doc: release-notes/3.3: update release notes for sd subystem
Update release notes for SD subsystem. The following changes are present:
SD subsystem now supports eMMC
SD cards that support only high speed mode now use 4 bit bus width
@@ -1084,6 +1084,18 @@ Libraries / Subsystems
* The ``lwm2m_senml_cbor_*`` files have been regenerated using zcbor 0.6.0.
+* SD Subsystem
+
+ * Added support for eMMC protocol in Zephyr.
+
+ - Speed modes up to HS400 are supported using 1.8v operation.
+ - Additional protocol tests have been added to verify eMMC functionality.
+ - Disk subsystem tests have been updated to function with eMMC.
+
+ * Card and host combinations that cannot utilize UHS (ultra high speed) mode
+ will now use 4 bit bus width when possible. This will greatly improve
+ performance for these systems.
+
* Settings
* Replaced all :c:func:`k_panic` invocations within settings backend
