From 68a2ebb54da4dfa2cc3a2239d2e2dfeec2c5e522 Mon Sep 17 00:00:00 2001
From: Thierry Reding <treding@nvidia.com>
Date: Thu, 25 Jul 2019 15:41:36 +0200
Subject: drm/tegra: sor: Avoid timeouts on unplug events
Git-commit: 68a2ebb54da4dfa2cc3a2239d2e2dfeec2c5e522
Patch-mainline: v5.5-rc1
References: bsc#1152472

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>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tegra/sor.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c
index 63831c37ad35..b81e6d39aa32 100644
--- a/drivers/gpu/drm/tegra/sor.c
+++ b/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)
-- 
2.28.0