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

[Lukas Wunner <lukas@xxxxxxxxx>]

Hi Rob,

sorry to bother you again, one more question popped up regarding the
MAX3191x DT bindings:

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:
> > Add device tree bindings for Maxim MAX3191x industrial serializer.
[snip]
> > +Optional properties:
> > + - maxim,nchips:	Number of chips in the daisy-chain (default is 1).

Many I/O chips are daisy-chainable, so I've been wondering if a
common property should be introduced?

The existing gpio-74x164.c uses "registers-number" to convey the number
of chips in the daisy chain.  (Sans vendor prefix, multiple vendors sell
compatible versions of this chip.)

gpio-pisosr.c takes a different approach and calculates the number of
chips in the daisy-chain by taking the common "ngpios" property
(Documentation/devicetree/bindings/gpio/gpio.txt) and dividing it by 8
(which assumes that each chip has 8 inputs).

Thanks,

Lukas
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