[2/3] cpufreq: pmac64: re-estimate G5 cpufreq transition latency

The latency is in milliseconds scale rather than microseconds based on
measurements on iMac G5 and Xscale G5. The patch also enables to use
ondemand governor on the latter.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
---
 drivers/cpufreq/pmac64-cpufreq.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

On 24 July 2013 01:54, Aaro Koskinen <aaro.koskinen@iki.fi> wrote:
> The patch also enables to use ondemand governor on the latter.

How? I can't see anything obvious here. :(

>
> Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
> ---
>  drivers/cpufreq/pmac64-cpufreq.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/pmac64-cpufreq.c b/drivers/cpufreq/pmac64-cpufreq.c
> index 674807d..f9e399b 100644
> --- a/drivers/cpufreq/pmac64-cpufreq.c
> +++ b/drivers/cpufreq/pmac64-cpufreq.c
> @@ -85,7 +85,8 @@ static int (*g5_query_freq)(void);
>
>  static DEFINE_MUTEX(g5_switch_mutex);
>
> -static unsigned long transition_latency;
> +/* A conservative estimate, based on Xserve G5 and iMac G5 (iSight). */
> +static const unsigned long transition_latency = 10 * NSEC_PER_MSEC;
>
>  #ifdef CONFIG_PMAC_SMU
>
> @@ -499,7 +500,6 @@ static int __init g5_neo2_cpufreq_init(struct device_node *cpus)
>         g5_cpu_freqs[1].frequency = max_freq/2;
>
>         /* Set callbacks */
> -       transition_latency = 12000;
>         g5_switch_freq = g5_scom_switch_freq;
>         g5_query_freq = g5_scom_query_freq;
>         freq_method = "SCOM";
> @@ -675,7 +675,6 @@ static int __init g5_pm72_cpufreq_init(struct device_node *cpus)
>         g5_cpu_freqs[1].frequency = min_freq;
>
>         /* Set callbacks */
> -       transition_latency = CPUFREQ_ETERNAL;
>         g5_switch_volt = g5_pfunc_switch_volt;
>         g5_switch_freq = g5_pfunc_switch_freq;
>         g5_query_freq = g5_pfunc_query_freq;
> --
> 1.8.3.2
>

Hi,

On Wed, Jul 24, 2013 at 11:04:50AM +0530, Viresh Kumar wrote:
> On 24 July 2013 01:54, Aaro Koskinen <aaro.koskinen@iki.fi> wrote:
> > The patch also enables to use ondemand governor on the latter.
> 
> How? I can't see anything obvious here. :(

It replaces CPUFREQ_ETERNAL with a proper value on older PowerMacs.
ondemand does not accept CPUFREQ_ETERNAL transition latency.

A.

> 
> >
> > Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
> > ---
> >  drivers/cpufreq/pmac64-cpufreq.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/cpufreq/pmac64-cpufreq.c b/drivers/cpufreq/pmac64-cpufreq.c
> > index 674807d..f9e399b 100644
> > --- a/drivers/cpufreq/pmac64-cpufreq.c
> > +++ b/drivers/cpufreq/pmac64-cpufreq.c
> > @@ -85,7 +85,8 @@ static int (*g5_query_freq)(void);
> >
> >  static DEFINE_MUTEX(g5_switch_mutex);
> >
> > -static unsigned long transition_latency;
> > +/* A conservative estimate, based on Xserve G5 and iMac G5 (iSight). */
> > +static const unsigned long transition_latency = 10 * NSEC_PER_MSEC;
> >
> >  #ifdef CONFIG_PMAC_SMU
> >
> > @@ -499,7 +500,6 @@ static int __init g5_neo2_cpufreq_init(struct device_node *cpus)
> >         g5_cpu_freqs[1].frequency = max_freq/2;
> >
> >         /* Set callbacks */
> > -       transition_latency = 12000;
> >         g5_switch_freq = g5_scom_switch_freq;
> >         g5_query_freq = g5_scom_query_freq;
> >         freq_method = "SCOM";
> > @@ -675,7 +675,6 @@ static int __init g5_pm72_cpufreq_init(struct device_node *cpus)
> >         g5_cpu_freqs[1].frequency = min_freq;
> >
> >         /* Set callbacks */
> > -       transition_latency = CPUFREQ_ETERNAL;
> >         g5_switch_volt = g5_pfunc_switch_volt;
> >         g5_switch_freq = g5_pfunc_switch_freq;
> >         g5_query_freq = g5_pfunc_query_freq;
> > --
> > 1.8.3.2
> >

On 24 July 2013 15:48, Aaro Koskinen <aaro.koskinen@iki.fi> wrote:
> Hi,
>
> On Wed, Jul 24, 2013 at 11:04:50AM +0530, Viresh Kumar wrote:
>> On 24 July 2013 01:54, Aaro Koskinen <aaro.koskinen@iki.fi> wrote:
>> > The patch also enables to use ondemand governor on the latter.
>>
>> How? I can't see anything obvious here. :(
>
> It replaces CPUFREQ_ETERNAL with a proper value on older PowerMacs.
> ondemand does not accept CPUFREQ_ETERNAL transition latency.

Ahh.. In case you are sending it again, just add this info in log as people
might miss it.