diff --git a/Documentation/block/cmdline-partition.rst b/Documentation/block/cmdline-partition.rst
index 530bedff548a..526ba201dddc 100644
--- a/Documentation/block/cmdline-partition.rst
+++ b/Documentation/block/cmdline-partition.rst
@@ -39,13 +39,16 @@ blkdevparts=<blkdev-def>[;<blkdev-def>]
     create a link to block device partition with the name "PARTNAME".
     User space application can access partition by partition name.
 
+ro
+    read-only. Flag the partition as read-only.
+
 Example:
 
     eMMC disk names are "mmcblk0" and "mmcblk0boot0".
 
   bootargs::
 
-    'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)'
+    'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot)ro,-(kernel)'
 
   dmesg::