Index: head/sys/mips/mediatek/mtk_usb_phy.c
===================================================================
--- head/sys/mips/mediatek/mtk_usb_phy.c
+++ head/sys/mips/mediatek/mtk_usb_phy.c
@@ -206,6 +206,11 @@
 	return (0);
 }
 
+/*
+ * Things currently seem to work a lot better without slew rate calibration
+ * both on MT7621 and MT7688, so we leave it out for now.
+ */
+#ifdef notyet
 static void
 mtk_usb_phy_slew_rate_calibration(struct mtk_usb_phy_softc *sc)
 {
@@ -250,10 +255,12 @@
 		USB_PHY_BARRIER(sc);
 	}
 }
+#endif
 
 static void
 mtk_usb_phy_mt7621_init(device_t dev)
 {
+#ifdef notyet
 	struct mtk_usb_phy_softc *sc = device_get_softc(dev);
 
 	/* Slew rate calibration only, but for 2 ports */
@@ -261,6 +268,7 @@
 
 	sc->u2_base = MT7621_U2_BASE_P1;
 	mtk_usb_phy_slew_rate_calibration(sc);
+#endif
 }
 
 static void
@@ -286,8 +294,10 @@
 	USB_PHY_WRITE_U2(sc, U2_PHY_DTM0, 0x02000000);
 	USB_PHY_BARRIER(sc);
 
+#ifdef notyet
 	/* Slew rate calibration */
-	//mtk_usb_phy_slew_rate_calibration(sc);
+	mtk_usb_phy_slew_rate_calibration(sc);
+#endif
 }
 
 static device_method_t mtk_usb_phy_methods[] = {