native: Implement DRM-based crtc rotation

We can know the rotation modes supported by the driver, so
export these as our supported modes, and ensure these modes
are honored on the CRTC primary plane upon apply_configuration().

It is worth noting however that not all hardware will be
capable of supporting all rotation modes (in fact, most of
them won't). A driver independent solution should be in
place to back up the rotation modes unsupported by the
drivers, so this is still a partial solution.

The cursor renderer has also been changed to default to
software-based rendering anytime the cursor enters a
rotated CRTC. Another solution would be actually rotating
the DRM cursor planes, but then it requires applying rotation on
these per-CRTC, and actually transforming the pointer position by
the output matrix. This brings marginal gains, so we use the
"sw" rendered cursor, which will be transformed together with
the primary plane.

https://bugzilla.gnome.org/show_bug.cgi?id=745079

src/backends/native/meta-cursor-renderer-native.c

@@ -273,6 +273,32 @@ has_valid_cursor_sprite_gbm_bo (MetaCursorSprite *cursor_sprite)
   return FALSE;
 }
 
+static gboolean
+cursor_over_transformed_crtc (MetaCursorRenderer *renderer,
+                              MetaCursorSprite   *cursor_sprite)
+{
+  MetaMonitorManager *monitors;
+  MetaCRTC *crtcs;
+  unsigned int i, n_crtcs;
+  MetaRectangle rect;
+
+  monitors = meta_monitor_manager_get ();
+  meta_monitor_manager_get_resources (monitors, NULL, NULL,
+                                      &crtcs, &n_crtcs, NULL, NULL);
+  rect = meta_cursor_renderer_calculate_rect (renderer, cursor_sprite);
+
+  for (i = 0; i < n_crtcs; i++)
+    {
+      if (!meta_rectangle_overlap (&rect, &crtcs[i].rect))
+        continue;
+
+      if (crtcs[i].transform != META_MONITOR_TRANSFORM_NORMAL)
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
 static gboolean
 should_have_hw_cursor (MetaCursorRenderer *renderer,
                        MetaCursorSprite   *cursor_sprite)
@@ -282,6 +308,9 @@ should_have_hw_cursor (MetaCursorRenderer *renderer,
   if (!cursor_sprite)
     return FALSE;
 
+  if (cursor_over_transformed_crtc (renderer, cursor_sprite))
+    return FALSE;
+
   texture = meta_cursor_sprite_get_cogl_texture (cursor_sprite);
   if (!texture)
     return FALSE;