From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from puffin.external.hp.com (puffin.external.hp.com [192.25.206.4]) by dsl2.external.hp.com (Postfix) with ESMTP id C5F454A19 for ; Mon, 5 Feb 2001 11:19:55 -0700 (MST) Received: from mailserv2.iuinc.com (IDENT:qmailr@mailserv2.iuinc.com [206.245.164.55]) by puffin.external.hp.com (8.9.3/8.9.3) with SMTP id LAA29150 for ; Mon, 5 Feb 2001 11:15:40 -0700 Message-Id: <200102051822.KAA02233@milano.cup.hp.com> To: Ryan Bradetich Cc: parisc-linux@thepuffingroup.com Subject: Re: [parisc-linux] RFC: I/O tree design In-reply-to: Your message of "Sat, 03 Feb 2001 00:17:52 PST." <3A7BB0A0.D478911A@uswest.net> Date: Mon, 05 Feb 2001 10:22:11 -0800 From: Grant Grundler List-ID: Ryan Bradetich wrote: > Here is my proposal for phase 2 of the I/O tree for parisc-linux. Overall, this sounds ok to me. Just a nit WRT to terminology. ... > This proposal also calls for a special "root" node at > index 0 of the device array. The root node is the starting > point of the I/O tree and does not have a parent, nor any > siblings. The root node has a single child pointer which > points to the head of the sibling list for the system > bus. I would call the "root" node the "parent psuedo-bus adapter" (or something like that) of the central bus. It's special because it generally won't represent a physical PA I/O device. But it does contain a "lower port address" - the fixed PA IO address your previous bus-walk patch started with. The idea here is you can pass "hp_device *" to your PA bus walk code and not have seperate code for central bus or GSC bus. The bus walk code could use the "lower port address" as a new starting point to poke around. thanks, grant Grant Grundler parisc-linux {PCI|IOMMU|SMP} hacker +1.408.447.7253