drm: xlnx: mixer: Return error if requested dimensions not scaleable

In case the mixer is not able to scale to application requested dimensions
then return error during check.

Signed-off-by: Devarsh Thakkar <devarsh.thakkar@xilinx.com>

drivers/gpu/drm/xlnx/xlnx_mixer.c

@@ -2026,14 +2026,27 @@ static int xlnx_mix_plane_atomic_check(struct drm_plane *plane,
 	struct xlnx_mix_plane *mix_plane = to_xlnx_plane(plane);
 	struct xlnx_mix_hw *mixer_hw = to_mixer_hw(mix_plane);
 	struct xlnx_mix *mix;
+	int scale_factor[3] = {1, 2, 4};
+	int fb_width = 0, fb_height = 0;
 
+	if (state->fb) {
+		fb_width = state->fb->width;
+		fb_height = state->fb->height;
+	}
 	/* No check required for the drm_primary_plane */
 	mix = container_of(mixer_hw, struct xlnx_mix, mixer_hw);
 	if (mix->drm_primary_layer == mix_plane)
 		return 0;
 
 	scale = xlnx_mix_get_layer_scaling(mixer_hw,
 					   mix_plane->mixer_layer->id);
+
+	if (state->fb && ((fb_width * scale_factor[scale] != state->crtc_w) ||
+			  (fb_height * scale_factor[scale] != state->crtc_h))) {
+		DRM_DEBUG_KMS("Not possible to scale to desired dimensions\n");
+		return -EINVAL;
+	}
+
 	if (is_window_valid(mixer_hw, state->crtc_x, state->crtc_y,
 			    state->src_w >> 16, state->src_h >> 16, scale))
 		return 0;