platform/chrome: cros_ec_typec: Add DP mode check

There are certain transitional situations where the dp_mode field in the
PD_CONTROL response might not be populated with the right DP pin
assignment value yet. Add a check for that to avoid sending an invalid
value to the Type C mode switch.
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210421042108.2002-1-pmalani@chromium.org

drivers/platform/chrome/cros_ec_typec.c

@@ -487,6 +487,11 @@ static int cros_typec_enable_dp(struct cros_typec_data *typec,
 		return -ENOTSUPP;
 	}
 
+	if (!pd_ctrl->dp_mode) {
+		dev_err(typec->dev, "No valid DP mode provided.\n");
+		return -EINVAL;
+	}
+
 	/* Status VDO. */
 	dp_data.status = DP_STATUS_ENABLED;
 	if (port->mux_flags & USB_PD_MUX_HPD_IRQ)