From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from saturn.retrosnub.co.uk ([178.18.118.26]:38246 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753271AbbHVSJ2 (ORCPT ); Sat, 22 Aug 2015 14:09:28 -0400 Subject: Re: [PATCH 13/18] iio: adc: mcp320x: Set struct spi_driver .of_match_table To: Michael Welling , Javier Martinez Canillas References: <1440054451-1223-1-git-send-email-javier@osg.samsung.com> <1440054451-1223-14-git-send-email-javier@osg.samsung.com> <20150820200912.GA2866@deathstar> <55D64E80.4050502@osg.samsung.com> <20150820222906.GB28249@deathstar> <55D65937.6070909@osg.samsung.com> <20150820235340.GA31967@deathstar> Cc: linux-kernel@vger.kernel.org, Andrea Galbusera , linux-iio@vger.kernel.org, Peter Meerwald , Lars-Peter Clausen , Manfred Schlaegl , =?UTF-8?Q?S=c3=b8ren_Andersen?= , Hartmut Knaack From: Jonathan Cameron Message-ID: <55D8BAD5.4020501@kernel.org> Date: Sat, 22 Aug 2015 19:09:25 +0100 MIME-Version: 1.0 In-Reply-To: <20150820235340.GA31967@deathstar> Content-Type: text/plain; charset=windows-1252 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 21/08/15 00:53, Michael Welling wrote: > On Fri, Aug 21, 2015 at 12:48:23AM +0200, Javier Martinez Canillas wrote: >> Hello Michael, >> >> On 08/21/2015 12:29 AM, Michael Welling wrote: >>> On Fri, Aug 21, 2015 at 12:02:40AM +0200, Javier Martinez Canillas wrote: >>>> Hello Michael, >>>> >>>> On 08/20/2015 10:09 PM, Michael Welling wrote: >>>>> On Thu, Aug 20, 2015 at 09:07:26AM +0200, Javier Martinez Canillas wrote: >>>>>> The driver has an OF id table but the .of_match_table is not set so >>>>>> the SPI core can't do an OF style match and the table was unused. >>>>>> >>>>> >>>>> Is an OF style match necessary? >>>>> >>>> >>>> Did you read the cover letter [0] on which I explain why is needed to >>>> avoid breaking module autoloading in the future? Once the SPI core is >>>> changed by RFC patch 18/18? (you were cc'ed in the cover letter BTW). >>> >>> Well I have read it now. :) >>> >> >> Great :) >> >>>> >>>>> I have been using devicetree and it matches based on the .id_table. >>>>> >>>> >>>> Yes it fallbacks to the .id_table or the driver name but the correct >>>> thing to do for devices registered by OF, is to match using the >>>> compatible string. >>>> >>>>> Couldn't we just remove the mcp320x_dt_ids table instead? >>>>> >>>> >>>> No, that is the wrong thing to do IMHO since the compatible string >>>> contains both vendor and device name whle the .id_table only contains >>>> a device name. >>>> >>>> So it makes sense to match using the compatible string and also report >>>> the OF modalias information to user-space. >>>> >>>> Otherwise what's the point of the vendor in the compatible string for >>>> SPI devices? You can just use "bar" instead of "foo,bar" as a string. >>>> >>> >>> Well then shouldn't the patch include adding the vendor to the compatible >>> string? >>> >> >> Well, I was talking in general. You are right that this specific driver does >> not have a vendor prefix for the compatible strings. This is incorrect >> according to the ePAPR document [0]. >> >> However, these compatible strings are already documented as a DT binding doc >> in Documentation/devicetree/bindings/iio/adc/mcp320x.txt so I don't know >> what is the correct thing to do in this situation. >> >> Changing the compatible string will break old DTB with newer kernels and that >> is a no go. But that doesn't invalidate what I said since once the SPI core >> is changed and report OF modalias, you will need a MODULE_DEVICE_TABLE(of,...) >> regardless if the compatible string has a vendor prefix or not. >> > > Okay. > > Acked-by: Michael Welling Applied to the togreg branch of iio.git Thanks, Jonathan > >> [0]: https://www.power.org/documentation/epapr-version-1-1/ >> >> Best regards, >> -- >> Javier Martinez Canillas >> Open Source Group >> Samsung Research America > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >