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 0112b7ce68ea ("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: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")
Cc: stable@vger.kernel.org
Signed-off-by: Tomas Marek <tomas.marek@elrest.cz>
Link: https://lore.kernel.org/r/20240906055025.25057-1-tomas.marek@elrest.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c
index a8605b02115b1c3d0c6038c1dbb72e0e9ab3bac9..1ad8fa3f862a151e0835f4b927fee277fb92c58d 100644 (file)
--- a/drivers/usb/dwc2/drd.c
+++ b/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) {