docs: x4xx: Update information on CPLD updating

2 files changed, 30 insertions, 0 deletions

diff --git a/host/docs/usrp_x4xx.dox b/host/docs/usrp_x4xx.dox
index 8078734c5..23a560d7d 100644
--- a/host/docs/usrp_x4xx.dox
+++ b/host/docs/usrp_x4xx.dox
@@ -539,11 +539,22 @@ Otherwise, let the boot continue as normal.
 <b>Caution! Updating the motherboard CPLD has the potential to brick your
 device if done improperly.</b>
 
+After updating the filesystem, you may have to update your motherboard CPLD. If
+you forget to update the CPLD, MPM will fail to fully initialize and emit a
+warning. This is not critical, and the CPLD update can be performed later by
+following these same steps, but the device will not be usable until then.
+
+Even though the CPLD may not require updating, it is recommended to always run
+these steps for a consistent update procedure.
+
 You can update the motherboard (MB) CPLD by running the following command on
 the X410:
 
     x4xx_update_cpld --file=<path to cpld-x410.rpd>
 
+Note: Old filesystems may not contain this command. If you are performing a
+mender update, simply run these commands after the update.
+
 Filesystems will usually contain a compatible `cpld-x410.rpd` file at
 `/lib/firmware/ni/cpld-x410.rpd`. If you're installing a new filesystem via
 mender, you may have to mount the new filesystem (before you boot into it) in
diff --git a/host/docs/zbx.dox b/host/docs/zbx.dox
index 3d6a3e527..727a00b7d 100644
--- a/host/docs/zbx.dox
+++ b/host/docs/zbx.dox
@@ -420,6 +420,10 @@ The "software defined" mode can be enabled for the DSA tables by using the
 
 \section zbx_updating_cpld Updating the ZBX CPLD
 
+Note: You may need to update the ZBX CPLD after updating filesystems. If an
+update is required, MPM will fail to initialize, and provide a corresponding
+error message.
+
 If you need to update the ZBX CPLD, you can do so by running the following command
 on the device:
 
@@ -436,6 +440,21 @@ By default, the `cpld-zbx.rpd` file will be provided at
 `/lib/firmware/ni/cpld-zbx.rpd`. Note that after downloading the ZBX CPLD, you
 will need to completely shut down and power-cycle the device.
 
+If you are updating the image during a filesystem update, i.e., after installing
+the new filesystem with Mender, but before rebooting, you will need to mount
+the new filesystem first and copy the image over:
+
+    mkdir /mnt/other
+    mount /dev/mmcblk0p3 /mnt/other
+    cp /mnt/other/lib/firmware/ni/cpld-zbx.rpd ~
+    umount /mnt/other
+
+Note that the other filesystem may be either `/dev/mmcblk0p2` or `/dev/mmcblk0p3`.
+You can now update to the new CPLD image:
+
+    zbx_update_cpld --file=~/cpld-zbx.rpd
+
+
 \subsection zbx_updating_cpld_details CPLD Programming: Details
 
 Read this section if you want to create your own ZBX CPLD image, or require more