diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 1e6a0c760c5d..dca98a40a550 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1035,22 +1035,24 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 	for (i = 0; i < fb_helper->crtc_count; i++) {
 		struct drm_display_mode *desired_mode;
 		int x, y;
+
 		desired_mode = fb_helper->crtc_info[i].desired_mode;
+
+		if (!desired_mode)
+			continue;
+
+		crtc_count++;
+
 		x = fb_helper->crtc_info[i].x;
 		y = fb_helper->crtc_info[i].y;
-		if (desired_mode) {
-			if (gamma_size == 0)
-				gamma_size = fb_helper->crtc_info[i].mode_set.crtc->gamma_size;
-			if (desired_mode->hdisplay + x < sizes.fb_width)
-				sizes.fb_width = desired_mode->hdisplay + x;
-			if (desired_mode->vdisplay + y < sizes.fb_height)
-				sizes.fb_height = desired_mode->vdisplay + y;
-			if (desired_mode->hdisplay + x > sizes.surface_width)
-				sizes.surface_width = desired_mode->hdisplay + x;
-			if (desired_mode->vdisplay + y > sizes.surface_height)
-				sizes.surface_height = desired_mode->vdisplay + y;
-			crtc_count++;
-		}
+
+		if (gamma_size == 0)
+			gamma_size = fb_helper->crtc_info[i].mode_set.crtc->gamma_size;
+
+		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);
+		sizes.fb_width  = min_t(u32, desired_mode->hdisplay + x, sizes.fb_width);
+		sizes.fb_height = min_t(u32, desired_mode->vdisplay + y, sizes.fb_height);
 	}
 
 	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {