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 819fdd9b4413b175ccfd493e6b13d48bfff652f9..1b3acb5852a0d369a4e99acc5b95b122a166851c 100644 (file)
--- 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)) {