Merge branch 'next' into for-linus

1 files changed, 40 insertions, 1 deletions

diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index d5eaea7caf8..1102ce65a3a 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -70,7 +70,7 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
 
 	ehci->caps = hcd->regs;
 	ehci->regs = hcd->regs +
-		HC_LENGTH(ehci_readl(ehci, &ehci->caps->hc_capbase));
+		HC_LENGTH(ehci, ehci_readl(ehci, &ehci->caps->hc_capbase));
 
 	dbg_hcs_params(ehci, "reset");
 	dbg_hcc_params(ehci, "reset");
@@ -348,11 +348,50 @@ static int ehci_pci_suspend(struct usb_hcd *hcd, bool do_wakeup)
 	return rc;
 }
 
+static bool usb_is_intel_switchable_ehci(struct pci_dev *pdev)
+{
+	return pdev->class == PCI_CLASS_SERIAL_USB_EHCI &&
+		pdev->vendor == PCI_VENDOR_ID_INTEL &&
+		pdev->device == 0x1E26;
+}
+
+static void ehci_enable_xhci_companion(void)
+{
+	struct pci_dev		*companion = NULL;
+
+	/* The xHCI and EHCI controllers are not on the same PCI slot */
+	for_each_pci_dev(companion) {
+		if (!usb_is_intel_switchable_xhci(companion))
+			continue;
+		usb_enable_xhci_ports(companion);
+		return;
+	}
+}
+
 static int ehci_pci_resume(struct usb_hcd *hcd, bool hibernated)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci(hcd);
 	struct pci_dev		*pdev = to_pci_dev(hcd->self.controller);
 
+	/* The BIOS on systems with the Intel Panther Point chipset may or may
+	 * not support xHCI natively.  That means that during system resume, it
+	 * may switch the ports back to EHCI so that users can use their
+	 * keyboard to select a kernel from GRUB after resume from hibernate.
+	 *
+	 * The BIOS is supposed to remember whether the OS had xHCI ports
+	 * enabled before resume, and switch the ports back to xHCI when the
+	 * BIOS/OS semaphore is written, but we all know we can't trust BIOS
+	 * writers.
+	 *
+	 * Unconditionally switch the ports back to xHCI after a system resume.
+	 * We can't tell whether the EHCI or xHCI controller will be resumed
+	 * first, so we have to do the port switchover in both drivers.  Writing
+	 * a '1' to the port switchover registers should have no effect if the
+	 * port was already switched over.
+	 */
+	if (usb_is_intel_switchable_ehci(pdev))
+		ehci_enable_xhci_companion();
+
 	// maybe restore FLADJ
 
 	if (time_before(jiffies, ehci->next_statechange))