From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Cousson, Benoit" Subject: Re: [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2) Date: Thu, 8 Nov 2012 11:36:54 +0100 Message-ID: <509B8B46.8040703@ti.com> References: <02FF5400-9F97-4B8A-AEF0-267B01C8099F@antoniou-consulting.com> <5ED17D42-07B8-4D4F-B54F-82B4CC60584C@antoniou-consulting.com> <509A3595.7050600@ti.com> <509A9984.3000709@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <509A9984.3000709@wwwdotorg.org> Sender: linux-omap-owner@vger.kernel.org To: Stephen Warren Cc: Pantelis Antoniou , Kevin Hilman , Matt Porter , Koen Kooi , linux-kernel , Felipe Balbi , Deepak Saxena , Scott Wood , Russ Dill , linux-omap@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, Peter Ujfalusi List-Id: devicetree@vger.kernel.org + Peter Hi Stephen, On 11/7/2012 6:25 PM, Stephen Warren wrote: > On 11/07/2012 03:19 AM, Benoit Cousson wrote: >> Hi Panto, >> >> On 11/07/2012 09:13 AM, Pantelis Antoniou wrote: >>> Hi Grant >>> >>> On Nov 6, 2012, at 9:45 PM, Grant Likely wrote: >>> >>>> On Tue, Nov 6, 2012 at 7:34 PM, Pantelis Antoniou >>>> wrote: >>> >>> [ snip ] >>>> >>>> g. >>> >>> Since we've started talking about longer term goals, and the versioning >>> provision seems to stand, I hope we address how much the fragment versioning >>> thing is similar to the way board revisions progress. >>> >>> If a versioning syntax is available then one could create a single DT >>> file for a bunch of 'almost' similar board and board revisions. >> >> I even think that the version issue is probably much more important for the short term than the overlay aspect. Well at least as important. We start having as well a bunch a panda board version with different HW setup. >> >> Having a single board-XXX.dts that will support all these versions is probably the best approach to avoid choosing that from the bootloader. >> >> We need to figure out a format + mechanism compatible with the current non-versioned format to allow filtering the nodes at runtime to keep only the relevant one. >> >> Something that can find the driver that will provide the proper board version or subsystem version or whatever like that: >> >> compatible-version = "ti,panda-version", "panda"; >> >> Then at runtime we should create only the node with the correct match between the driver version and the string version. >> >> >> /* regular panda audio routing */ >> sound: sound { >> compatible = "ti,abe-twl6040"; >> ti,model = "PandaBoard"; >> compatible-version = "ti,panda-version", "panda"; >> >> /* Audio routing */ >> ti,audio-routing = >> "Headset Stereophone", "HSOL", >> "Headset Stereophone", "HSOR", >> "Ext Spk", "HFL", >> "Ext Spk", "HFR", >> "Line Out", "AUXL", >> "Line Out", "AUXR", >> "HSMIC", "Headset Mic", >> "Headset Mic", "Headset Mic Bias", >> "AFML", "Line In", >> "AFMR", "Line In"; >> }; >> >> >> /* Audio routing is different between PandaBoard4430 and PandaBoardES */ >> &sound { >> ti,model = "PandaBoardES"; >> compatible-version = "ti,panda-version", "panda-es"; >> >> /* Audio routing */ >> ti,audio-routing = >> "Headset Stereophone", "HSOL", >> "Headset Stereophone", "HSOR", >> "Ext Spk", "HFL", >> "Ext Spk", "HFR", >> "Line Out", "AUXL", >> "Line Out", "AUXR", >> "AFML", "Line In", >> "AFMR", "Line In"; >> }; >> >> >> Maybe some extra version match table can just be passed during the board machine_init >> >> of_platform_populate(NULL, omap_dt_match_table, NULL, NULL, panda_version_match_table); > > Is the only difference here the content of the ti,audio-routing > property? If so, then I don't think there's any need for infra-structure > for this; the driver code already reads that property and adjusts its > behaviour based upon it. That was just an example, and maybe not the best one. It could be any kind of HW differences, like a different GPIO line, a different I2C peripheral, an extra DCDC... The point was just that you might have several version of the same node with different attributes depending of the board revision. Regards, Benoit