[PATCH] Documentation: boards: stm32mp: document eMMC boot configuration

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

In order to boot from eMMC on the STM32MP15x, the boot_ack bit in the
ext_csd register must be set. Document this and while at it, fix a
misformatted code block in the same section.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 Documentation/boards/stm32mp.rst | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/boards/stm32mp.rst b/Documentation/boards/stm32mp.rst
index 607c59fd0757..fc8a68cf4142 100644
--- a/Documentation/boards/stm32mp.rst
+++ b/Documentation/boards/stm32mp.rst
@@ -63,7 +63,7 @@ An appropriate image for a SD-Card can be generated with following
   }
 
 For eMMC, the boot partitions are used as the FSBL partitions and so the user
-partitions may look like this:
+partitions may look like this::
 
   image @STM32MP_BOARD@.img {
       partition ssbl {
@@ -79,6 +79,14 @@ partitions may look like this:
 The fsbl1 and fsbl2 can be flashed by writing to barebox ``/dev/mmcX.boot0`` and
 ``/dev/mmcX.boot1`` respectively or from a booted operating system.
 
+Additionally, the eMMC's ``ext_csd`` register must be modified to activate the
+boot acknowledge signal and to select a boot partition, e.g.::
+
+  mmcX.boot_ack=1
+  mmcX.boot=boot0
+
+The STM32MP1 BootROM does *not* support booting eMMC without fast boot acknowledge.
+
 Boot source selection
 ---------------------
 
-- 
2.26.2


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox