2015-07-28 09:02:24

by Timo Sigurdsson

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Subject: Re: [linux-sunxi] [RFC] ARM: dts: sunxi: Add regulators and board-specific operating points for LeMaker BananaPi

Hi,

Chen-Yu Tsai schrieb am 27.07.2015 15:14:
>> ChenYu (in the CC), since you did most of the original work here, do
>> you know why we have an op at 0.9 volt, but none of our boards allow the
>> voltage to go that low in the regulator settings ?
>
> I'm on vacation now, so apologies for the bad formatting.
>
> The OPPs are from a common subset
> of the settings from the fex files available
> at the time. Some fex files actually set
> min and max voltage thus eliminating
> the highest and lowest OPPs.
>
> At least that is how Maxime and I
> interpreted them.

IMHO for a common maximum opp that's a good approach. But for the lowest
frequency setting, it would seem more logical to me, to raise the voltage
to a point where all boards will run fine with them, unless those boards
cannot handle the frequency regardless of the higher voltage.

Regards,

Timo


2015-07-28 12:56:08

by Maxime Ripard

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Subject: Re: [linux-sunxi] [RFC] ARM: dts: sunxi: Add regulators and board-specific operating points for LeMaker BananaPi

On Tue, Jul 28, 2015 at 11:02:16AM +0200, Timo Sigurdsson wrote:
> Hi,
>
> Chen-Yu Tsai schrieb am 27.07.2015 15:14:
> >> ChenYu (in the CC), since you did most of the original work here, do
> >> you know why we have an op at 0.9 volt, but none of our boards allow the
> >> voltage to go that low in the regulator settings ?
> >
> > I'm on vacation now, so apologies for the bad formatting.
> >
> > The OPPs are from a common subset
> > of the settings from the fex files available
> > at the time. Some fex files actually set
> > min and max voltage thus eliminating
> > the highest and lowest OPPs.
> >
> > At least that is how Maxime and I
> > interpreted them.
>
> IMHO for a common maximum opp that's a good approach. But for the lowest
> frequency setting, it would seem more logical to me, to raise the voltage
> to a point where all boards will run fine with them, unless those boards
> cannot handle the frequency regardless of the higher voltage.

Agreed.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com


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2015-07-28 15:01:29

by Timo Sigurdsson

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Subject: Re: [linux-sunxi] [RFC] ARM: dts: sunxi: Add regulators and board-specific operating points for LeMaker BananaPi

Hi,

Maxime Ripard schrieb am 28.07.2015 14:55:
>> IMHO for a common maximum opp that's a good approach. But for the lowest
>> frequency setting, it would seem more logical to me, to raise the voltage
>> to a point where all boards will run fine with them, unless those boards
>> cannot handle the frequency regardless of the higher voltage.
>
> Agreed.

Ok, then I will write another patch for this as well, unless Chen-Yu or
someone else objects.

Regards,

Timo