[linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

Maxime Ripard
2016-01-04T10:11:21Z

Hi,

On Tue, Dec 22, 2015 at 12:29:24PM +0800, Chen-Yu Tsai wrote:
> >>> So this means enabled the sdio controller (should be safe on all
> >>> boards?) and enabling 2 regulators to power the wifi-chip. I
> >>> think it will be safe to do this even on boards where those
> >>> regulators are not used, what do you think ?
> >>
> >> Wouldn't that introduce some useless power drain on those boards?
> >
> >
> > If nothing is attached to those regulators (which I expect to be
> > the case when they are not used to power wifi) then I would expect
> > the drain to be minimal, my biggest worry is some board having
> > tied these to ground, but I don't think that is very likely.
>
> AFAIK the AXP datasheets mention that unused DCDC outputs should be left
> floating. Not sure if this applies to LDO outputs as well. But any used
> outputs would have a bypass capacitor.
>
> From the board designs I've seen, this seems to be the common case.
> I'm not an electrical engineer, but I think we're covered here.

Ok, I guess we're good then.

Thanks!
Maxime

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