
> Initialize rate_khz here only instead of doing it separately..

Ok.

> From here:
> 
> >         for (i = 0; loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END;
> >              i++) {
> >                 if (loongson2_clockmod_table[i].frequency ==
> >                     CPUFREQ_ENTRY_INVALID)
> >                         continue;
> > -               if (rate == loongson2_clockmod_table[i].frequency)
> > +               if (rate_khz == loongson2_clockmod_table[i].frequency)
> >                         break;
> >         }
> > -       if (rate != loongson2_clockmod_table[i].frequency)
> > +       if (rate_khz != loongson2_clockmod_table[i].frequency)
> >                 return -ENOTSUPP;
> 
> To here:
> 
> All this code is junk and not required anymore as rate is guaranteed
> to be in loongson2_clockmod_table[].. Probably you need value of
> 'i' here and you can pass that directly from loongson2_cpufreq_target().

But then we couldn't use clk_set_rate()? Anyway I think that should
be done with separate patch(es), which probably would not qualify
for 3.14-stable or 3.15-rc.

A.
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