usb: chipidea: fix no transceiver case

Since usb phy code does return ERR_PTR() values, make sure that we don't
end up dereferencing them. This is a problem, for example, on platforms
that don't register a phy for chipidea since b7fa5c2a ("usb: phy: return
-ENXIO when PHY layer isn't enabled").
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/udc.c

@@ -1678,8 +1678,11 @@ static int udc_start(struct ci13xxx *ci)
 
 	ci->gadget.ep0 = &ci->ep0in->ep;
 
-	if (ci->global_phy)
+	if (ci->global_phy) {
 		ci->transceiver = usb_get_phy(USB_PHY_TYPE_USB2);
+		if (IS_ERR(ci->transceiver))
+			ci->transceiver = NULL;
+	}
 
 	if (ci->platdata->flags & CI13XXX_REQUIRE_TRANSCEIVER) {
 		if (ci->transceiver == NULL) {
@@ -1694,7 +1697,7 @@ static int udc_start(struct ci13xxx *ci)
 			goto put_transceiver;
 	}
 
-	if (!IS_ERR_OR_NULL(ci->transceiver)) {
+	if (ci->transceiver) {
 		retval = otg_set_peripheral(ci->transceiver->otg,
 						&ci->gadget);
 		if (retval)
@@ -1711,7 +1714,7 @@ static int udc_start(struct ci13xxx *ci)
 	return retval;
 
 remove_trans:
-	if (!IS_ERR_OR_NULL(ci->transceiver)) {
+	if (ci->transceiver) {
 		otg_set_peripheral(ci->transceiver->otg, NULL);
 		if (ci->global_phy)
 			usb_put_phy(ci->transceiver);
@@ -1719,7 +1722,7 @@ static int udc_start(struct ci13xxx *ci)
 
 	dev_err(dev, "error = %i\n", retval);
 put_transceiver:
-	if (!IS_ERR_OR_NULL(ci->transceiver) && ci->global_phy)
+	if (ci->transceiver && ci->global_phy)
 		usb_put_phy(ci->transceiver);
 destroy_eps:
 	destroy_eps(ci);
@@ -1747,7 +1750,7 @@ static void udc_stop(struct ci13xxx *ci)
 	dma_pool_destroy(ci->td_pool);
 	dma_pool_destroy(ci->qh_pool);
 
-	if (!IS_ERR_OR_NULL(ci->transceiver)) {
+	if (ci->transceiver) {
 		otg_set_peripheral(ci->transceiver->otg, NULL);
 		if (ci->global_phy)
 			usb_put_phy(ci->transceiver);