[PATCH 3.13 038/151] xhci: Prevent runtime pm from autosuspending during initialization

Kamal Mostafa kamal at canonical.com
Fri May 2 15:37:06 UTC 2014 -stable review patch.  If anyone has any objections, please let me know.


From: Mathias Nyman <mathias.nyman at linux.intel.com>

commit bcffae7708eb8352f44dc510b326541fe43a02a4 upstream.

xHCI driver has its own pci probe function that will call usb_hcd_pci_probe
to register its usb-2 bus, and then continue to manually register the
usb-3 bus. usb_hcd_pci_probe does a pm_runtime_put_noidle at the end and
might thus trigger a runtime suspend before the usb-3 bus is ready.

Prevent the runtime suspend by increasing the usage count in the
beginning of xhci_pci_probe, and decrease it once the usb-3 bus is

xhci-platform driver is not using usb_hcd_pci_probe to set up
busses and should not need to have it's usage count increased during probe.

Signed-off-by: Mathias Nyman <mathias.nyman at linux.intel.com>
Acked-by: Dan Williams <dan.j.williams at intel.com>
Acked-by: Alan Stern <stern at rowland.harvard.edu>
Signed-off-by: Sarah Sharp <sarah.a.sharp at linux.intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/usb/host/xhci-pci.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 1af67a2..d069224 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -190,6 +190,10 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	struct usb_hcd *hcd;
 	driver = (struct hc_driver *)id->driver_data;
+	/* Prevent runtime suspending between USB-2 and USB-3 initialization */
+	pm_runtime_get_noresume(&dev->dev);
 	/* Register the USB 2.0 roothub.
 	 * FIXME: USB core must know to register the USB 2.0 roothub first.
 	 * This is sort of silly, because we could just set the HCD driver flags
@@ -199,7 +203,7 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	retval = usb_hcd_pci_probe(dev, id);
 	if (retval)
-		return retval;
+		goto put_runtime_pm;
 	/* USB 2.0 roothub is stored in the PCI device now. */
 	hcd = dev_get_drvdata(&dev->dev);
@@ -228,12 +232,17 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (xhci->quirks & XHCI_LPM_SUPPORT)
 		hcd_to_bus(xhci->shared_hcd)->root_hub->lpm_capable = 1;
+	/* USB-2 and USB-3 roothubs initialized, allow runtime pm suspend */
+	pm_runtime_put_noidle(&dev->dev);
 	return 0;
+	pm_runtime_put_noidle(&dev->dev);
 	return retval;

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