From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukas Wunner Subject: Re: [PATCH 3/4] dt-bindings: gpio: max3191x: Document new driver Date: Wed, 4 Oct 2017 21:31:53 +0200 Message-ID: <20171004193153.GA9195@wunner.de> References: <7fe7636eecba238d57ab6178cfa3f6b7deca98f1.1503319573.git.lukas@wunner.de> <20170823004847.jmkb53xtdmmn6vtf@rob-hp-laptop> <20170905081624.GA15374@wunner.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170905081624.GA15374@wunner.de> Sender: linux-gpio-owner@vger.kernel.org To: Rob Herring Cc: Linus Walleij , Mathias Duckeck , Phil Elwell , linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, Mark Rutland List-Id: devicetree@vger.kernel.org Hi Rob, gentle ping on this question: On Tue, Sep 05, 2017 at 10:16:24AM +0200, Lukas Wunner wrote: > 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