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

1 files changed, 47 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 00e40a26a800..3d48ad1c3682 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/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)
@@ -1306,6 +1327,30 @@ 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
  *
  * content type (HDMI specific):