diff --git a/docs/getting_started/porting-guide.rst b/docs/getting_started/porting-guide.rst
index 7f38054..aa57e1d 100644
--- a/docs/getting_started/porting-guide.rst
+++ b/docs/getting_started/porting-guide.rst
@@ -1502,8 +1502,8 @@
 - This function indicates whether cache management operations should be
   performed. It returns 0 if CMOs should be skipped and non-zero
   otherwise.
-- The function must not clobber x2 and x3. It's also not safe to rely on stack.
-  Otherwise obey AAPCS.
+- The function must not clobber x1, x2 and x3. It's also not safe to rely on
+  stack. Otherwise obey AAPCS.
 
 Modifications specific to a Boot Loader stage
 ---------------------------------------------
diff --git a/lib/aarch64/cache_helpers.S b/lib/aarch64/cache_helpers.S
index 67fafb1..314ed6e 100644
--- a/lib/aarch64/cache_helpers.S
+++ b/lib/aarch64/cache_helpers.S
@@ -217,6 +217,7 @@
 
 
 func dcsw_op_louis
+	check_plat_can_cmo
 	dcsw_op #LOUIS_SHIFT, #CLIDR_FIELD_WIDTH, #LEVEL_SHIFT
 endfunc dcsw_op_louis