diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index a49e4ae92653..49db221c0f52 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -121,8 +121,7 @@ There's lots of plane features we could add support for:
 - ARGB format on primary plane: blend the primary plane into background with
   translucent alpha.
 
-- Support when the primary plane isn't exactly matching the output size: blend
-  the primary plane into the black background.
+- Add background color KMS property[Good to get started].
 
 - Full alpha blending on all planes.
 
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index 5b1a8bdd8268..8e53fa80742b 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -61,6 +61,13 @@ static bool check_y_limit(struct vkms_frame_info *frame_info, int y)
 	return false;
 }
 
+static void fill_background(const struct pixel_argb_u16 *background_color,
+			    struct line_buffer *output_buffer)
+{
+	for (size_t i = 0; i < output_buffer->n_pixels; i++)
+		output_buffer->pixels[i] = *background_color;
+}
+
 /**
  * @wb_frame_info: The writeback frame buffer metadata
  * @crtc_state: The crtc state
@@ -78,21 +85,17 @@ static void blend(struct vkms_writeback_job *wb,
 		  struct line_buffer *output_buffer, size_t row_size)
 {
 	struct vkms_plane_state **plane = crtc_state->active_planes;
-	struct vkms_frame_info *primary_plane_info = plane[0]->frame_info;
 	u32 n_active_planes = crtc_state->num_active_planes;
 
-	int y_dst = primary_plane_info->dst.y1;
-	int h_dst = drm_rect_height(&primary_plane_info->dst);
-	int y_limit = y_dst + h_dst;
+	const struct pixel_argb_u16 background_color = { .a = 0xffff };
 
-	for (size_t y = y_dst; y < y_limit; y++) {
-		plane[0]->plane_read(output_buffer, primary_plane_info, y);
+	size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
 
-		/* If there are other planes besides primary, we consider the active
-		 * planes should be in z-order and compose them associatively:
-		 * ((primary <- overlay) <- cursor)
-		 */
-		for (size_t i = 1; i < n_active_planes; i++) {
+	for (size_t y = 0; y < crtc_y_limit; y++) {
+		fill_background(&background_color, output_buffer);
+
+		/* The active planes are composed associatively in z-order. */
+		for (size_t i = 0; i < n_active_planes; i++) {
 			if (!check_y_limit(plane[i]->frame_info, y))
 				continue;
 
@@ -124,14 +127,24 @@ static int check_format_funcs(struct vkms_crtc_state *crtc_state,
 	return 0;
 }
 
+static int check_iosys_map(struct vkms_crtc_state *crtc_state)
+{
+	struct vkms_plane_state **plane_state = crtc_state->active_planes;
+	u32 n_active_planes = crtc_state->num_active_planes;
+
+	for (size_t i = 0; i < n_active_planes; i++)
+		if (iosys_map_is_null(&plane_state[i]->frame_info->map[0]))
+			return -1;
+
+	return 0;
+}
+
 static int compose_active_planes(struct vkms_writeback_job *active_wb,
 				 struct vkms_crtc_state *crtc_state,
 				 u32 *crc32)
 {
 	size_t line_width, pixel_size = sizeof(struct pixel_argb_u16);
-	struct vkms_frame_info *primary_plane_info = NULL;
 	struct line_buffer output_buffer, stage_buffer;
-	struct vkms_plane_state *act_plane = NULL;
 	int ret = 0;
 
 	/*
@@ -142,22 +155,13 @@ static int compose_active_planes(struct vkms_writeback_job *active_wb,
 	 */
 	static_assert(sizeof(struct pixel_argb_u16) == 8);
 
-	if (crtc_state->num_active_planes >= 1) {
-		act_plane = crtc_state->active_planes[0];
-		if (act_plane->base.base.plane->type == DRM_PLANE_TYPE_PRIMARY)
-			primary_plane_info = act_plane->frame_info;
-	}
-
-	if (!primary_plane_info)
-		return -EINVAL;
-
-	if (WARN_ON(iosys_map_is_null(&primary_plane_info->map[0])))
+	if (WARN_ON(check_iosys_map(crtc_state)))
 		return -EINVAL;
 
 	if (WARN_ON(check_format_funcs(crtc_state, active_wb)))
 		return -EINVAL;
 
-	line_width = drm_rect_width(&primary_plane_info->dst);
+	line_width = crtc_state->base.crtc->mode.hdisplay;
 	stage_buffer.n_pixels = line_width;
 	output_buffer.n_pixels = line_width;
 
@@ -174,13 +178,6 @@ static int compose_active_planes(struct vkms_writeback_job *active_wb,
 		goto free_stage_buffer;
 	}
 
-	if (active_wb) {
-		struct vkms_frame_info *wb_frame_info = &active_wb->wb_frame_info;
-
-		wb_frame_info->src = primary_plane_info->src;
-		wb_frame_info->dst = primary_plane_info->dst;
-	}
-
 	blend(active_wb, crtc_state, crc32, &stage_buffer,
 	      &output_buffer, line_width * pixel_size);
 
diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c b/drivers/gpu/drm/vkms/vkms_writeback.c
index d2aabb52cb46..974db5defce4 100644
--- a/drivers/gpu/drm/vkms/vkms_writeback.c
+++ b/drivers/gpu/drm/vkms/vkms_writeback.c
@@ -122,6 +122,8 @@ static void vkms_wb_atomic_commit(struct drm_connector *conn,
 	struct drm_connector_state *conn_state = wb_conn->base.state;
 	struct vkms_crtc_state *crtc_state = output->composer_state;
 	struct drm_framebuffer *fb = connector_state->writeback_job->fb;
+	u16 crtc_height = crtc_state->base.crtc->mode.vdisplay;
+	u16 crtc_width = crtc_state->base.crtc->mode.hdisplay;
 	struct vkms_writeback_job *active_wb;
 	struct vkms_frame_info *wb_frame_info;
 	u32 wb_format = fb->format->format;
@@ -143,6 +145,8 @@ static void vkms_wb_atomic_commit(struct drm_connector *conn,
 	spin_unlock_irq(&output->composer_lock);
 	drm_writeback_queue_job(wb_conn, connector_state);
 	active_wb->wb_write = get_line_to_frame_function(wb_format);
+	drm_rect_init(&wb_frame_info->src, 0, 0, crtc_width, crtc_height);
+	drm_rect_init(&wb_frame_info->dst, 0, 0, crtc_width, crtc_height);
 }
 
 static const struct drm_connector_helper_funcs vkms_wb_conn_helper_funcs = {
