Re: VDD1 voltage after resume from idle

[Jean Pihet <jpihet@mvista.com>]

Hi Kevin,

On Friday 20 November 2009 19:29:02 Kevin Hilman wrote:
> Maxime Petazzoni <mpetazzoni@mvista.com> writes:
> > Hi,
> >
> > * Premi, Sanjeev <premi@ti.com> [2009-11-20 21:17:04]:
> >> I am facing a strange problem on OMAP3EVM after resuming from idle.
> >> When using OPP5, the VDD1 voltage ramps to 1.35V.
> >>
> >> However, when i go thru the idle/wakeup cycle, the voltage never
> >> ramps back to 1.35V but stays at 1.20V.
> >
> > I'm seeing some interesting behavior with the OPP values here, too, with
> > suspend/resume. I'm using SRF based PM and CPUFREQ. Here's what happens:
> >
> > When changing the CPU frequency through the scaling_setfreq knob of
> > CPUFREQ, the vdd{1,2}_opp values are updated accordingly. After a
> > suspend/resume cycles, the OPPs return to their pre-suspend values, all
> > is fine.
> >
> > But when changing the OPP values by hand through the vdd{1,2}_opp knobs,
> > the CPU frequency is changed accordingly, which is expected. But after a
> > suspend/resume cycle, the OPP values return to the value CPUFREQ set
> > them to (which may be different than the default OPP values of 3).
> >
> > Is this the normal behavior? Is cpufreq authoritative on the OPP values
> > on resume? Or should it follow whatever value was manually set before
> > suspending?
>
> FWIW, the vdd*_opp sysfs hooks were for initial debug/dev and should
> be considered experimental (a.k.a broken.) They will disappear from
> the PM branch shortly.
>
> CPUfreq should be the only interface used for DVFS.
Could the PM page on elinux.org be updated with that info? I am proposing to 
change it before you ask me ;p

>
> Kevin

Thanks,
Jean

> --
> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html