From: Thierry Reding <treding@nvidia.com>
Date: Mon, 24 Jun 2019 11:30:24 +0000 (+0200)
Subject: drm/tegra: dpaux: Fix crash if VDD supply is absent
X-Git-Tag: v5.5-rc1~128^2~20^2~47
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=6c79f09fce4dd03f6b623b1d49e1b8a968822f60;p=linux.git

drm/tegra: dpaux: Fix crash if VDD supply is absent

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>
---

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)) {