[PATCH 3/3] drm/i915: don't init DP or HDMI when not supported by DDI port

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

There's no reason to init a DP connector if the encoder just supports
HDMI: we'll just waste hundreds and hundreds of cycles trying to do DP
AUX transactions to detect if there's something there. Same goes for a
DP connector that doesn't support HDMI, but I'm not sure these
actually exist.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h   |  3 +++
 drivers/gpu/drm/i915/intel_bios.c | 13 ++++++++++++-
 drivers/gpu/drm/i915/intel_ddi.c  | 30 ++++++++++++++++++++++--------
 3 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 645dd74..8720f31 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1041,6 +1041,9 @@ enum modeset_restore {
 
 struct ddi_vbt_port_info {
 	uint8_t hdmi_level_shift;
+	bool supports_dvi;
+	bool supports_hdmi;
+	bool supports_dp;
 };
 
 struct intel_vbt_data {
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 4003dbf..cd823b9 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -608,6 +608,10 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
 	is_hdmi = is_dvi && (child->common.device_type & (1 << 11)) == 0;
 	is_edp = is_dp && (child->common.device_type & (1 << 12));
 
+	info->supports_dvi = is_dvi;
+	info->supports_hdmi = is_hdmi;
+	info->supports_dp = is_dp;
+
 	DRM_DEBUG_KMS("Port %c VBT info: DP:%d HDMI:%d DVI:%d EDP:%d CRT:%d\n",
 		      port_name(port), is_dp, is_hdmi, is_dvi, is_edp, is_crt);
 
@@ -762,8 +766,15 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 		enum port port;
 
 		for (port = PORT_A; port <= PORT_E; port++) {
+			struct ddi_vbt_port_info *info =
+				&dev_priv->vbt.ddi_port_info[port];
+
 			/* Recommended BSpec default: 800mV 0dB. */
-			dev_priv->vbt.ddi_port_info[port].hdmi_level_shift = 6;
+			info->hdmi_level_shift = 6;
+
+			info->supports_dvi = (port != PORT_A && port != PORT_E);
+			info->supports_hdmi = info->supports_dvi;
+			info->supports_dp = (port != PORT_E);
 		}
 	}
 
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index ece226d..d344977 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1325,6 +1325,17 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
 	struct drm_encoder *encoder;
 	struct intel_connector *hdmi_connector = NULL;
 	struct intel_connector *dp_connector = NULL;
+	bool init_hdmi, init_dp;
+
+	init_hdmi = (dev_priv->vbt.ddi_port_info[port].supports_dvi ||
+		     dev_priv->vbt.ddi_port_info[port].supports_hdmi);
+	init_dp = dev_priv->vbt.ddi_port_info[port].supports_dp;
+	if (!init_dp && !init_hdmi) {
+		DRM_ERROR("VBT says port %c is not DVI/HDMI/DP compatible\n",
+			  port_name(port));
+		init_hdmi = true;
+		init_dp = true;
+	}
 
 	intel_dig_port = kzalloc(sizeof(struct intel_digital_port), GFP_KERNEL);
 	if (!intel_dig_port)
@@ -1362,19 +1373,22 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
 	intel_encoder->cloneable = false;
 	intel_encoder->hot_plug = intel_ddi_hot_plug;
 
-	if (!intel_dp_init_connector(intel_dig_port, dp_connector)) {
-		drm_encoder_cleanup(encoder);
-		kfree(intel_dig_port);
-		kfree(dp_connector);
-		return;
+	if (init_dp) {
+		if (!intel_dp_init_connector(intel_dig_port, dp_connector)) {
+			drm_encoder_cleanup(encoder);
+			kfree(intel_dig_port);
+			kfree(dp_connector);
+			return;
+		}
 	}
 
-	if (intel_encoder->type != INTEL_OUTPUT_EDP) {
+	/* In theory we don't need the encoder->type check, but leave it just in
+	 * case we have some really bad VBTs... */
+	if (intel_encoder->type != INTEL_OUTPUT_EDP && init_hdmi) {
 		hdmi_connector = kzalloc(sizeof(struct intel_connector),
 					 GFP_KERNEL);
-		if (!hdmi_connector) {
+		if (!hdmi_connector)
 			return;
-		}
 
 		intel_dig_port->hdmi.hdmi_reg = DDI_BUF_CTL(port);
 		intel_hdmi_init_connector(intel_dig_port, hdmi_connector);
-- 
1.8.1.2