usb: dwc2: drd: fix clock gating on USB role switch

The dwc2_handle_usb_suspend_intr() function disables gadget clocks in USB
peripheral mode when no other power-down mode is available (introduced by
commit 0112b7c ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")).
However, the dwc2_drd_role_sw_set() USB role update handler attempts to
read DWC2 registers if the USB role has changed while the USB is in suspend
mode (when the clocks are gated). This causes the system to hang.

Release the gadget clocks before handling the USB role update.

Fixes: 0112b7c ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")
Cc: [email protected]
Signed-off-by: Tomas Marek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Tomas Marek

drivers/usb/dwc2/drd.c

@@ -127,6 +127,15 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
 			role = USB_ROLE_DEVICE;
 	}
 
+	if ((IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) ||
+	     IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)) &&
+	     dwc2_is_device_mode(hsotg) &&
+	     hsotg->lx_state == DWC2_L2 &&
+	     hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_NONE &&
+	     hsotg->bus_suspended &&
+	     !hsotg->params.no_clock_gating)
+		dwc2_gadget_exit_clock_gating(hsotg, 0);
+
 	if (role == USB_ROLE_HOST) {
 		already = dwc2_ovr_avalid(hsotg, true);
 	} else if (role == USB_ROLE_DEVICE) {