linux-kernel - Re: [PATCH 1/1] cpufreq: cpufreq-cpu0: use the max voltage instead of voltage-tolerance

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Date:	Tue, 5 Nov 2013 19:53:09 +0800
From:	Shawn Guo <shawn.guo@...aro.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	rjying <rjying@...il.com>, "Rafael J. Wysocki" <rjw@...k.pl>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	<rongjun.ying@...r.com>, Rongjun Ying <rongjun.ying@....com>
Subject: Re: [PATCH 1/1] cpufreq: cpufreq-cpu0: use the max voltage instead
 of voltage-tolerance

On Tue, Nov 05, 2013 at 10:08:06AM +0530, Viresh Kumar wrote:
> Adding shawn in cc list..
> 
> On 5 November 2013 08:40, rjying <rjying@...il.com> wrote:
> > From: Rongjun Ying <rongjun.ying@....com>
> >
> > Sometime the regulator can't supply appropriate voltages for requestion of cpu.
> > All voltage tolerance value can't figure out a good voltage.

The voltage-tolerance is an optional device tree property.  You can omit
it if you do not have a value for it.

Shawn

> >
> > Signed-off-by: Rongjun Ying <rongjun.ying@....com>
> > ---
> >  drivers/cpufreq/cpufreq-cpu0.c |   17 ++++++++++-------
> >  1 files changed, 10 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
> > index c522a95..0c9e6b9 100644
> > --- a/drivers/cpufreq/cpufreq-cpu0.c
> > +++ b/drivers/cpufreq/cpufreq-cpu0.c
> > @@ -23,7 +23,7 @@
> >  #include <linux/slab.h>
> >
> >  static unsigned int transition_latency;
> > -static unsigned int voltage_tolerance; /* in percentage */
> > +static unsigned int voltage_max;
> >
> >  static struct device *cpu_dev;
> >  static struct clk *cpu_clk;
> > @@ -45,7 +45,7 @@ static int cpu0_set_target(struct cpufreq_policy *policy,
> >  {
> >         struct cpufreq_freqs freqs;
> >         struct opp *opp;
> > -       unsigned long volt = 0, volt_old = 0, tol = 0;
> > +       unsigned long volt = 0, volt_old = 0;
> >         long freq_Hz, freq_exact;
> >         unsigned int index;
> >         int ret;
> > @@ -82,7 +82,6 @@ static int cpu0_set_target(struct cpufreq_policy *policy,
> >                 }
> >                 volt = opp_get_voltage(opp);
> >                 rcu_read_unlock();
> > -               tol = volt * voltage_tolerance / 100;
> >                 volt_old = regulator_get_voltage(cpu_reg);
> >         }
> >
> > @@ -92,7 +91,7 @@ static int cpu0_set_target(struct cpufreq_policy *policy,
> >
> >         /* scaling up?  scale voltage before frequency */
> >         if (!IS_ERR(cpu_reg) && freqs.new > freqs.old) {
> > -               ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
> > +               ret = regulator_set_voltage(cpu_reg, volt, voltage_max);
> >                 if (ret) {
> >                         pr_err("failed to scale voltage up: %d\n", ret);
> >                         freqs.new = freqs.old;
> > @@ -104,14 +103,14 @@ static int cpu0_set_target(struct cpufreq_policy *policy,
> >         if (ret) {
> >                 pr_err("failed to set clock rate: %d\n", ret);
> >                 if (!IS_ERR(cpu_reg))
> > -                       regulator_set_voltage_tol(cpu_reg, volt_old, tol);
> > +                       regulator_set_voltage(cpu_reg, volt_old, voltage_max);
> >                 freqs.new = freqs.old;
> >                 goto post_notify;
> >         }
> >
> >         /* scaling down?  scale voltage after frequency */
> >         if (!IS_ERR(cpu_reg) && freqs.new < freqs.old) {
> > -               ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
> > +               ret = regulator_set_voltage(cpu_reg, volt, voltage_max);
> >                 if (ret) {
> >                         pr_err("failed to scale voltage down: %d\n", ret);
> >                         clk_set_rate(cpu_clk, freqs.old * 1000);
> > @@ -224,7 +223,11 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
> >                 goto out_put_node;
> >         }
> >
> > -       of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
> > +       ret = of_property_read_u32(np, "voltage-max", &voltage_max);
> > +       if (ret) {
> > +               pr_err("failed to get max voltage: %d\n", ret);
> > +               goto out_put_node;
> > +       }
> >
> >         if (of_property_read_u32(np, "clock-latency", &transition_latency))
> >                 transition_latency = CPUFREQ_ETERNAL;
> > --
> > 1.7.5.4
> >

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