drm/fb: handle tiled connectors better

We don't want tile 0,0 to artificially constrain the size of the legacy
fbdev device.  Instead when reducing fb_size to be the minimum of all
displays, only consider the rightmost and bottommost tiles.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Tested-by: Hai Li <hali@codeaurora.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_fb_helper.c

@@ -1034,9 +1034,16 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 	crtc_count = 0;
 	for (i = 0; i < fb_helper->crtc_count; i++) {
 		struct drm_display_mode *desired_mode;
-		int x, y;
+		struct drm_mode_set *mode_set;
+		int x, y, j;
+		/* in case of tile group, are we the last tile vert or horiz?
+		 * If no tile group you are always the last one both vertically
+		 * and horizontally
+		 */
+		bool lastv = true, lasth = true;
 
 		desired_mode = fb_helper->crtc_info[i].desired_mode;
+		mode_set = &fb_helper->crtc_info[i].mode_set;
 
 		if (!desired_mode)
 			continue;
@@ -1051,7 +1058,20 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 
 		sizes.surface_width  = max_t(u32, desired_mode->hdisplay + x, sizes.surface_width);
 		sizes.surface_height = max_t(u32, desired_mode->vdisplay + y, sizes.surface_height);
+
+		for (j = 0; j < mode_set->num_connectors; j++) {
+			struct drm_connector *connector = mode_set->connectors[j];
+			if (connector->has_tile) {
+				lasth = (connector->tile_h_loc == (connector->num_h_tile - 1));
+				lastv = (connector->tile_v_loc == (connector->num_v_tile - 1));
+				/* cloning to multiple tiles is just crazy-talk, so: */
+				break;
+			}
+		}
+
+		if (lasth)
 			sizes.fb_width  = min_t(u32, desired_mode->hdisplay + x, sizes.fb_width);
+		if (lastv)
 			sizes.fb_height = min_t(u32, desired_mode->vdisplay + y, sizes.fb_height);
 	}