Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757339Ab0F3VxO (ORCPT ); Wed, 30 Jun 2010 17:53:14 -0400 Received: from mail-gw0-f46.google.com ([74.125.83.46]:33271 "EHLO mail-gw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756811Ab0F3VxM convert rfc822-to-8bit (ORCPT ); Wed, 30 Jun 2010 17:53:12 -0400 MIME-Version: 1.0 In-Reply-To: <20100629193618.5a840b8e@dev.queued.net> References: <20100628215407.2017bf2f@debian> <20100628220037.5744c207@debian> <20100629110324.2756cc02@debian> <20100629193618.5a840b8e@dev.queued.net> From: Grant Likely Date: Wed, 30 Jun 2010 15:52:51 -0600 X-Google-Sender-Auth: ZLv8u8fzN85G2CzLPtQBWejzmx8 Message-ID: Subject: Re: [PATCH 2/4] sparc: break out some prom device-tree building code out into drivers/of To: Andres Salomon Cc: devicetree-discuss@lists.ozlabs.org, sparclinux@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, cjb@laptop.org, Mitch Bradley , pgf@laptop.org, linux-kernel@vger.kernel.org, davem@davemloft.net, Benjamin Herrenschmidt Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2003 Lines: 55 On Tue, Jun 29, 2010 at 5:36 PM, Andres Salomon wrote: > On Tue, 29 Jun 2010 15:42:54 -0600 > Grant Likely wrote: > >> On Tue, Jun 29, 2010 at 9:03 AM, Andres Salomon >> wrote: > [...] >> >> > ?Sparc and OLPC have very similar >> > mechanisms for getting device tree info from OFW, so it makes sense >> > to share code between them. >> >> Other than the flattened tree step; is the powerpc method dissimilar >> from the Sparc and OLPC method for talking to OFW? ?(This is not a >> rhetorical question, I'm want to know if I'm missing some details). >> The main difference I know about is that OFW can still kept alive at >> runtime for sparc, which powerpc does not do. ?However, keeping OFW >> callable is a separate issue from how to extract the device tree. >> > > After having a look at powerpc's flatten_device_tree, I don't see any > obvious reason why OLPC couldn't use this Okay. >(though it still strikes me > as weird to go from prom->fdt->dt when the option of prom->dt is > available and less complex). Which is why I didn't simply NACK it out of hand. It is a valid point. I'd probably be happier if both fdt and pdt used a shared set of utility functions for allocating and tying together the device_node data structures. Then at least there would be only one instance of code to deal with the fiddly data structure interconnections. The nice thing about the powerpc version is that the tree can be extracted really early in the boot process, before any of the core kernel infrastructure or memory management is initialized. > Do you already have the patches that put > this into drivers/of/? No. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. -- 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/