diff options
Diffstat (limited to 'drivers/usb/host/xhci-pci.c')
| -rw-r--r-- | drivers/usb/host/xhci-pci.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c index cbc4d491e626..faf039ac6573 100644 --- a/drivers/usb/host/xhci-pci.c +++ b/drivers/usb/host/xhci-pci.c @@ -242,8 +242,28 @@ static int xhci_pci_suspend(struct usb_hcd *hcd, bool do_wakeup) static int xhci_pci_resume(struct usb_hcd *hcd, bool hibernated) { struct xhci_hcd *xhci = hcd_to_xhci(hcd); + struct pci_dev *pdev = to_pci_dev(hcd->self.controller); int retval = 0; + /* 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_xhci(pdev)) + usb_enable_xhci_ports(pdev); + retval = xhci_resume(xhci, hibernated); return retval; } |