From 6c79f09fce4dd03f6b623b1d49e1b8a968822f60 Mon Sep 17 00:00:00 2001
From: Thierry Reding <treding@nvidia.com>
Date: Mon, 24 Jun 2019 13:30:24 +0200
Subject: drm/tegra: dpaux: Fix crash if VDD supply is absent
Git-commit: 6c79f09fce4dd03f6b623b1d49e1b8a968822f60
Patch-mainline: v5.5-rc1
References: bsc#1152472

In order to properly make the VDD supply optional, all accesses to the
regulator need to be ignored, because the regulator core doesn't treat
NULL special.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tegra/dpaux.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 819fdd9b4413..1b3acb5852a0 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -505,6 +505,8 @@ static int tegra_dpaux_probe(struct platform_device *pdev)
 
 			return PTR_ERR(dpaux->vdd);
 		}
+
+		dpaux->vdd = NULL;
 	}
 
 	platform_set_drvdata(pdev, dpaux);
@@ -698,13 +700,15 @@ int drm_dp_aux_attach(struct drm_dp_aux *aux, struct tegra_output *output)
 	output->connector.polled = DRM_CONNECTOR_POLL_HPD;
 	dpaux->output = output;
 
-	err = regulator_enable(dpaux->vdd);
-	if (err < 0)
-		return err;
-
 	if (output->panel) {
 		enum drm_connector_status status;
 
+		if (dpaux->vdd) {
+			err = regulator_enable(dpaux->vdd);
+			if (err < 0)
+				return err;
+		}
+
 		timeout = jiffies + msecs_to_jiffies(250);
 
 		while (time_before(jiffies, timeout)) {
@@ -732,13 +736,15 @@ int drm_dp_aux_detach(struct drm_dp_aux *aux)
 
 	disable_irq(dpaux->irq);
 
-	err = regulator_disable(dpaux->vdd);
-	if (err < 0)
-		return err;
-
 	if (dpaux->output->panel) {
 		enum drm_connector_status status;
 
+		if (dpaux->vdd) {
+			err = regulator_disable(dpaux->vdd);
+			if (err < 0)
+				return err;
+		}
+
 		timeout = jiffies + msecs_to_jiffies(250);
 
 		while (time_before(jiffies, timeout)) {
-- 
2.28.0