diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index 2ebdc6d5a76e60a33d6a271ff158258a61b7908c..d5583190f3e44de77560d76c2d5a5a4cf7db62de 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -137,7 +137,10 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
 
 	if (cmd > (char *) urb->transfer_buffer) {
 		/* Send partial buffer remaining before exiting */
-		int len = cmd - (char *) urb->transfer_buffer;
+		int len;
+		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
+			*cmd++ = 0xAF;
+		len = cmd - (char *) urb->transfer_buffer;
 		ret = udl_submit_urb(dev, urb, len);
 		bytes_sent += len;
 	} else
diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c
index 0c87b1ac6b68f0d41cfd01851a14b9a092455f4f..b992644c17e6b565b414351b1e262d4b61c9f38d 100644
--- a/drivers/gpu/drm/udl/udl_transfer.c
+++ b/drivers/gpu/drm/udl/udl_transfer.c
@@ -153,11 +153,11 @@ static void udl_compress_hline16(
 		raw_pixels_count_byte = cmd++; /*  we'll know this later */
 		raw_pixel_start = pixel;
 
-		cmd_pixel_end = pixel + (min(MAX_CMD_PIXELS + 1,
-			min((int)(pixel_end - pixel) / bpp,
-			    (int)(cmd_buffer_end - cmd) / 2))) * bpp;
+		cmd_pixel_end = pixel + min3(MAX_CMD_PIXELS + 1UL,
+					(unsigned long)(pixel_end - pixel) / bpp,
+					(unsigned long)(cmd_buffer_end - 1 - cmd) / 2) * bpp;
 
-		prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
+		prefetch_range((void *) pixel, cmd_pixel_end - pixel);
 		pixel_val16 = get_pixel_val16(pixel, bpp);
 
 		while (pixel < cmd_pixel_end) {
@@ -193,6 +193,9 @@ static void udl_compress_hline16(
 		if (pixel > raw_pixel_start) {
 			/* finalize last RAW span */
 			*raw_pixels_count_byte = ((pixel-raw_pixel_start) / bpp) & 0xFF;
+		} else {
+			/* undo unused byte */
+			cmd--;
 		}
 
 		*cmd_pixels_count_byte = ((pixel - cmd_pixel_start) / bpp) & 0xFF;