Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932508AbbDOM4U (ORCPT ); Wed, 15 Apr 2015 08:56:20 -0400 Received: from mail-qk0-f176.google.com ([209.85.220.176]:35914 "EHLO mail-qk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932405AbbDOM4N (ORCPT ); Wed, 15 Apr 2015 08:56:13 -0400 MIME-Version: 1.0 In-Reply-To: <2638174.Fqeb1nNFUX@vostro.rjw.lan> References: <2001450.KHHLaZsp3O@vostro.rjw.lan> <1429025292.3383705.253616133.4A1DF301@webmail.messagingengine.com> <2638174.Fqeb1nNFUX@vostro.rjw.lan> From: Bjorn Helgaas Date: Wed, 15 Apr 2015 07:55:26 -0500 Message-ID: Subject: Re: [PATCH] PCI / hotplug: Propagate the "ignore hotplug" setting to parent To: "Rafael J. Wysocki" Cc: Henrique de Moraes Holschuh , Linux PCI , ACPI Devel Maling List , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1741 Lines: 33 On Tue, Apr 14, 2015 at 8:03 PM, Rafael J. Wysocki wrote: > On Tuesday, April 14, 2015 12:28:12 PM Henrique de Moraes Holschuh wrote: >> On Mon, Apr 13, 2015, at 11:23, Rafael J. Wysocki wrote: >> > From: Rafael J. Wysocki >> > >> > Refine the mechanism introduced by commit f244d8b623da (ACPIPHP / radeon >> > / nouveau: Fix VGA switcheroo problem related to hotplug) to propagate >> > the ignore_hotplug setting of the device to its parent bridge in case >> > hotplug notifications related to the graphics adapter switching are >> > given for the bridge rather than for the device itself (the need to >> > be ignored in both cases). >> >> I do apologise if this is a stupid question, but is there any chance the >> bridge will be connected to other devices that do require hotplug handling, >> and not just to the GPU? > > The bridge is actually a downstream PCIe port holding the GPU, so no. :-) When radeon/nouveau call pci_ignore_hotplug(), that's the case, but in general all we know is that pci_ignore_hotplug() receives a PCI device. We don't know whether it's PCI or PCIe. In the hotplug topologies I'm familiar with, a bridge only leads to one hot-pluggable slot, but I don't remember anything that would guarantee that. For PCIe, I think there can only be one slot, but for PCI I would think it possible to have one bridge leading to several hotpluggable slots, with the hotplug controller(s) being separate from the bridge. 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/