RE: [PATCH] cpufreq: powerpc: replace CPUFREQ_ETERNAL with cpufreq transition latency for FSL e500mc Socs

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> -----Original Message-----
> From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx]
> Sent: Wednesday, March 19, 2014 9:42 AM
> To: Zhang Zhuoyu-B46552
> Cc: viresh.kumar@xxxxxxxxxx; cpufreq@xxxxxxxxxxxxxxx; linux-
> pm@xxxxxxxxxxxxxxx; Tang Yuantian-B29983
> Subject: Re: [PATCH] cpufreq: powerpc: replace CPUFREQ_ETERNAL with
> cpufreq transition latency for FSL e500mc Socs
> 
> On Monday, March 17, 2014 01:29:28 PM Zhuoyu Zhang wrote:
> > According to the data provided by HW Team, at least 12 internal
> > platform clock cycles are required to stabilize a DFS clock switch on
> > FSL e500mc Socs. This patch replaces the CPUFREQ_ETERNAL with
> appropriate HW clock transition latency to make DFS governors work
> normally on Freescale e500mc boards.
> 
> Please sign off the patch.  I can't apply it without your sign-off.

Sorry to miss the "sign-off", I already sent another version for your review.

--Zhuoyu

> 
> > ---
> >  drivers/cpufreq/ppc-corenet-cpufreq.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/cpufreq/ppc-corenet-cpufreq.c
> > b/drivers/cpufreq/ppc-corenet-cpufreq.c
> > index 051000f..ff7b625 100644
> > --- a/drivers/cpufreq/ppc-corenet-cpufreq.c
> > +++ b/drivers/cpufreq/ppc-corenet-cpufreq.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/of.h>
> >  #include <linux/slab.h>
> >  #include <linux/smp.h>
> > +#include <sysdev/fsl_soc.h>
> >
> >  /**
> >   * struct cpu_data - per CPU data struct @@ -205,7 +206,7 @@ static
> > int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
> >  	for_each_cpu(i, per_cpu(cpu_mask, cpu))
> >  		per_cpu(cpu_data, i) = data;
> >
> > -	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
> > +	policy->cpuinfo.transition_latency = (12 * NSEC_PER_SEC) /
> > +fsl_get_sys_freq();
> >  	of_node_put(np);
> >
> >  	return 0;
> >
> 
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
> 

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