kmssink: add mode setting and base plane rendering

The kmssink assumed that the mode was already set by another application
and used an overlay plane for displaying the frames.

Use the preferred mode of the monitor and render to the base plane if
the crtc does not have a valid mode.

https://bugzilla.gnome.org/show_bug.cgi?id=773473

Signed-off-by: Víctor Manuel Jáquez Leal <vjaquez@igalia.com>

sys/kms/gstkmssink.c

@@ -137,6 +137,7 @@ find_crtc_for_connector (int fd, drmModeRes * res, drmModeConnector * conn,
   int crtc_id;
   drmModeEncoder *enc;
   drmModeCrtc *crtc;
+  guint32 crtcs_for_connector = 0;
 
   crtc_id = -1;
   for (i = 0; i < res->count_encoders; i++) {
@@ -151,6 +152,18 @@ find_crtc_for_connector (int fd, drmModeRes * res, drmModeConnector * conn,
     }
   }
 
+  /* If no active crtc was found, pick the first possible crtc */
+  if (crtc_id == -1) {
+    for (i = 0; i < conn->count_encoders; i++) {
+      enc = drmModeGetEncoder (fd, conn->encoders[i]);
+      crtcs_for_connector |= enc->possible_crtcs;
+      drmModeFreeEncoder (enc);
+    }
+
+    if (crtcs_for_connector != 0)
+      crtc_id = res->crtcs[ffs (crtcs_for_connector) - 1];
+  }
+
   if (crtc_id == -1)
     return NULL;
 
@@ -241,6 +254,10 @@ find_main_monitor (int fd, drmModeRes * res)
   if (!conn)
     conn = find_first_used_connector (fd, res);
 
+  /* if no connector is used, grab the first one */
+  if (!conn)
+    conn = drmModeGetConnector (fd, res->connectors[0]);
+
   return conn;
 }
 
@@ -302,6 +319,51 @@ get_drm_caps (GstKMSSink * self)
   return TRUE;
 }
 
+static gboolean
+configure_mode_setting (GstKMSSink * self, guint32 fb_id)
+{
+  gboolean ret;
+  drmModeConnector *conn;
+  int err;
+
+  ret = FALSE;
+  conn = NULL;
+
+  if (self->conn_id < 0)
+    goto bail;
+
+  GST_INFO_OBJECT (self, "configuring mode setting");
+
+  conn = drmModeGetConnector (self->fd, self->conn_id);
+  if (!conn)
+    goto connector_failed;
+
+  err = drmModeSetCrtc (self->fd, self->crtc_id, fb_id, 0, 0,
+      (uint32_t *) & self->conn_id, 1, &conn->modes[0]);
+  if (err)
+    goto modesetting_failed;
+
+  ret = TRUE;
+
+bail:
+  if (conn)
+    drmModeFreeConnector (conn);
+
+  return ret;
+
+  /* ERRORS */
+connector_failed:
+  {
+    GST_ERROR_OBJECT (self, "Could not find a valid monitor connector");
+    goto bail;
+  }
+modesetting_failed:
+  {
+    GST_ERROR_OBJECT (self, "Failed to set mode: %s", strerror (errno));
+    goto bail;
+  }
+}
+
 static gboolean
 ensure_allowed_caps (GstKMSSink * self, drmModePlane * plane, drmModeRes * res)
 {
@@ -391,6 +453,12 @@ gst_kms_sink_start (GstBaseSink * bsink)
   if (!crtc)
     goto crtc_failed;
 
+  if (!crtc->mode_valid) {
+    GST_DEBUG_OBJECT (self, "crtc has no valid mode: enabling modesetting");
+    self->modesetting_enabled = TRUE;
+    universal_planes = TRUE;
+  }
+
 retry_find_plane:
   if (universal_planes &&
       drmSetClientCap (self->fd, DRM_CLIENT_CAP_UNIVERSAL_PLANES, 1))
@@ -807,7 +875,7 @@ gst_kms_sink_sync (GstKMSSink * self)
     vbl.request.type |= self->pipe << DRM_VBLANK_HIGH_CRTC_SHIFT;
 
   waiting = TRUE;
-  if (!self->has_async_page_flip) {
+  if (!self->has_async_page_flip && !self->modesetting_enabled) {
     ret = drmWaitVBlank (self->fd, &vbl);
     if (ret)
       goto vblank_failed;
@@ -1038,6 +1106,7 @@ error_map_src_buffer:
 static GstFlowReturn
 gst_kms_sink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
 {
+  static gboolean setup = FALSE;
   gint ret;
   GstBuffer *buffer;
   guint32 fb_id;
@@ -1061,6 +1130,22 @@ gst_kms_sink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
 
   GST_TRACE_OBJECT (self, "displaying fb %d", fb_id);
 
+  if (self->modesetting_enabled) {
+    /* Use the current buffer object for configuring the mode, if the mode is
+     * not configured. Preferably the display mode should be set when
+     * configuring the pipeline (during set_caps), but we do not have a buffer
+     * object at that time. */
+    if (!setup) {
+      ret = configure_mode_setting (self, fb_id);
+      if (!ret)
+        goto modesetting_failed;
+      setup = TRUE;
+    }
+
+    self->buffer_id = fb_id;
+    goto sync_frame;
+  }
+
   if ((crop = gst_buffer_get_video_crop_meta (buffer))) {
     GstVideoInfo vinfo = self->vinfo;
     vinfo.width = crop->width;
@@ -1100,6 +1185,7 @@ gst_kms_sink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
   if (ret)
     goto set_plane_failed;
 
+sync_frame:
   /* Wait for the previous frame to complete redraw */
   if (!gst_kms_sink_sync (self))
     goto bail;
@@ -1118,6 +1204,11 @@ buffer_invalid:
     GST_ERROR_OBJECT (self, "invalid buffer: it doesn't have a fb id");
     goto bail;
   }
+modesetting_failed:
+  {
+    GST_ERROR_OBJECT (self, "failed to configure display mode");
+    goto bail;
+  }
 set_plane_failed:
   {
     GST_DEBUG_OBJECT (self, "result = { %d, %d, %d, %d} / "

sys/kms/gstkmssink.h

@@ -62,6 +62,8 @@ struct _GstKMSSink {
   gboolean has_prime_import;
   gboolean has_async_page_flip;
 
+  gboolean modesetting_enabled;
+
   GstVideoInfo vinfo;
   GstCaps *allowed_caps;
   GstBufferPool *pool;