Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754560Ab2B0Uti (ORCPT ); Mon, 27 Feb 2012 15:49:38 -0500 Received: from mail-qw0-f46.google.com ([209.85.216.46]:36998 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753439Ab2B0Uth convert rfc822-to-8bit (ORCPT ); Mon, 27 Feb 2012 15:49:37 -0500 MIME-Version: 1.0 In-Reply-To: References: <1330299202-3838-1-git-send-email-yinghai@kernel.org> <1330299202-3838-6-git-send-email-yinghai@kernel.org> Date: Mon, 27 Feb 2012 12:49:36 -0800 X-Google-Sender-Auth: t8WW1WJjvniTPkeQVxUF6V3L0j0 Message-ID: Subject: Re: [PATCH 5/8] PCI: add generic device into pci_host_bridge struct From: Yinghai Lu To: Bjorn Helgaas Cc: Jesse Barnes , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1508 Lines: 42 On Mon, Feb 27, 2012 at 11:17 AM, Bjorn Helgaas wrote: > On Mon, Feb 27, 2012 at 12:08 PM, Yinghai Lu wrote: >>> This doesn't feel right to me. ?You're allocating a new struct device >>> here, but the arch likely already has one. ?In fact, I think we even >>> passed it in to pci_create_root_bus(). >> >> no. >> >> original pci_create_root_bus() will create one dummy struct device and >> use it as parent for bus->dev. >> >>> >>> On x86, we already have an ACPI device for the host bridge, and now >>> we'll have a second one. ?(Actually a *third* one, because PNPACPI >>> also has one, but that's a long-standing problem.) >> >> not related. > > OK. ?Can you educate me? ?What is the device we pass in, what does the > dummy one correspond to, why do we have two, what's the difference, > etc., etc.? for every bus will have ->bridge, and that is device pointer. to pci bridge dev. for root bus, there is not pci bridge for that. So create_root_bus allocate local dummy one. that dummy device will be bus->dev's parent. Now pci_host_bridge is added, and it is allocated, so just put the struct device into that pci_host_bridge. and use pci_host_bridge->dev as parent of root bus->dev's parent. Yinghai -- 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/