From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Huang Ying To: Bjorn Helgaas Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Huang Ying , Alan Stern Subject: [BUGFIX -v2 2/4] PCI/PM: Keep parent bridge active when probing device Date: Mon, 6 Aug 2012 09:34:28 +0800 Message-Id: <1344216870-21105-3-git-send-email-ying.huang@intel.com> In-Reply-To: <1344216870-21105-1-git-send-email-ying.huang@intel.com> References: <1344216870-21105-1-git-send-email-ying.huang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: This patch fixes the following bug: http://marc.info/?l=linux-pci&m=134329923124234&w=2 The root cause of the bug is as follow. If a device is not bound with the corresponding driver, the device runtime PM will be disabled and the device will be put into suspended state. So that, the bridge/PCIe port connected to it may be put into suspended and low power state. When do probing for the device later, because the bridge/PCIe port connected to it is in low power state, the IO access to device may fail. To solve the issue, the bridge/PCIe port connected to the device is put into active state before probing. Reported-by: Bjorn Mork Signed-off-by: Huang Ying Reviewed-by: Rafael J. Wysocki --- drivers/pci/pci-driver.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -280,8 +280,12 @@ static long local_pci_probe(void *_ddi) { struct drv_dev_and_id *ddi = _ddi; struct device *dev = &ddi->dev->dev; + struct device *parent = dev->parent; int rc; + /* The parent bridge must be in active state when probing */ + if (parent) + pm_runtime_get_sync(parent); /* Unbound PCI devices are always set to disabled and suspended. * During probe, the device is set to enabled and active and the * usage count is incremented. If the driver supports runtime PM, @@ -298,6 +302,8 @@ static long local_pci_probe(void *_ddi) pm_runtime_set_suspended(dev); pm_runtime_put_noidle(dev); } + if (parent) + pm_runtime_put(parent); return rc; }