Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752502Ab3G3MSM (ORCPT ); Tue, 30 Jul 2013 08:18:12 -0400 Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:18926 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751675Ab3G3MSK (ORCPT ); Tue, 30 Jul 2013 08:18:10 -0400 X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 72.84.113.162 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX18YYl+Ifnn0Q3TgopYfVsgYNkEo3BzBRhA= Date: Tue, 30 Jul 2013 08:17:43 -0400 From: Jason Cooper To: David Gibson Cc: Mark Rutland , Jason Gunthorpe , "ksummit-2013-discuss@lists.linuxfoundation.org" , Russell King - ARM Linux , Ian Campbell , Pawel Moll , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Richard Cochran , Stephen Warren , Wolfram Sang , Tomasz Figa , Grant Likely , "jonsmirl@gmail.com" , Domenico Andreoli , James Bottomley , Dave Martin , "linux-arm-kernel@lists.infradead.org" Subject: Re: [Ksummit-2013-discuss] Defining schemas for Device Tree Message-ID: <20130730121743.GB5882@titan.lakedaemon.net> References: <2469263.vMN09Q7Tzi@flatron> <20130729150124.GS29916@titan.lakedaemon.net> <20130729164905.GB2280@localhost.localdomain> <20130729172339.GT29916@titan.lakedaemon.net> <20130730015031.GK29970@voom.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130730015031.GK29970@voom.fritz.box> 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: 2213 Lines: 47 On Tue, Jul 30, 2013 at 11:50:31AM +1000, David Gibson wrote: > On Mon, Jul 29, 2013 at 01:23:39PM -0400, Jason Cooper wrote: > > On Mon, Jul 29, 2013 at 05:49:05PM +0100, Dave Martin wrote: > > > On Mon, Jul 29, 2013 at 11:01:24AM -0400, Jason Cooper wrote: > > > > On Mon, Jul 29, 2013 at 02:21:52AM +0200, Tomasz Figa wrote: > > > > > > > b) What information should be specified in schemas? What level of > > > > > granularity is required? > > > > > > > > One item I don't see in this list is node ordering. There's been some > > > > discussion lately on deferred probing (re boot times). If we were to > > > > intentionally declare that DT are parsed in the order written, then a > > > > lot of deferred probes could be avoided by moving eg the pinctrl node to > > > > near the top of the tree. > > > > > > > > This doesn't impact buses as much, since the nodes needing the bus are > > > > already children. However, anything accessed via phandles: pins, > > > > clocks, regulators, etc could benefit from declaring and enforcing this. > > > > Eg having the dtc warn when a phandle is used before it's corresponding > > > > node is declared. > > > > > > > > Not critical though, just a thought. > > > > > > I don't think that siblings have any defined order in DT. If reading a > > > device tree, there's no guarantee you get nodes or properties out in the > > > same order as the original .dts file. > > > > That's why I raised the point. If people think encoding initialization > > order in the DT is a good idea, then we should change the dtc so it > > compiles/decompiles in the same order. > > I'm not actually sure what you mean by this. dtc already preserves > order between input and output. This is an old comment (~ 1d, wow). My position has evolved to seeing if we can allow dtc to topsort nodes it can easily tell are needed first as an optimization. *Not* a requirement. Deferred probing would still be a fall back. thx, Jason. -- 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/