[3.11.y.z extended stable] Patch "xhci: Prevent runtime pm from autosuspending during initialization" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    xhci: Prevent runtime pm from autosuspending during initialization

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 4f42dc5a6d27f317ac71b03034f04f4bd4dbaa9d Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman at linux.intel.com>
Date: Mon, 3 Mar 2014 19:30:17 +0200
Subject: xhci: Prevent runtime pm from autosuspending during initialization
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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
ready.

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: Luis Henriques <luis.henriques 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 c1f6005..9b9fa3e 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -185,6 +185,10 @@ 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
@@ -194,7 +198,7 @@ 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);
@@ -223,12 +227,17 @@ 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;

 put_usb3_hcd:
 	usb_put_hcd(xhci->shared_hcd);
 dealloc_usb2_hcd:
 	usb_hcd_pci_remove(dev);
+put_runtime_pm:
+	pm_runtime_put_noidle(&dev->dev);
 	return retval;
 }

--
1.9.1