USB: Don't fail USB3 probe on missing legacy PCI IRQ.

Intel has a PCI USB xhci host controller on a new platform. It doesn't
have a line IRQ definition in BIOS.  The Linux driver refuses to
initialize this controller, but Windows works well because it only depends
on MSI.

Actually, Linux also can work for MSI.  This patch avoids the line IRQ
checking for USB3 HCDs in usb core PCI probe.  It allows the xHCI driver
to try to enable MSI or MSI-X first.  It will fail the probe if MSI
enabling failed and there's no legacy PCI IRQ.

This patch should be backported to kernels as old as 2.6.32.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
index d136b8f4c8a..81e2c0d9c17 100644
--- a/drivers/usb/core/hcd-pci.c
+++ b/drivers/usb/core/hcd-pci.c
@@ -187,7 +187,10 @@ int usb_hcd_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
                 return -ENODEV;
         dev->current_state = PCI_D0;
 
-        if (!dev->irq) {
+        /* The xHCI driver supports MSI and MSI-X,
+         * so don't fail if the BIOS doesn't provide a legacy IRQ.
+         */
+        if (!dev->irq && (driver->flags & HCD_MASK) != HCD_USB3) {
                 dev_err(&dev->dev,
                         "Found HC with no IRQ.  Check BIOS/PCI %s setup!\n",
                         pci_name(dev));