[Intel-gfx] [PATCH 05/29] drm/i915: prevent NULL pointer exception when using gmbus

[Eugeni Dodonov]

Prevent a NULL pointer exception when we are trying to retrieve EDID data
from non-existent adapter.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c |   30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index f6a9b83..700bd0b 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -389,14 +389,16 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
 {
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 	struct drm_i915_private *dev_priv = connector->dev->dev_private;
-	struct edid *edid;
+	struct edid *edid = NULL;
 	enum drm_connector_status status = connector_status_disconnected;
+	struct i2c_adapter *adapter;
 
 	intel_hdmi->has_hdmi_sink = false;
 	intel_hdmi->has_audio = false;
-	edid = drm_get_edid(connector,
-			    intel_gmbus_get_adapter(dev_priv,
-						    intel_hdmi->ddc_bus));
+
+	adapter = intel_gmbus_get_adapter(dev_priv, intel_hdmi->ddc_bus);
+	if (adapter)
+		edid = drm_get_edid(connector, adapter);
 
 	if (edid) {
 		if (edid->input & DRM_EDID_INPUT_DIGITAL) {
@@ -423,14 +425,17 @@ static int intel_hdmi_get_modes(struct drm_connector *connector)
 {
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 	struct drm_i915_private *dev_priv = connector->dev->dev_private;
+	struct i2c_adapter *adapter;
 
 	/* We should parse the EDID data and find out if it's an HDMI sink so
 	 * we can send audio to it.
 	 */
 
-	return intel_ddc_get_modes(connector,
-				   intel_gmbus_get_adapter(dev_priv,
-							   intel_hdmi->ddc_bus));
+	adapter = intel_gmbus_get_adapter(dev_priv, intel_hdmi->ddc_bus);
+	if (!adapter)
+		return 0;
+
+	return intel_ddc_get_modes(connector, adapter);
 }
 
 static bool
@@ -438,12 +443,15 @@ intel_hdmi_detect_audio(struct drm_connector *connector)
 {
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 	struct drm_i915_private *dev_priv = connector->dev->dev_private;
-	struct edid *edid;
+	struct edid *edid = NULL;
 	bool has_audio = false;
+	struct i2c_adapter *adapter;
+
+	adapter = intel_gmbus_get_adapter(dev_priv, intel_hdmi->ddc_bus);
+
+	if (adapter)
+		edid = drm_get_edid(connector, adapter);
 
-	edid = drm_get_edid(connector,
-			    intel_gmbus_get_adapter(dev_priv,
-						    intel_hdmi->ddc_bus));
 	if (edid) {
 		if (edid->input & DRM_EDID_INPUT_DIGITAL)
 			has_audio = drm_detect_monitor_audio(edid);
-- 
1.7.10