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

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Date:	Thu, 3 Apr 2014 09:51:41 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Aaro Koskinen <aaro.koskinen@....fi>
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

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..

>         int ret = 0;
>         int regval;
>         int i;
> @@ -106,15 +107,17 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
>         if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
>                 propagate_rate(clk);
>
> +       rate_khz = rate / 1000;
> +

>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().
--
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