xhci: Fix USB 3.0 device restart on resume.

The xHCI hub port code gets passed a zero-based port number by the USB
core.  It then adds one to in order to find a device slot by port number
and device speed by calling xhci_find_slot_id_by_port.  That function
clearly states it requires a one-based port number.  The xHCI port
status change event handler was using a zero-based port number that it
got from find_faked_portnum_from_hw_portnum, not a one-based port
number.  This lead to the doorbells never being rung for a device after
a resume, or worse, a different device with the same speed having its
doorbell rung (which could lead to bad power management in the xHCI host
controller).

This patch should be backported to kernels as old as 2.6.39.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Andiry Xu <andiry.xu@amd.com>
Cc: stable@vger.kernel.org

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index b90e1386418b..5a818cbbab44 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1204,6 +1204,7 @@ static void handle_vendor_event(struct xhci_hcd *xhci,
  *
  * Returns a zero-based port number, which is suitable for indexing into each of
  * the split roothubs' port arrays and bus state arrays.
+ * Add one to it in order to call xhci_find_slot_id_by_port.
  */
 static unsigned int find_faked_portnum_from_hw_portnum(struct usb_hcd *hcd,
                 struct xhci_hcd *xhci, u32 port_id)
@@ -1324,7 +1325,7 @@ static void handle_port_status(struct xhci_hcd *xhci,
                         xhci_set_link_state(xhci, port_array, faked_port_index,
                                                 XDEV_U0);
                         slot_id = xhci_find_slot_id_by_port(hcd, xhci,
-                                        faked_port_index);
+                                        faked_port_index + 1);
                         if (!slot_id) {
                                 xhci_dbg(xhci, "slot_id is zero\n");
                                 goto cleanup;