[PATCH v2 5/5] doc: board: nxp: Add Quickboot documentation

[Simona Toaca (OSS)]

From: Simona Toaca <simona.toaca at nxp.com>

Add instructions on how to use U-Boot to save
DDR training data to NVM and explain the saving
process.

Signed-off-by: Simona Toaca <simona.toaca at nxp.com>
---
 doc/board/nxp/index.rst |  1 +
 doc/board/nxp/qb.rst    | 49 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 doc/board/nxp/qb.rst

diff --git a/doc/board/nxp/index.rst b/doc/board/nxp/index.rst
index 01d3468a47d..7e3e5e29880 100644
--- a/doc/board/nxp/index.rst
+++ b/doc/board/nxp/index.rst
@@ -29,3 +29,4 @@ NXP Semiconductors
    mx6ullevk
    rproc
    psb
+   qb
diff --git a/doc/board/nxp/qb.rst b/doc/board/nxp/qb.rst
new file mode 100644
index 00000000000..5a1e913ea11
--- /dev/null
+++ b/doc/board/nxp/qb.rst
@@ -0,0 +1,49 @@
+.. SPDX-License-Identifier: GPL-2.0+
+   Copyright 2026 NXP
+
+DDR QuickBoot flow
+------------------
+
+Some NXP boards (which use OEI - iMX943, iMX95, etc.) support saving DDR
+training data (collected by OEI during Training flow) from volatile
+to non-volatile memory, which is then available to OEI at next cold reboot.
+OEI uses the saved data to run Quickboot flow and avoid training the DDR again.
+This significantly reduces the boot time.
+
+U-Boot provides no authentication for qb data, only its integrity
+is verified via the CRC32. The authentication is done in OEI. With
+the exception of iMX95 A0/A1, which use CRC32 as well for verifying
+the data, the rest of the boards use ELE to verify the MAC stored
+in the ddrphy_qb_state structure.
+
+If the quickboot data in memory is not valid (CRC32 check fails),
+U-Boot does not save it to NVM. So, if OEI runs Quickboot flow -> no
+data is written to volatile memory -> invalid data -> no saving happens
+(qb save fails during qb check).
+
+After successful saving, U-Boot clears the data in volatile memory so
+that qb check fails at next reboot and the NVM isn't accessed again.
+
+There are 2 ways to save this data (both can be enabled):
+
+1. automatically, in SPL (by enabling CONFIG_SPL_IMX_QB)
+
+- this will save the data on the current boot device (e.g. SD)
+- other configs specific to the boot device need to be enabled (CONFIG_SPL_MMC_WRITE for saving to eMMC/SD)
+- use for: automating qb save / saving qb data if using Falcon mode (skipping U-Boot proper)
+
+2. using qb command in U-Boot console (by enabling CONFIG_CMD_IMX_QB)
+
+- supports saving on the current boot device, or on another, specified device.
+- if flashing via uuu, the command can be added in an uuu script (boot device needs to be specified)
+- use for: saving the qb data during flashing / controlling the NVM to save to
+
+::
+
+        # To save/erase on current boot device
+        => qb save/erase
+
+        # To save/erase on other boot device
+        => qb save/erase mmc 0 # eMMC
+        => qb save/erase mmc 1 # SD
+        => qb save/erase spi   # NOR SPI
-- 
2.43.0