From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rn-out-0910.google.com (rn-out-0910.google.com [64.233.170.186]) by ozlabs.org (Postfix) with ESMTP id 82488DDE1B for ; Tue, 8 Jul 2008 04:51:30 +1000 (EST) Received: by rn-out-0910.google.com with SMTP id j40so503514rnf.16 for ; Mon, 07 Jul 2008 11:51:28 -0700 (PDT) Message-ID: <9e4733910807071151m8cac0fob63f9663457da2f1@mail.gmail.com> Date: Mon, 7 Jul 2008 14:51:28 -0400 From: "Jon Smirl" To: "Grant Likely" Subject: Re: [PATCH] Add MPC5200B base board mvBC-P In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <486E515B.80508@matrix-vision.de> <20080706235046.GA6267@yookeroo.seuss> <4871CA6E.9080805@matrix-vision.de> Cc: linux-ppc list , Andre Schwarz , David Gibson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 7/7/08, Grant Likely wrote: > On Mon, Jul 7, 2008 at 1:49 AM, Andre Schwarz > wrote: > > David, > > > > thanks - removed "device_type" from the DMA controller. > > > > Which nodes actually require "device_type" and which don't ? > > > > Is there some general rule ? > > > Segher, David; > > In OF, what is the purpose of device_type? From what I understand > right now, each value of device_type claims a software interface that > the device supports. So for example, device_type = "serial" means > that firmware supports using the device as a serial port, correct? > So, similarly, if OF did not have a driver for the device, then the > presence a device_type property would be a bug, right? > > Does device_type indicated any other information other than firmware > driver interface? > > I had an epiphany about device_type this weekend (and by epiphany, I > mean realizing my own stupidity). If I'm correct about the above > questions, then that would mean it is *always* a bug to have a > device_type property in .dts file because there is no firmware > interface. So, it seems to me that we shouldn't just be eliminating > undefined device_type values, but also eliminate the ones that are > defined in OF because .dts users do not support the firmware driver > interface. > > Am I correct? > > The only situation where I can see it being appropriate to specify > device_type is to work around older bindings that are ambiguous with > their other properties. I experimented with this on my own trees. device_type = "serial"; Is current required on the boot console or it will disappear. -- Jon Smirl jonsmirl@gmail.com