drm/tegra: sor: Avoid timeouts on unplug events

When the SOR is disabled in DP mode as part of an unplug event, do not
attempt to power the DP link down. Powering down the link requires the
DPAUX to transmit AUX messages which only works if there's a connected
sink.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/sor.c

@@ -2663,9 +2663,16 @@ static void tegra_sor_dp_disable(struct drm_encoder *encoder)
 	if (output->panel)
 		drm_panel_disable(output->panel);
 
-	err = drm_dp_link_power_down(sor->aux, &sor->link);
-	if (err < 0)
-		dev_err(sor->dev, "failed to power down link: %d\n", err);
+	/*
+	 * Do not attempt to power down a DP link if we're not connected since
+	 * the AUX transactions would just be timing out.
+	 */
+	if (output->connector.status != connector_status_disconnected) {
+		err = drm_dp_link_power_down(sor->aux, &sor->link);
+		if (err < 0)
+			dev_err(sor->dev, "failed to power down link: %d\n",
+				err);
+	}
 
 	err = tegra_sor_detach(sor);
 	if (err < 0)