[PATCH 4.19 11/81] xhci: Fix USB 3.1 capability detection on early xHCI 1.1 spec based hosts

[Greg Kroah-Hartman]

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

commit 47f50d61076523e1a0d5a070062c2311320eeca8 upstream.

Early xHCI 1.1 spec did not mention USB 3.1 capable hosts should set
sbrn to 0x31, or that the minor revision is a two digit BCD
containing minor and sub-minor numbers.
This was later clarified in xHCI 1.2.

Some USB 3.1 capable hosts therefore have sbrn set to 0x30, or minor
revision set to 0x1 instead of 0x10.

Detect the USB 3.1 capability correctly for these hosts as well

Fixes: ddd57980a0fd ("xhci: detect USB 3.2 capable host controllers correctly")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.18+
Cc: LoÃc Yhuel <loic.yhuel@xxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1570190373-30684-5-git-send-email-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -5036,11 +5036,18 @@ int xhci_gen_setup(struct usb_hcd *hcd,
 		hcd->has_tt = 1;
 	} else {
 		/*
-		 * Some 3.1 hosts return sbrn 0x30, use xhci supported protocol
-		 * minor revision instead of sbrn. Minor revision is a two digit
-		 * BCD containing minor and sub-minor numbers, only show minor.
+		 * Early xHCI 1.1 spec did not mention USB 3.1 capable hosts
+		 * should return 0x31 for sbrn, or that the minor revision
+		 * is a two digit BCD containig minor and sub-minor numbers.
+		 * This was later clarified in xHCI 1.2.
+		 *
+		 * Some USB 3.1 capable hosts therefore have sbrn 0x30, and
+		 * minor revision set to 0x1 instead of 0x10.
 		 */
-		minor_rev = xhci->usb3_rhub.min_rev / 0x10;
+		if (xhci->usb3_rhub.min_rev == 0x1)
+			minor_rev = 1;
+		else
+			minor_rev = xhci->usb3_rhub.min_rev / 0x10;
 
 		switch (minor_rev) {
 		case 2: