usb: renesas_usbhs: add wait after initialization for R-Car Gen3

Since the controller on R-Car Gen3 doesn't have any status registers
to detect initialization (LPSTS.SUSPM = 1) and the initialization needs
up to 45 usec, this patch adds wait after the initialization. Otherwise,
writing other registers (e.g. INTENB0) will fail.

Fixes: de18757e272d ("usb: renesas_usbhs: add R-Car Gen3 power control")
Cc: <stable@vger.kernel.org> # v4.6+
Cc: <balbi@kernel.org>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/renesas_usbhs/rcar3.c

@@ -9,6 +9,7 @@
  *
  */
 
+#include <linux/delay.h>
 #include <linux/io.h>
 #include "common.h"
 #include "rcar3.h"
@@ -35,10 +36,13 @@ static int usbhs_rcar3_power_ctrl(struct platform_device *pdev,
 
 	usbhs_write32(priv, UGCTRL2, UGCTRL2_RESERVED_3 | UGCTRL2_USB0SEL_OTG);
 
-	if (enable)
+	if (enable) {
 		usbhs_bset(priv, LPSTS, LPSTS_SUSPM, LPSTS_SUSPM);
-	else
+		/* The controller on R-Car Gen3 needs to wait up to 45 usec */
+		udelay(45);
+	} else {
 		usbhs_bset(priv, LPSTS, LPSTS_SUSPM, 0);
+	}
 
 	return 0;
 }