Merge branch 'for-usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sarah/xhci

* 'for-usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sarah/xhci:
  Intel xhci: Limit number of active endpoints to 64.
  Intel xhci: Ignore spurious successful event.
  Intel xhci: Support EHCI/xHCI port switching.
  Intel xhci: Add PCI id for Panther Point xHCI host.
  xhci: STFU: Be quieter during URB submission and completion.
  xhci: STFU: Don't print event ring dequeue pointer.
  xhci: STFU: Remove function tracing.
  xhci: Don't submit commands when the host is dead.
  xhci: Clear stopped_td when Stop Endpoint command completes.

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 660b80a75ca..1102ce65a3a 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -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))