diff --git a/Documentation/components/drivers/special/mmcsd.rst b/Documentation/components/drivers/special/mmcsd.rst
index 5ba08b325b5..2cd2b5d9d0e 100644
--- a/Documentation/components/drivers/special/mmcsd.rst
+++ b/Documentation/components/drivers/special/mmcsd.rst
@@ -4,3 +4,7 @@ MMCSD Device Drivers
 
 -  ``include/nuttx/mmcsd.h``. All structures and APIs needed to
    work with MMCSD drivers are provided in this header file.
+
+Implementers of SDIO lower-half drivers should refer to the
+:doc:`SDIO Driver Documentation <sdio>` for details on R2/CSD response
+handling and correctly implementing the lower-half interface.