From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Tue, 13 Aug 2013 09:48:40 -0600 Subject: =?UTF-8?B?562U5aSNOiBbUEFUQ0ggdjMgMi8yXSBpMmM6IGlteDogQWRkIFY=?= =?UTF-8?B?eWJyaWQgVkY2MTAgSTJDIGNvbnRyb2xsZXIgc3VwcG9ydA==?= In-Reply-To: <20130813074620.GR26614@pengutronix.de> References: <1375418648-22760-1-git-send-email-b35083@freescale.com> <1375418648-22760-2-git-send-email-b35083@freescale.com> <20130810140827.GC18085@e106331-lin.cambridge.arm.com> <20130812164354.GF27165@e106331-lin.cambridge.arm.com> <52096E77.4040003@wwwdotorg.org> <20130813074620.GR26614@pengutronix.de> Message-ID: <520A5558.708@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/13/2013 01:46 AM, s.hauer at pengutronix.de wrote: > On Mon, Aug 12, 2013 at 05:23:35PM -0600, Stephen Warren wrote: >> On 08/12/2013 10:43 AM, Mark Rutland wrote: >>>> The binding string for i2c-imx driver in Documentation/devicetree/bindings/i2c/i2c-imx.txt use a wildcard format >>>> of "- compatible : Should be "fsl,-i2c" " for device using this driver. Neither fsl,imx1-i2c nor fsl,imx21-i2c >>>> is described in the binding document. So I just leave the vf610 i2c compatible with this. >>> >>> I'm not a big fan on wildcards in bindings, as it leaves people free to >>> put anything in and claim it's a documented binding, and makes it far >>> harder for an os to actually implement drivers for said binding, as >>> there's no canonical reference for the set of valid variations. >>> >>> Obviously there is some precedent, but I'm not sure it's something we >>> want to stick with, and we can prevent it my updating the documentation >>> now. >>> >>> Does anyone else have an opinion? >> >> I suppose technically we should list out every exact string in the >> binding, but it's a little annoying to have to update the binding doc >> every time a new chip comes out (and I expect that'll happen more and >> more!) just to add a new compatible value since all the differences are >> known internally to the driver and don't impact the binding... > > We would only have to update the the docs when an incompatible SoC comes > out. For this particular driver this would be all marked with a star: > > * i.MX1 > * i.MX21 > i.MX25 > i.MX27 > i.MX31 > i.MX35 > i.MX51 > i.MX53 > i.MX6 > * Vybrid > > That's not too many updates to the binding docs since 2001. > (The SPI core changed with nearly every SoC version though) So, the SPI core changed its HW implementation, or changed its SW-visible interface? If the latter, then you need a separate compatible value for each, which was my point.