1 files changed, 24 insertions, 12 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index b3c09e4c8492..3c54b218301c 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4728,7 +4728,7 @@ static int get_bMaxPacketSize0(struct usb_device *udev,
 				buf, size,
 				initial_descriptor_timeout);
 		switch (buf->bMaxPacketSize0) {
-		case 8: case 16: case 32: case 64: case 255:
+		case 8: case 16: case 32: case 64: case 9:
 			if (buf->bDescriptorType == USB_DT_DEVICE) {
 				rc = buf->bMaxPacketSize0;
 				break;
@@ -5015,23 +5015,35 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
 	if (retval)
 		goto fail;
 
-	if (maxp0 == 0xff || udev->speed >= USB_SPEED_SUPER)
-		i = 512;
-	else
-		i = maxp0;
-	if (usb_endpoint_maxp(&udev->ep0.desc) != i) {
-		if (udev->speed == USB_SPEED_LOW ||
-				!(i == 8 || i == 16 || i == 32 || i == 64)) {
-			dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", i);
-			retval = -EMSGSIZE;
-			goto fail;
-		}
+	/*
+	 * Check the ep0 maxpacket guess and correct it if necessary.
+	 * maxp0 is the value stored in the device descriptor;
+	 * i is the value it encodes (logarithmic for SuperSpeed or greater).
+	 */
+	i = maxp0;
+	if (udev->speed >= USB_SPEED_SUPER) {
+		if (maxp0 <= 16)
+			i = 1 << maxp0;
+		else
+			i = 0;		/* Invalid */
+	}
+	if (usb_endpoint_maxp(&udev->ep0.desc) == i) {
+		;	/* Initial ep0 maxpacket guess is right */
+	} else if ((udev->speed == USB_SPEED_FULL ||
+				udev->speed == USB_SPEED_HIGH) &&
+			(i == 8 || i == 16 || i == 32 || i == 64)) {
+		/* Initial guess is wrong; use the descriptor's value */
 		if (udev->speed == USB_SPEED_FULL)
 			dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
 		else
 			dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i);
 		udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
 		usb_ep0_reinit(udev);
+	} else {
+		/* Initial guess is wrong and descriptor's value is invalid */
+		dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", maxp0);
+		retval = -EMSGSIZE;
+		goto fail;
 	}
 
 	descr = usb_get_device_descriptor(udev);