xf86drmMode: introduce drmModeGetConnectorTypeName

User-space often needs to print the name of a connector type.
When a new connector type is added, all user-space programs need
to be updated to support the new connector type.

Expose a function to get a connector type name in libdrm.

The names are taken from the kernel [1].

[1]: https://cgit.freedesktop.org/drm/drm/tree/drivers/gpu/drm/drm_connector.c?h=4fc8cb47fcfdc93e274a1291757e478df4f9c39b#n83

Signed-off-by: Simon Ser <contact@emersion.fr>

core-symbols.txt

@@ -126,6 +126,7 @@ drmModeFreePropertyBlob
 drmModeFreeResources
 drmModeGetConnector
 drmModeGetConnectorCurrent
+drmModeGetConnectorTypeName
 drmModeGetCrtc
 drmModeGetEncoder
 drmModeGetFB

xf86drmMode.c

@@ -1747,3 +1747,56 @@ drm_public void drmModeFreeFB2(drmModeFB2Ptr ptr)
 {
 	drmFree(ptr);
 }
+
+drm_public const char *
+drmModeGetConnectorTypeName(uint32_t connector_type)
+{
+	/* Keep the strings in sync with the kernel's drm_connector_enum_list in
+	 * drm_connector.c. */
+	switch (connector_type) {
+	case DRM_MODE_CONNECTOR_Unknown:
+		return "Unknown";
+	case DRM_MODE_CONNECTOR_VGA:
+		return "VGA";
+	case DRM_MODE_CONNECTOR_DVII:
+		return "DVI-I";
+	case DRM_MODE_CONNECTOR_DVID:
+		return "DVI-D";
+	case DRM_MODE_CONNECTOR_DVIA:
+		return "DVI-A";
+	case DRM_MODE_CONNECTOR_Composite:
+		return "Composite";
+	case DRM_MODE_CONNECTOR_SVIDEO:
+		return "SVIDEO";
+	case DRM_MODE_CONNECTOR_LVDS:
+		return "LVDS";
+	case DRM_MODE_CONNECTOR_Component:
+		return "Component";
+	case DRM_MODE_CONNECTOR_9PinDIN:
+		return "DIN";
+	case DRM_MODE_CONNECTOR_DisplayPort:
+		return "DP";
+	case DRM_MODE_CONNECTOR_HDMIA:
+		return "HDMI-A";
+	case DRM_MODE_CONNECTOR_HDMIB:
+		return "HDMI-B";
+	case DRM_MODE_CONNECTOR_TV:
+		return "TV";
+	case DRM_MODE_CONNECTOR_eDP:
+		return "eDP";
+	case DRM_MODE_CONNECTOR_VIRTUAL:
+		return "Virtual";
+	case DRM_MODE_CONNECTOR_DSI:
+		return "DSI";
+	case DRM_MODE_CONNECTOR_DPI:
+		return "DPI";
+	case DRM_MODE_CONNECTOR_WRITEBACK:
+		return "Writeback";
+	case DRM_MODE_CONNECTOR_SPI:
+		return "SPI";
+	case DRM_MODE_CONNECTOR_USB:
+		return "USB";
+	default:
+		return NULL;
+	}
+}

xf86drmMode.h

@@ -475,6 +475,15 @@ extern drmModeObjectListPtr drmModeGetLease(int fd);
 
 extern int drmModeRevokeLease(int fd, uint32_t lessee_id);
 
+/**
+ * Get a string describing a connector type.
+ *
+ * NULL is returned if the connector type is unsupported. Callers should handle
+ * this gracefully, e.g. by falling back to "Unknown" or printing the raw value.
+ */
+extern const char *
+drmModeGetConnectorTypeName(uint32_t connector_type);
+
 #if defined(__cplusplus)
 }
 #endif