doc: board: j721e_evm: Add documentation for firmware loading

Add documentation for loading firmwares to be used by remote cores in
the system including the environment variables that has to be set to
load the firmwares.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210721155849.20994-21-kishon@ti.com

diff --git a/doc/board/ti/j721e_evm.rst b/doc/board/ti/j721e_evm.rst
index 8b46070..44dc316 100644 (file)
--- a/doc/board/ti/j721e_evm.rst
+++ b/doc/board/ti/j721e_evm.rst
@@ -314,3 +314,18 @@ Flash layout for OSPI:
              |     ospi.rootfs(UBIFS)     |
              |                            |
              +----------------------------+
+
+Firmwares:
+----------
+
+The J721e u-boot allows firmware to be loaded for the Cortex-R5 subsystem.
+The CPSW5G in J7200 and CPSW9G in J721E present in MAIN domain is configured
+and controlled by the ethernet firmware that executes in the MAIN Cortex R5.
+The default supported environment variables support loading these firmwares
+from only MMC. "dorprocboot" env variable has to be set for the U-BOOT to load
+and start the remote cores in the system.
+
+J721E common processor board can be attached to a Ethernet QSGMII card and the
+PHY in the card has to be reset before it can be used for data transfer.
+"do_main_cpsw0_qsgmii_phyinit" env variable has to be set for the U-BOOT to
+configure this PHY.