kms: handle output reporting

Reports the different available connectors when opening the KMS vout
window module, with naming like most Wayland compositors and DRM info
tools.

This does not implement hotplug support though.

modules/video_output/kms.c

@@ -182,6 +182,50 @@ static deviceRval SetupDevice(vout_window_t *wnd, drmModeRes const *res,
     return drvSuccess;
 }
 
+static void UpdateOutputs(vout_window_t *wnd)
+{
+    struct vout_window_sys_t *sys = wnd->sys;
+    drmModeRes *modeRes = sys->modeRes;
+
+    msg_Info(wnd, "Updating list of connectors:");
+    for (int c = 0; c < modeRes->count_connectors && sys->crtc == 0; c++)
+    {
+        drmModeConnector *conn =
+            drmModeGetConnector(sys->drm_fd, modeRes->connectors[c]);
+        if (conn == NULL)
+            continue;
+
+        if (conn->connector_type >= ARRAY_SIZE(connector_type_names) ||
+            conn->connection != DRM_MODE_CONNECTED)
+        {
+            drmModeFreeConnector(conn);
+            continue;
+        }
+
+        char name[32];
+        snprintf(name, sizeof name, "%s-%d",
+                 connector_type_names[conn->connector_type],
+                 conn->connector_type_id);
+
+        /* Iterate all available encoders to find CRTC */
+        for (int i = 0; i < conn->count_encoders; i++)
+        {
+            drmModeEncoder *enc =
+                drmModeGetEncoder(sys->drm_fd, conn->encoders[i]);
+
+            size_t crtc_index = sys->crtc;
+            if ((enc->possible_crtcs & (1 << crtc_index)) != 0) {
+
+                drmModeFreeEncoder(enc);
+                vout_window_ReportOutputDevice(wnd, name, name);
+                break;
+            }
+            drmModeFreeEncoder(enc);
+        }
+        drmModeFreeConnector(conn);
+    }
+}
+
 static int WindowEnable(vout_window_t *wnd, const vout_window_cfg_t *cfg)
 {
     struct vout_window_sys_t *sys = wnd->sys;
@@ -190,6 +234,7 @@ static int WindowEnable(vout_window_t *wnd, const vout_window_cfg_t *cfg)
 
     bool found_connector = false;
 
+    // TODO: use kms-connector as a list of connector for clones
     char *connector_request = var_InheritString(wnd, "kms-connector");
     msg_Info(wnd, "Looping over %d resources", modeRes->count_connectors);
     for (int c = 0; c < modeRes->count_connectors && sys->crtc == 0; c++) {
@@ -418,6 +463,8 @@ static int OpenWindow(vout_window_t *wnd)
     wnd->display.drm_fd = sys->drm_fd;
     /* Note: wnd->handle.crtc will be initialized later */
 
+    UpdateOutputs(wnd);
+
     return VLC_SUCCESS;
 error_drm:
     drmDropMaster(sys->drm_fd);