Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754163Ab2HCOqX (ORCPT ); Fri, 3 Aug 2012 10:46:23 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:55596 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753052Ab2HCOqV (ORCPT ); Fri, 3 Aug 2012 10:46:21 -0400 Date: Fri, 3 Aug 2012 10:46:20 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Huang Ying cc: Bjorn Helgaas , , , , "Rafael J. Wysocki" Subject: Re: [BUGFIX 3/4] PCI/PM: Fix config reg access for D3cold and bridge suspending In-Reply-To: <1343975435-25469-4-git-send-email-ying.huang@intel.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1552 Lines: 47 On Fri, 3 Aug 2012, Huang Ying wrote: > This patch fixes the following bug: > > http://marc.info/?l=linux-pci&m=134338059022620&w=2 > > Where lspci does not work properly if a device and the corresponding > parent bridge (such as PCIe port) is suspended. This is because the > device configuration space registers will be not accessible if the > corresponding parent bridge is suspended or the device is put into > D3cold state. > > To solve the issue, the bridge/PCIe port connected to the device is > put into active state before read/write configuration space registers. > If the device is in D3cold state, it will be put into active state > too. > > To avoid resume/suspend PCIe port for each configuration register > read/write, a small delay is added before the PCIe port to go > suspended. > +static void > +pci_config_pm_runtime_put(struct pci_dev *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct device *parent = dev->parent; > + > + pm_runtime_put(dev); > + if (parent) > + pm_runtime_put(parent); > +} This is just the sort of thing Rafael and I have been talking about. Why do an asynchronous put, going to all the trouble of using the workqueue, if the idle routine is just going to call pm_schedule_suspend()? Why not call pm_runtime_put_sync() instead? Alan Stern -- 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/