Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752952Ab3FZVq1 (ORCPT ); Wed, 26 Jun 2013 17:46:27 -0400 Received: from mail-oa0-f45.google.com ([209.85.219.45]:59871 "EHLO mail-oa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902Ab3FZVqZ (ORCPT ); Wed, 26 Jun 2013 17:46:25 -0400 MIME-Version: 1.0 In-Reply-To: <51CB5D84.4080709@zytor.com> References: <83879b07cd4ce95f086420d1faa926c1692d63b4.1372211451.git.dvhart@linux.intel.com> <20130626163250.GA29299@google.com> <1372266904.8177.83.camel@envy.home> <51CB5D84.4080709@zytor.com> From: Bjorn Helgaas Date: Wed, 26 Jun 2013 15:46:04 -0600 Message-ID: Subject: Re: [PATCH 7/8] pci: Add CircuitCo VENDOR ID and MinnowBoard DEVICE ID To: "H. Peter Anvin" Cc: Darren Hart , Linux Kernel Mailing List , Peter P Waskiewicz Jr , Andy Shevchenko , danders@circuitco.com, vishal.l.verma@intel.com, "linux-pci@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1887 Lines: 41 On Wed, Jun 26, 2013 at 3:30 PM, H. Peter Anvin wrote: > On 06/26/2013 12:37 PM, Bjorn Helgaas wrote: >> >> Yeah, that's what I was thinking. >> >> But Peter's comment makes more sense to me now. The spec refers to >> that config register as "Subsystem ID," not "Subsystem Device ID," but >> I was confused because most existing usage treats it as a device ID. >> For example, the field in struct pci_device_id is named "subdevice," >> and all the existing #defines in pci_ids.h are of the form >> PCI_SUBDEVICE_ID_*. >> >> Device IDs are pretty specific identifiers, so I was thinking that a >> "sub-device ID" would be even more specific. Then it would make no >> sense to have a "sub-device ID" that was as generic as "MINNOWBOARD." >> But the register is actually *not* a "sub-device ID," and I can see >> that using the same Subsystem ID for all the devices on a board might >> make sense. >> > > Subsystem IDs is basically a board ID in the traditional PC view, but > they didn't call it that because it would have been confusing in other, > nontraditional configurations. > > Microsoft has a "best practices" document, which may end up becoming > basis for a future PCI-SIG document clarifying the standard: > > http://msdn.microsoft.com/en-us/library/windows/hardware/gg463287.aspx Interesting, thanks for the link. If I read that correctly, the MinnowBoard is basically a motherboard, and any board layout change or component value change will require a new Subsystem ID, which will in turn require a pch_gbe update. That doesn't sound optimal, but maybe people don't actually interpret it that strictly. Bjorn -- 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/