usb: dwc3: Update maximum_speed for SuperSpeedPlus

If the maximum_speed is not set, set it to a known value, either
SuperSpeed or SuperSpeedPlus based on the type of controller we are
using. If we are on DWC_usb31 controller, check the PHY interface to see
if it is capable of SuperSpeedPlus.

Also this check is moved after dwc3_core_init() so that we can check
dwc->revision.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/dwc3/core.c

@@ -962,10 +962,6 @@ static int dwc3_probe(struct platform_device *pdev)
 		fladj = pdata->fladj_value;
 	}
 
-	/* default to superspeed if no maximum_speed passed */
-	if (dwc->maximum_speed == USB_SPEED_UNKNOWN)
-		dwc->maximum_speed = USB_SPEED_SUPER;
-
 	dwc->lpm_nyet_threshold = lpm_nyet_threshold;
 	dwc->tx_de_emphasis = tx_de_emphasis;
 
@@ -1016,6 +1012,19 @@ static int dwc3_probe(struct platform_device *pdev)
 		goto err1;
 	}
 
+	/* default to superspeed if no maximum_speed passed */
+	if (dwc->maximum_speed == USB_SPEED_UNKNOWN) {
+		dwc->maximum_speed = USB_SPEED_SUPER;
+
+		/*
+		 * default to superspeed plus if we are capable.
+		 */
+		if (dwc3_is_usb31(dwc) &&
+		    (DWC3_GHWPARAMS3_SSPHY_IFC(dwc->hwparams.hwparams3) ==
+		     DWC3_GHWPARAMS3_SSPHY_IFC_GEN2))
+			dwc->maximum_speed = USB_SPEED_SUPER_PLUS;
+	}
+
 	/* Adjust Frame Length */
 	dwc3_frame_length_adjustment(dwc, fladj);