drm: report dp downstream port type as a subconnector property

Currently, downstream port type is only reported in debugfs. This
information should be considered important since it reflects the actual
physical connector type. Some userspace (e.g. window compositors)
may want to show this info to a user.

The 'subconnector' property is already utilized for DVI-I and TV-out for
reporting connector subtype.

The initial motivation for this feature came from i2c test [1].
It is supposed to be skipped on VGA connectors, but it cannot
detect VGA over DP and fails instead.

v2:
 - Ville: utilized drm_dp_is_branch()
 - Ville: implement DP 1.0 downstream type info
 - Replaced create_dp_properties with add_dp_subconnector_property
 - Added dp_set_subconnector_property helper

v4:
 - Ville: add DP1.0 best assumption about subconnector
 - Ville: assume DVI is DVI-D
 - Ville: reuse Writeback enum value for Virtual subconnector
 - Renamed #defines: HDMI -> HDMIA, DP -> DisplayPort

v5: rebase

v6:
 - Jani Nikula: renamed a function name
 - Jani Nikula: addressed the issues with documentation

[1]: https://bugs.freedesktop.org/show_bug.cgi?id=104097

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Jeevan B <jeevan.b@intel.com>
Signed-off-by: Oleg Vasilev <oleg.vasilev@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1587732655-17544-1-git-send-email-jeevan.b@intel.com

drivers/gpu/drm/drm_connector.c

@@ -850,7 +850,7 @@ static const struct drm_prop_enum_list drm_dvi_i_select_enum_list[] = {
 DRM_ENUM_NAME_FN(drm_get_dvi_i_select_name, drm_dvi_i_select_enum_list)
 
 static const struct drm_prop_enum_list drm_dvi_i_subconnector_enum_list[] = {
-	{ DRM_MODE_SUBCONNECTOR_Unknown,   "Unknown"   }, /* DVI-I and TV-out */
+	{ DRM_MODE_SUBCONNECTOR_Unknown,   "Unknown"   }, /* DVI-I, TV-out and DP */
 	{ DRM_MODE_SUBCONNECTOR_DVID,      "DVI-D"     }, /* DVI-I  */
 	{ DRM_MODE_SUBCONNECTOR_DVIA,      "DVI-A"     }, /* DVI-I  */
 };
@@ -867,7 +867,7 @@ static const struct drm_prop_enum_list drm_tv_select_enum_list[] = {
 DRM_ENUM_NAME_FN(drm_get_tv_select_name, drm_tv_select_enum_list)
 
 static const struct drm_prop_enum_list drm_tv_subconnector_enum_list[] = {
-	{ DRM_MODE_SUBCONNECTOR_Unknown,   "Unknown"   }, /* DVI-I and TV-out */
+	{ DRM_MODE_SUBCONNECTOR_Unknown,   "Unknown"   }, /* DVI-I, TV-out and DP */
 	{ DRM_MODE_SUBCONNECTOR_Composite, "Composite" }, /* TV-out */
 	{ DRM_MODE_SUBCONNECTOR_SVIDEO,    "SVIDEO"    }, /* TV-out */
 	{ DRM_MODE_SUBCONNECTOR_Component, "Component" }, /* TV-out */
@@ -876,6 +876,19 @@ static const struct drm_prop_enum_list drm_tv_subconnector_enum_list[] = {
 DRM_ENUM_NAME_FN(drm_get_tv_subconnector_name,
 		 drm_tv_subconnector_enum_list)
 
+static const struct drm_prop_enum_list drm_dp_subconnector_enum_list[] = {
+	{ DRM_MODE_SUBCONNECTOR_Unknown,     "Unknown"   }, /* DVI-I, TV-out and DP */
+	{ DRM_MODE_SUBCONNECTOR_VGA,	     "VGA"       }, /* DP */
+	{ DRM_MODE_SUBCONNECTOR_DVID,	     "DVI-D"     }, /* DP */
+	{ DRM_MODE_SUBCONNECTOR_HDMIA,	     "HDMI"      }, /* DP */
+	{ DRM_MODE_SUBCONNECTOR_DisplayPort, "DP"        }, /* DP */
+	{ DRM_MODE_SUBCONNECTOR_Wireless,    "Wireless"  }, /* DP */
+	{ DRM_MODE_SUBCONNECTOR_Native,	     "Native"    }, /* DP */
+};
+
+DRM_ENUM_NAME_FN(drm_get_dp_subconnector_name,
+		 drm_dp_subconnector_enum_list)
+
 static const struct drm_prop_enum_list hdmi_colorspaces[] = {
 	/* For Default case, driver will set the colorspace */
 	{ DRM_MODE_COLORIMETRY_DEFAULT, "Default" },
@@ -1217,6 +1230,14 @@ static const struct drm_prop_enum_list dp_colorspaces[] = {
  *	can also expose this property to external outputs, in which case they
  *	must support "None", which should be the default (since external screens
  *	have a built-in scaler).
+ *
+ * subconnector:
+ *	This property is used by DVI-I, TVout and DisplayPort to indicate different
+ *	connector subtypes. Enum values more or less match with those from main
+ *	connector types.
+ *	For DVI-I and TVout there is also a matching property "select subconnector"
+ *	allowing to switch between signal types.
+ *	DP subconnector corresponds to a downstream port.
  */
 
 int drm_connector_create_standard_properties(struct drm_device *dev)
@@ -1305,6 +1326,30 @@ int drm_mode_create_dvi_i_properties(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_mode_create_dvi_i_properties);
 
+/**
+ * drm_connector_attach_dp_subconnector_property - create subconnector property for DP
+ * @connector: drm_connector to attach property
+ *
+ * Called by a driver when DP connector is created.
+ */
+void drm_connector_attach_dp_subconnector_property(struct drm_connector *connector)
+{
+	struct drm_mode_config *mode_config = &connector->dev->mode_config;
+
+	if (!mode_config->dp_subconnector_property)
+		mode_config->dp_subconnector_property =
+			drm_property_create_enum(connector->dev,
+				DRM_MODE_PROP_IMMUTABLE,
+				"subconnector",
+				drm_dp_subconnector_enum_list,
+				ARRAY_SIZE(drm_dp_subconnector_enum_list));
+
+	drm_object_attach_property(&connector->base,
+				   mode_config->dp_subconnector_property,
+				   DRM_MODE_SUBCONNECTOR_Unknown);
+}
+EXPORT_SYMBOL(drm_connector_attach_dp_subconnector_property);
+
 /**
  * DOC: HDMI connector properties
  *

drivers/gpu/drm/drm_dp_helper.c

@@ -597,6 +597,77 @@ void drm_dp_downstream_debug(struct seq_file *m,
 }
 EXPORT_SYMBOL(drm_dp_downstream_debug);
 
+/**
+ * drm_dp_subconnector_type() - get DP branch device type
+ *
+ */
+enum drm_mode_subconnector
+drm_dp_subconnector_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+			 const u8 port_cap[4])
+{
+	int type;
+	if (!drm_dp_is_branch(dpcd))
+		return DRM_MODE_SUBCONNECTOR_Native;
+	/* DP 1.0 approach */
+	if (dpcd[DP_DPCD_REV] == DP_DPCD_REV_10) {
+		type = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+		       DP_DWN_STRM_PORT_TYPE_MASK;
+
+		switch (type) {
+		case DP_DWN_STRM_PORT_TYPE_TMDS:
+			/* Can be HDMI or DVI-D, DVI-D is a safer option */
+			return DRM_MODE_SUBCONNECTOR_DVID;
+		case DP_DWN_STRM_PORT_TYPE_ANALOG:
+			/* Can be VGA or DVI-A, VGA is more popular */
+			return DRM_MODE_SUBCONNECTOR_VGA;
+		case DP_DWN_STRM_PORT_TYPE_DP:
+			return DRM_MODE_SUBCONNECTOR_DisplayPort;
+		case DP_DWN_STRM_PORT_TYPE_OTHER:
+		default:
+			return DRM_MODE_SUBCONNECTOR_Unknown;
+		}
+	}
+	type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
+
+	switch (type) {
+	case DP_DS_PORT_TYPE_DP:
+	case DP_DS_PORT_TYPE_DP_DUALMODE:
+		return DRM_MODE_SUBCONNECTOR_DisplayPort;
+	case DP_DS_PORT_TYPE_VGA:
+		return DRM_MODE_SUBCONNECTOR_VGA;
+	case DP_DS_PORT_TYPE_DVI:
+		return DRM_MODE_SUBCONNECTOR_DVID;
+	case DP_DS_PORT_TYPE_HDMI:
+		return DRM_MODE_SUBCONNECTOR_HDMIA;
+	case DP_DS_PORT_TYPE_WIRELESS:
+		return DRM_MODE_SUBCONNECTOR_Wireless;
+	case DP_DS_PORT_TYPE_NON_EDID:
+	default:
+		return DRM_MODE_SUBCONNECTOR_Unknown;
+	}
+}
+EXPORT_SYMBOL(drm_dp_subconnector_type);
+
+/**
+ * drm_mode_set_dp_subconnector_property - set subconnector for DP connector
+ *
+ * Called by a driver on every detect event.
+ */
+void drm_dp_set_subconnector_property(struct drm_connector *connector,
+				      enum drm_connector_status status,
+				      const u8 *dpcd,
+				      const u8 port_cap[4])
+{
+	enum drm_mode_subconnector subconnector = DRM_MODE_SUBCONNECTOR_Unknown;
+
+	if (status == connector_status_connected)
+		subconnector = drm_dp_subconnector_type(dpcd, port_cap);
+	drm_object_property_set_value(&connector->base,
+			connector->dev->mode_config.dp_subconnector_property,
+			subconnector);
+}
+EXPORT_SYMBOL(drm_dp_set_subconnector_property);
+
 /*
  * I2C-over-AUX implementation
  */

include/drm/drm_connector.h

@@ -1604,10 +1604,13 @@ const char *drm_get_dvi_i_subconnector_name(int val);
 const char *drm_get_dvi_i_select_name(int val);
 const char *drm_get_tv_subconnector_name(int val);
 const char *drm_get_tv_select_name(int val);
+const char *drm_get_dp_subconnector_name(int val);
 const char *drm_get_content_protection_name(int val);
 const char *drm_get_hdcp_content_type_name(int val);
 
 int drm_mode_create_dvi_i_properties(struct drm_device *dev);
+void drm_connector_attach_dp_subconnector_property(struct drm_connector *connector);
+
 int drm_mode_create_tv_margin_properties(struct drm_device *dev);
 int drm_mode_create_tv_properties(struct drm_device *dev,
 				  unsigned int num_modes,

include/drm/drm_dp_helper.h

@@ -26,6 +26,7 @@
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/types.h>
+#include <drm/drm_connector.h>
 
 /*
  * Unless otherwise noted, all values are from the DP 1.1a spec.  Note that
@@ -1619,6 +1620,13 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
 void drm_dp_downstream_debug(struct seq_file *m, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 			     const u8 port_cap[4], struct drm_dp_aux *aux);
+enum drm_mode_subconnector
+drm_dp_subconnector_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+			 const u8 port_cap[4]);
+void drm_dp_set_subconnector_property(struct drm_connector *connector,
+				      enum drm_connector_status status,
+				      const u8 *dpcd,
+				      const u8 port_cap[4]);
 
 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);

include/drm/drm_mode_config.h

@@ -680,6 +680,12 @@ struct drm_mode_config {
 	 */
 	struct drm_property *dvi_i_select_subconnector_property;
 
+	/**
+	 * @dp_subconnector_property: Optional DP property to differentiate
+	 * between different DP downstream port types.
+	 */
+	struct drm_property *dp_subconnector_property;
+
 	/**
 	 * @tv_subconnector_property: Optional TV property to differentiate
 	 * between different TV connector types.

include/uapi/drm/drm_mode.h

@@ -332,14 +332,19 @@ struct drm_mode_get_encoder {
 /* This is for connectors with multiple signal types. */
 /* Try to match DRM_MODE_CONNECTOR_X as closely as possible. */
 enum drm_mode_subconnector {
-	DRM_MODE_SUBCONNECTOR_Automatic = 0,
-	DRM_MODE_SUBCONNECTOR_Unknown = 0,
-	DRM_MODE_SUBCONNECTOR_DVID = 3,
-	DRM_MODE_SUBCONNECTOR_DVIA = 4,
-	DRM_MODE_SUBCONNECTOR_Composite = 5,
-	DRM_MODE_SUBCONNECTOR_SVIDEO = 6,
-	DRM_MODE_SUBCONNECTOR_Component = 8,
-	DRM_MODE_SUBCONNECTOR_SCART = 9,
+	DRM_MODE_SUBCONNECTOR_Automatic   = 0,  /* DVI-I, TV     */
+	DRM_MODE_SUBCONNECTOR_Unknown     = 0,  /* DVI-I, TV, DP */
+	DRM_MODE_SUBCONNECTOR_VGA	  = 1,  /*            DP */
+	DRM_MODE_SUBCONNECTOR_DVID	  = 3,  /* DVI-I      DP */
+	DRM_MODE_SUBCONNECTOR_DVIA	  = 4,  /* DVI-I         */
+	DRM_MODE_SUBCONNECTOR_Composite   = 5,  /*        TV     */
+	DRM_MODE_SUBCONNECTOR_SVIDEO	  = 6,  /*        TV     */
+	DRM_MODE_SUBCONNECTOR_Component   = 8,  /*        TV     */
+	DRM_MODE_SUBCONNECTOR_SCART	  = 9,  /*        TV     */
+	DRM_MODE_SUBCONNECTOR_DisplayPort = 10, /*            DP */
+	DRM_MODE_SUBCONNECTOR_HDMIA       = 11, /*            DP */
+	DRM_MODE_SUBCONNECTOR_Native      = 15, /*            DP */
+	DRM_MODE_SUBCONNECTOR_Wireless    = 18, /*            DP */
 };
 
 #define DRM_MODE_CONNECTOR_Unknown	0