From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.sh.mvista.com (unknown [63.81.120.155]) by ozlabs.org (Postfix) with ESMTP id 9A9A2DDF52 for ; Sat, 25 Aug 2007 05:08:03 +1000 (EST) Message-ID: <46CF2D2C.2050306@ru.mvista.com> Date: Fri, 24 Aug 2007 23:10:36 +0400 From: Sergei Shtylyov MIME-Version: 1.0 To: Segher Boessenkool Subject: Re: [PATCH 2/6] PowerPC 440EPx: Sequoia DTS References: <20070730150648.GA5005@ru.mvista.com> <20070801020836.GB31391@localhost.localdomain> <65ff446478a9fd0a48061079d5f04f8f@kernel.crashing.org> <20070801050422.GI31391@localhost.localdomain> <20070801054751.GM31391@localhost.localdomain> <46B1F6D4.3070707@ru.mvista.com> <20070803031349.GD6418@localhost.localdomain> <46B34E1F.5060009@ru.mvista.com> <20070806042109.GB6103@localhost.localdomain> <163e1bcdc507ddcde3193e842c96da43@kernel.crashing.org> <20070807041259.GF13522@localhost.localdomain> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Cc: linuxppc-dev@ozlabs.org, David Gibson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Segher Boessenkool wrote: >>>address-permutation = <0 1 3 2 4 5 7 6 e f d c a b 9 8>; >>Yes, I was contemplating something like that. > Let's not define this until we need it though :-) Let's ot even think of it, since this will end up in a "catch all" driver, and yet this may be not enough when the flash doesn't support 8-but R/W, for example (I've already quoted it... >>>I haven't heard or thought of anything better either. Using "ranges" >>>is conceptually wrong, even ignoring the technical problems that come >>>with it. >>Why is "ranges" conceptually wrong? > The flash partitions aren't separate devices sitting on a Yeah, that's why I decided not to go that from the very start... though wait: I didn't do this simply because they'renot devices. That lead me to interesting question: do device tree have something for the disk partitions? > "flash bus", they are "sub-devices" of their parent. They're quite an abstaction of a device -- althogh Linux treats them as separate devices indeed. >>To be honest this looks rather to me like another case where having >>overlapping 'reg' and 'ranges' would actually make sense. > It never makes sense. You should give the "master" device > the full "reg" range it covers, and have it define its own > address space; "sub-devices" can carve out their little hunk > from that. You don't want more than one device owning the > same address range in the same address space. So, no "ranges" prop in MTD node is necessary? Phew... :-) > Segher WBR, Sergei