[PATCH v3 6/8] usb: xhci: Fix port minor revision

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

Some hosts incorrectly use sub-minor version for minor version (i.e.
0x02 instead of 0x20 for bcdUSB 0x320 and 0x01 for bcdUSB 0x310).
Currently the xHCI driver works around this by just checking for minor
revision > 0x01 for USB 3.1 everywhere. With the addition of USB 3.2,
checking this gets a bit cumbersome. Since there is no USB release with
bcdUSB 0x301 to 0x309, we can assume that sub-minor version 01 to 09 is
incorrect. Let's try to fix this and use the minor revision that matches
with the USB/xHCI spec to help with the version checking within the
driver.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
Changes in v3:
- Use comparison operators > < instead of & operation for easier read
Changes in v2:
- Use <<= when shift and assign value instead

 drivers/usb/host/xhci-mem.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 7eb8c07c8418..34d95c006751 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2129,6 +2129,15 @@ static void xhci_add_in_port(struct xhci_hcd *xhci, unsigned int num_ports,
 
 	if (major_revision == 0x03) {
 		rhub = &xhci->usb3_rhub;
+		/*
+		 * Some hosts incorrectly use sub-minor version for minor
+		 * version (i.e. 0x02 instead of 0x20 for bcdUSB 0x320 and 0x01
+		 * for bcdUSB 0x310). Since there is no USB release with sub
+		 * minor version 0x301 to 0x309, we can assume that they are
+		 * incorrect and fix it here.
+		 */
+		if (minor_revision > 0x00 && minor_revision < 0x10)
+			minor_revision <<= 4;
 	} else if (major_revision <= 0x02) {
 		rhub = &xhci->usb2_rhub;
 	} else {
-- 
2.28.0