From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761558Ab3BNShR (ORCPT ); Thu, 14 Feb 2013 13:37:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:9933 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758463Ab3BNShP (ORCPT ); Thu, 14 Feb 2013 13:37:15 -0500 Subject: [PATCH] pci: Disable slot presence detection around bus reset To: bhelgaas@google.com, linux-pci@vger.kernel.org From: Alex Williamson Cc: linux-kernel@vger.kernel.org Date: Thu, 14 Feb 2013 11:37:13 -0700 Message-ID: <20130214183640.16220.33060.stgit@bling.home> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A bus reset can trigger a presence detection change and result in a suprise hotplug. This is generally not what we want to happen when trying to reset a device. Disable the presence detection control on on bridges around bus reset. Signed-off-by: Alex Williamson --- drivers/pci/pci.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 5cb5820..c1f7d77 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3229,8 +3229,8 @@ static int pci_pm_reset(struct pci_dev *dev, int probe) static int pci_parent_bus_reset(struct pci_dev *dev, int probe) { - u16 ctrl; - struct pci_dev *pdev; + u16 ctrl, flags, sltctl = 0; + struct pci_dev *pdev, *bridge; if (pci_is_root_bus(dev->bus) || dev->subordinate || !dev->bus->self) return -ENOTTY; @@ -3242,15 +3242,34 @@ static int pci_parent_bus_reset(struct pci_dev *dev, int probe) if (probe) return 0; - pci_read_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, &ctrl); + bridge = dev->bus->self; + + /* + * If the parent device supports a slot with presence detection + * change enabled, holding the bus in reset can trigger that and + * cause an unwanted surprise removal. Disable presence detection + * around the bus reset. + */ + pcie_capability_read_word(bridge, PCI_EXP_FLAGS, &flags); + if (flags & PCI_EXP_FLAGS_SLOT) { + pcie_capability_read_word(bridge, PCI_EXP_SLTCTL, &sltctl); + if (sltctl & PCI_EXP_SLTCTL_PDCE) + pcie_capability_write_word(bridge, PCI_EXP_SLTCTL, + sltctl & ~PCI_EXP_SLTCTL_PDCE); + } + + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &ctrl); ctrl |= PCI_BRIDGE_CTL_BUS_RESET; - pci_write_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, ctrl); + pci_write_config_word(bridge, PCI_BRIDGE_CONTROL, ctrl); msleep(100); ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET; - pci_write_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, ctrl); + pci_write_config_word(bridge, PCI_BRIDGE_CONTROL, ctrl); msleep(100); + if (sltctl & PCI_EXP_SLTCTL_PDCE) + pcie_capability_write_word(bridge, PCI_EXP_SLTCTL, sltctl); + return 0; }