Re: [PATCH 3/4] dt-bindings: gpio: max3191x: Document new driver

[Lukas Wunner <lukas@xxxxxxxxx>]

Thanks Rob for the helpful review!

On Tue, Aug 22, 2017 at 07:48:47PM -0500, Rob Herring wrote:
> On Mon, Aug 21, 2017 at 03:12:00PM +0200, Lukas Wunner wrote:
> > + - modesel-gpios:	GPIO pins to configure modesel of each chip.
> > +			The number of GPIOs must be equal to "maxim,nchips".
> > + - fault-gpios: 	GPIO pins to read undervoltage fault of each chip.
> > + - db0-gpios:	GPIO pins to configure debounce of each chip.
> > + - db1-gpios:	GPIO pins to configure debounce of each chip.
> 
> Perhaps an array db-gpios with 2 entries.

Each of the db0-gpios and db1-gpios is already an array with one pin for
each chip in the daisy-chain.

So it would have to be a two-dimensional array, which AFAICS is not
supported by the devicetree spec, or is it?

However I realize that for clarity I should amend fault-gpios, db0-gpios
and db1-gpios with the same text as modesel-gpios:
			The number of GPIOs must be equal to "maxim,nchips".


> > + - maxim,no-vcc24v:Boolean, whether the chips are powered through
> > +			5VOUT instead of VCC24V.
> 
> Use the regulator binding here?

I'd have to look at the regulator's current voltage to determine through
which pin the chips in the daisy-chain are powered (5VOUT or VCC24V).

But if the regulator is generating 5V I couldn't discern if it's a
faulting 24V supply or a non-faulting 5V supply.

So a boolean does seem necessary, however I realize now that "no-vcc24v"
is misleading, I've changed it to "maxim,ignore-undervoltage" for clarity:

- maxim,ignore-undervoltage:
			Boolean, whether to ignore undervoltage alarms signaled
			by the "maxim,fault-gpios" and by the status byte
			(in 16-bit mode).  Use this if the chips are powered
			through 5VOUT instead of VCC24V, in which case they
			will constantly signal undervoltage.

Thanks,

Lukas
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