drivers: udc_dwc2: Fix deactivate when hibernated

It is possible for usbd_disable() to be called when the core is
hibernated. When done so, the USB stack will attempt to deactivate all
the endpoints. Because the core is hibernated, register reads are
really undefined. This can lead to udc_dwc2_ep_deactivate() not calling
udc_dwc2_ep_disable() which will leave struct udc_ep_config busy flag
set.

When endpoint 0x00 busy flag is left to true, the driver won't allocate
buffer to receive SETUP data which is mandatory in Buffer DMA mode. This
leads to essentially dead device after reconnect, because the device
will not respond to any control transfers.

Solve the issue by modifying backup register value instead of real one
when endpoint is deactivated while core is hibernated.

Signed-off-by: Tomasz Moń <[email protected]>

Author: tmon-nordic

drivers/usb/udc/udc_dwc2.c

@@ -1733,7 +1733,19 @@ static int udc_dwc2_ep_deactivate(const struct device *dev,
 	mem_addr_t dxepctl_reg;
 	uint32_t dxepctl;
 
-	dxepctl_reg = dwc2_get_dxepctl_reg(dev, cfg->addr);
+	if (priv->hibernated) {
+		/* If usbd_disable() is called when core is hibernated, modify
+		 * backup registers instead of real ones.
+		 */
+		if (USB_EP_DIR_IS_OUT(cfg->addr)) {
+			dxepctl_reg = (mem_addr_t)&priv->backup.doepctl[ep_idx];
+		} else {
+			dxepctl_reg = (mem_addr_t)&priv->backup.diepctl[ep_idx];
+		}
+	} else {
+		dxepctl_reg = dwc2_get_dxepctl_reg(dev, cfg->addr);
+	}
+
 	dxepctl = sys_read32(dxepctl_reg);
 
 	if (dxepctl & USB_DWC2_DEPCTL_USBACTEP) {