Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964820Ab2KEXWb (ORCPT ); Mon, 5 Nov 2012 18:22:31 -0500 Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:25651 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754326Ab2KEXW1 (ORCPT ); Mon, 5 Nov 2012 18:22:27 -0500 X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 98.234.237.12 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX1/x7nAouzc0Knr7ydG3ZB/Y Date: Mon, 5 Nov 2012 15:22:19 -0800 From: Tony Lindgren To: Tabi Timur-B04825 Cc: Grant Likely , Pantelis Antoniou , Rob Herring , Deepak Saxena , Benjamin Herrenschmidt , Wood Scott-B07421 , Kevin Hilman , Matt Porter , Koen Kooi , linux-kernel , Felipe Balbi , Russ Dill , "linux-omap@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" Subject: Re: [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2) Message-ID: <20121105232218.GA8284@atomide.com> References: <6AE080B68D46FC4BA2D2769E68D765B708174B7D@039-SN2MPN1-023.039d.mgd.msft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6AE080B68D46FC4BA2D2769E68D765B708174B7D@039-SN2MPN1-023.039d.mgd.msft.net> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1347 Lines: 32 Hi, * Tabi Timur-B04825 [121105 13:42]: > On Mon, Nov 5, 2012 at 2:40 PM, Grant Likely wrote: > > > Jane is building custom BeagleBone expansion boards called 'capes'. She > > can boot the system with a stock BeagleBoard device tree, but additional > > data is needed before a cape can be used. She could replace the FDT file > > used by U-Boot with one that contains the extra data, but she uses the > > same Linux system image regardless of the cape, and it is inconvenient > > to have to select a different device tree at boot time depending on the > > cape. > > What's wrong with having the boot loader detect the presence of the > Cape and update the device tree accordingly? We do this all the time > in U-Boot. Doing stuff like reading EEPROMs and testing for the > presence of hardware is easier in U-Boot than in Linux. > > For configurations that can be determined by the boot loader, I'm not > sure overlays are practical. I guess the beaglebone capes could be stackable and hotpluggable if handled carefully enough. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/