From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 15 Feb 2007 10:27:01 +1100 From: David Gibson To: Yoder Stuart-B08248 Subject: Re: [PATCH 15/16] Add device tree for Ebony Message-ID: <20070214232701.GF16279@localhost.localdomain> References: <20070213060904.GA6214@localhost.localdomain> <20070213061026.5837FDDDE9@ozlabs.org> <9696D7A991D0824DBA8DFAC74A9C5FA302A1B705@az33exm25.fsl.freescale.net> <1171470754.4003.101.camel@zod.rchland.ibm.com> <6206de08b7f12175bebe669291c66334@kernel.crashing.org> <9696D7A991D0824DBA8DFAC74A9C5FA302A1B86F@az33exm25.fsl.freescale.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <9696D7A991D0824DBA8DFAC74A9C5FA302A1B86F@az33exm25.fsl.freescale.net> Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Feb 14, 2007 at 01:08:01PM -0700, Yoder Stuart-B08248 wrote: > > > >> Hmm. There are two "soc" devices here, one nested under the > > >> first?? > > >> > > >> I'm assuming these are two levels of busses the opb bus is attached > > >> to the plb bus. Is the "soc" device_type the right way to > > >> do this? > > > > > > Right, OPB hangs off of PLB in this case. I dunno if "soc" is the > > > right > > > device type for them though. > > > > I would use device_type "plb" (or "plb4") and "opb" I think. > > Similar to how PCI and ISA etc. busses are represented. > > I think we should avoid making up new device_types unlesss it > really is necessary. > > Is it really necessary to distinguish between devices on > the PLB or OPB? Well.. maybe. There are registers (DCR, not MMIO) in the PLB<->OPB bridge. I don't think the actual mapping can be changed, but some error reporting and arbitration are controller there. I think it's better to represent the two busses, in case the distinction becomes important at some point. > As I undestand it the "soc" device type is a logical container > for a group of devices in an SOC, not necessarily a group > of devices on the same bus. Could we simply list all those > devices under an "soc" node at the same level. > > If for some reason the bus hierarchy distinction _is_ required, > my suggestion would be to create new generic device type for > representing an internal bus. The "device_type" is supposed > to be somewhat general-- "network", "serial", etc. > > We could create something like "soc-bus" or "internal-bus" with > a compatible field that identifies the type of bus. > > The general philosophy is a general device_type prooperty and > a specific compatible property. Yes, that's partly why I'm using "soc" for now. I've thought that a new general device_type might be a good idea though. What's a "soc" and what's an "internal" bus I think are not necessarily clear, though. I would suggest a type for any memory mapped, non-hotpluggable, non-probeable bus. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson