[BUGFIX,-v3,2/4] PCI/PM: Keep parent bridge active when probing device

Submitted by Huang Ying on Aug. 8, 2012, 1:07 a.m.


Message ID 1344388061-18981-3-git-send-email-ying.huang@intel.com
State Accepted
Headers show

Commit Message

Huang Ying Aug. 8, 2012, 1:07 a.m.
This patch fixes the following bug:


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 <bjorn@mork.no>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
 drivers/pci/pci-driver.c |    6 ++++++
 1 file changed, 6 insertions(+)

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--- 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)
+	if (parent)
+		pm_runtime_put(parent);
 	return rc;