[PATCH 4/4] drm/i915: Determine DP++ type 1 DVI adaptor presence based on VBT

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

DP dual mode type 1 DVI adaptors aren't required to implement any
registers, so it's a bit hard to detect them. The best way would
be to check the state of the CONFIG1 pin, but we have no way to
do that. So as a last resort, check the VBT to see if the HDMI
port is in fact a dual mode capable DP port.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_bios.h |  3 +++
 drivers/gpu/drm/i915/intel_dp.c   | 28 ++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h  |  1 +
 drivers/gpu/drm/i915/intel_hdmi.c | 23 +++++++++++++++++++++--
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
index 350d4e0f75a4..50d1659efe47 100644
--- a/drivers/gpu/drm/i915/intel_bios.h
+++ b/drivers/gpu/drm/i915/intel_bios.h
@@ -730,6 +730,7 @@ struct bdb_psr {
 #define	 DEVICE_TYPE_INT_TV	0x1009
 #define	 DEVICE_TYPE_HDMI	0x60D2
 #define	 DEVICE_TYPE_DP		0x68C6
+#define	 DEVICE_TYPE_DP_DUAL_MODE	0x60D6
 #define	 DEVICE_TYPE_eDP	0x78C6
 
 #define  DEVICE_TYPE_CLASS_EXTENSION	(1 << 15)
@@ -764,6 +765,8 @@ struct bdb_psr {
 	 DEVICE_TYPE_DISPLAYPORT_OUTPUT | \
 	 DEVICE_TYPE_ANALOG_OUTPUT)
 
+#define DEVICE_TYPE_DP_DUAL_MODE_BITS ~DEVICE_TYPE_NOT_HDMI_OUTPUT
+
 /* define the DVO port for HDMI output type */
 #define		DVO_B		1
 #define		DVO_C		2
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index cbc06596659a..f3edacf517ac 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5104,6 +5104,34 @@ bool intel_dp_is_edp(struct drm_device *dev, enum port port)
 	return false;
 }
 
+bool intel_dp_is_dual_mode(struct drm_i915_private *dev_priv, enum port port)
+{
+	const union child_device_config *p_child;
+	int i;
+	static const short port_mapping[] = {
+		[PORT_B] = DVO_PORT_DPB,
+		[PORT_C] = DVO_PORT_DPC,
+		[PORT_D] = DVO_PORT_DPD,
+		[PORT_E] = DVO_PORT_DPE,
+	};
+
+	if (port == PORT_A || port >= ARRAY_SIZE(port_mapping))
+		return false;
+
+	if (!dev_priv->vbt.child_dev_num)
+		return false;
+
+	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
+		p_child = &dev_priv->vbt.child_dev[i];
+
+		if (p_child->common.dvo_port == port_mapping[port] &&
+		    (p_child->common.device_type & DEVICE_TYPE_DP_DUAL_MODE_BITS) ==
+		    (DEVICE_TYPE_DP_DUAL_MODE & DEVICE_TYPE_DP_DUAL_MODE_BITS))
+			return true;
+	}
+	return false;
+}
+
 void
 intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connector)
 {
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3ca29a181e64..c7d1ea4dbe42 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1248,6 +1248,7 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc);
 bool intel_dp_compute_config(struct intel_encoder *encoder,
 			     struct intel_crtc_state *pipe_config);
 bool intel_dp_is_edp(struct drm_device *dev, enum port port);
+bool intel_dp_is_dual_mode(struct drm_i915_private *dev_priv, enum port port);
 enum irqreturn intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port,
 				  bool long_hpd);
 void intel_edp_backlight_on(struct intel_dp *intel_dp);
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 660a65f48fd8..1476f3afb7e2 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1390,14 +1390,33 @@ intel_hdmi_unset_edid(struct drm_connector *connector)
 }
 
 static void
-intel_hdmi_dp_dual_mode_detect(struct drm_connector *connector)
+intel_hdmi_dp_dual_mode_detect(struct drm_connector *connector, bool has_edid)
 {
 	struct drm_i915_private *dev_priv = to_i915(connector->dev);
 	struct intel_hdmi *hdmi = intel_attached_hdmi(connector);
+	enum port port = hdmi_to_dig_port(hdmi)->port;
 	struct i2c_adapter *adapter =
 		intel_gmbus_get_adapter(dev_priv, hdmi->ddc_bus);
 	enum drm_dp_dual_mode_type type = drm_dp_dual_mode_detect(adapter);
 
+	/*
+	 * Type 1 DVI adaptors are not required to implement any
+	 * registers, so we can't always detect their presence.
+	 * Ideally we should be able to check the state of the
+	 * CONFIG1 pin, but no such luck on our hardware.
+	 *
+	 * The only method left to us is to check the VBT to see
+	 * if the port is a dual mode capable DP port. But let's
+	 * only do that when we sucesfully read the EDID, to avoid
+	 * confusing log messages about DP dual mode adaptors when
+	 * there's nothing connected to the port.
+	 */
+	if (type == DRM_DP_DUAL_MODE_NONE && has_edid &&
+	    intel_dp_is_dual_mode(dev_priv, port)) {
+		DRM_DEBUG_KMS("Assuming DP dual mode adaptor presence based on VBT\n");
+		type = DRM_DP_DUAL_MODE_TYPE1_DVI;
+	}
+
 	if (type == DRM_DP_DUAL_MODE_NONE)
 		return;
 
@@ -1441,7 +1460,7 @@ intel_hdmi_set_edid(struct drm_connector *connector, bool force)
 				    intel_gmbus_get_adapter(dev_priv,
 				    intel_hdmi->ddc_bus));
 
-		intel_hdmi_dp_dual_mode_detect(connector);
+		intel_hdmi_dp_dual_mode_detect(connector, edid != NULL);
 
 		intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
 	}
-- 
2.4.10