View source for U-Boot recovery for STM32MP1 DHSOM via DFU

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To recover a corrupted U-Boot on a STM32MP1-based DHCOM, we can use the default fallback boot source DFU via serial link or USB to temporarily boot U-Boot SPL and U-Boot.
From this U-Boot shell we can write both bootloader images from the SD card to the boot flash.

<div class="toclimit-3">__TOC__</div>

== Requirements ==
=== Software ===
* Linux host computer ([[Virtual Machine for Application Development]] is used in this guide)
* [https://source.denx.de/u-boot/u-boot/-/tree/v2022.04 U-Boot 2022.04] for your board (download and build instructions below)
* [https://packages.debian.org/stable/dfu-util dfu-util] (for DFU boot mode)

=== Hardware ===
* STM32MP1 based DHCOM
* DHCOM Premium Developer Kit Baseboard (or Baseboards with OTG ports)
* USB cable for OTG port (Mini USB for PDK2, USB-C for PDK3) (for DFU boot mode)
* SD card (for SD card boot mode)

== Preparation ==
This installation was made on the [[Virtual Machine for Application Development]].
All console expressions refer to this Debian system, but any other debian based system should also work.

=== Install dfu-util (debian) ===
<syntaxhighlight lang="shell">
apt-get install dfu-util
</syntaxhighlight>
<syntaxhighlight lang="console">
</syntaxhighlight>

=== Download/Build U-Boot SPL and U-Boot binaries ===

==== Download prebuilt binaries ====

[https://www.dropbox.com/sh/os9so01tivajkxs/AACQ30W-7l-Zi_Zutu0Zv-Zua?dl=0 Dropbox: U-Boot_recovery_for_STM32MP1_DHSOM_via_DFU] ([https://source.denx.de/u-boot/u-boot/-/tree/v2022.04 source])

<syntaxhighlight lang="shell">
curl -LsS https://www.dropbox.com/sh/os9so01tivajkxs/AACQ30W-7l-Zi_Zutu0Zv-Zua > recovery_binaryies.zip
unzip recovery_binaryies.zip
</syntaxhighlight>
<syntaxhighlight lang="console">
Archive:  recovery_binaryies.zip
warning:  stripped absolute path spec from /
mapname:  conversion of  failed
   creating: U-Boot_v2022.04_mainline/
   creating: U-Boot_v2022.04_mainline/av96/
   creating: U-Boot_v2022.04_mainline/pdk2/
   creating: U-Boot_v2022.04_mainline/drc02/
   creating: U-Boot_v2022.04_mainline/picoitx/
 extracting: U-Boot_v2022.04_mainline/av96/u-boot.itb  
 extracting: U-Boot_v2022.04_mainline/pdk2/u-boot.itb  
 extracting: U-Boot_v2022.04_mainline/drc02/u-boot.itb  
 extracting: U-Boot_v2022.04_mainline/picoitx/u-boot.itb  
 extracting: U-Boot_v2022.04_mainline/av96/u-boot-spl.stm32  
 extracting: U-Boot_v2022.04_mainline/pdk2/u-boot-spl.stm32  
 extracting: U-Boot_v2022.04_mainline/drc02/u-boot-spl.stm32  
 extracting: U-Boot_v2022.04_mainline/picoitx/u-boot-spl.stm32  
</syntaxhighlight>

==== Build binaries from source ====

Clone U-Boot mainline source code for release v2022.04:
<syntaxhighlight lang="shell">
UBOOT_SRC=/work/dev/u-boot_v2022.04
mkdir -p $UBOOT_SRC
git clone --branch v2022.04 --depth 1 https://source.denx.de/u-boot/u-boot.git $UBOOT_SRC
cd $UBOOT_SRC
</syntaxhighlight>

Available U-Boot defconfigs for STM32MP1 based DHSOM devices with default device tree in bold:
* '''stm32mp15_dhcom_basic_defconfig''' ('''pdk2''', picoitx, drc02)
* '''stm32mp15_dhcor_basic_defconfig''' ('''avenger96''')
<syntaxhighlight lang="shell">
mkdir -p /work/dev/u-boot
git clone https://source.denx.de/u-boot/u-boot.git -b v2022.04 /work/dev/u-boot
cd /work/dev/u-boot
ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- make stm32mp15_dhcom_basic_defconfig
</syntaxhighlight>

Change default device tree (Example for: stm32mp15xx-dhcom-picoitx):
<syntaxhighlight lang="shell">
sed -iE 's/(stm32mp15xx-dhcom-pdk2|stm32mp157a-dhcor-avenger96)/stm32mp15xx-dhcom-picoitx/' .config
</syntaxhighlight>

Build linux binaries with all available cores:
<syntaxhighlight lang="shell">
ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- make -j$(nproc)
</syntaxhighlight>
<syntaxhighlight lang="console">
...
SHIPPED dts/dt.dtb
CAT     u-boot-dtb.bin
MKIMAGE u-boot.img
COPY    u-boot.dtb
MKIMAGE u-boot-dtb.img
MKIMAGE u-boot.itb
...
LD      spl/u-boot-spl
OBJCOPY spl/u-boot-spl-nodtb.bin
SYM     spl/u-boot-spl.sym
CAT     spl/u-boot-spl-dtb.bin
COPY    spl/u-boot-spl.bin
BINMAN  all
</syntaxhighlight>

Check that the required binaries have been created and are of the appropriate size:
<syntaxhighlight lang="shell">
ls -l u-boot.itb u-boot-spl.stm32
</syntaxhighlight>
<syntaxhighlight lang="console">
-rw-r--r-- 1 devel devel 819720 Apr 11 17:03 u-boot.itb
-rw-r--r-- 1 devel devel 124288 Apr 11 17:03 u-boot-spl.stm32
</syntaxhighlight>

== U-Boot booting via DFU ==

To boot U-Boot SPL and U-Boot via DFU boot mode, you must first check if you have a DFU device connected, then load U-Boot SPL into the SRAM of your STM32MP1 and wait until the DRAM is initialized.
Then load U-Boot in the DRAM of your STM32MP1 and continue the boot process using the shown key combination.

=== Check for available DFU device ===

(Re-)Connect the USB cable with your host computer and the OTG port of your baseboard and check the kernel log for a available DFU device:
<syntaxhighlight lang="shell">
sudo dmesg
</syntaxhighlight>
<syntaxhighlight lang="console" highlight="4">
...
usb 2-2: New USB device found, idVendor=0483, idProduct=df11, bcdDevice= 2.00
usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 2-2: Product: DFU in HS Mode @Device ID /0x500, @Revision ID /0x0000
usb 2-2: Manufacturer: STMicroelectronics
usb 2-2: SerialNumber: 0040001D3130510439373430
</syntaxhighlight>

=== Download of U-Boot SPL with <code>dfu-util</code> ===

Download of U-Boot SPL with dfu-util to connected device:
<syntaxhighlight lang="shell">
dfu-util -a 1 -D u-boot-spl.stm32
</syntaxhighlight>
<syntaxhighlight lang="console">
dfu-util 0.9

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

dfu-util: Invalid DFU suffix signature
dfu-util: A valid DFU suffix will be required in a future dfu-util release!!!
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 0110
Claiming USB DFU Interface...
Setting Alternate Setting #1 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 0110
Device returned transfer size 1024
Copying data from PC to DFU device
Download	[=========================] 100%       160911 bytes
Download done.
state(7) = dfuMANIFEST, status(0) = No error condition is present
state(2) = dfuIDLE, status(0) = No error condition is present
Done!
</syntaxhighlight>

Output of the serial console:
<syntaxhighlight lang="console">
U-Boot SPL 2022.04 (Apr 05 2022 - 08:27:30 +0200)
Model: STMicroelectronics STM32MP15xx DHCOM Premium Developer Kit (2)
Code:  SoM:rev=1,ddr3=3 Board:rev=0
RAM: DDR3L 32bits 2x4Gb 533MHz
Trying to boot from DFU
</syntaxhighlight>

=== Download of U-Boot with <code>dfu-util</code> === 

Download of U-Boot with dfu-util to connected device:
<syntaxhighlight lang="shell">
dfu-util -a 0 -D u-boot.itb
</syntaxhighlight>
<syntaxhighlight lang="console">
dfu-util 0.9

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

dfu-util: Invalid DFU suffix signature
dfu-util: A valid DFU suffix will be required in a future dfu-util release!!!
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 0110
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 0110
Device returned transfer size 4096
Copying data from PC to DFU device
Download	[=========================] 100%       819232 bytes
Download done.
state(7) = dfuMANIFEST, status(0) = No error condition is present
state(2) = dfuIDLE, status(0) = No error condition is present
Done!
</syntaxhighlight>

Output of the serial console:
<syntaxhighlight lang="console">
#DOWNLOAD ... OK
Ctrl+C to exit ...
</syntaxhighlight>

Output of the serial console after pressing '''Ctrl+C''':
<syntaxhighlight lang="console">
U-Boot 2022.04 (Apr 05 2022 - 08:27:30 +0200)

CPU: STM32MP157CAA Rev.Z
Model: STMicroelectronics STM32MP15xx DHCOM Premium Developer Kit (2)
Board: stm32mp1 in basic mode (dh,stm32mp15xx-dhcom-pdk2)
DRAM:  1 GiB
Clocks:
- MPU : 650 MHz
- MCU : 208.878 MHz
- AXI : 266.500 MHz
- PER : 24 MHz
- DDR : 533 MHz
Core:  255 devices, 31 uclasses, devicetree: separate
MMC:   STM32 SD/MMC: 2, STM32 SD/MMC: 0, STM32 SD/MMC: 1
Loading Environment from SPIFlash... SF: Detected w25q16cl with page size 256 Bytes, erase size 4 KiB, total 2 MiB
OK
In:    serial
Out:   serial
Err:   serial
Net:   eth0: ethernet@5800a000, eth1: ks8851mll@64000000
Hit any key to stop autoboot:  0
</syntaxhighlight>

== U-Boot booting via SD card ==

Set the disk:
<syntaxhighlight lang="shell">
STM32_DISK=/dev/sdc
</syntaxhighlight>

=== Partition a SD card ===

Create partition table and partitions:
<syntaxhighlight lang="shell">
parted --script -- ${STM32_DISK} \
  mktable gpt \
  mkpart fsbl1 1MiB 1.25MiB \
  mkpart fsbl2 2MiB 2.25MiB \
  mkpart ssbl 3MiB 5MiB \
  mkpart rootfs ext4 5MiB 100% \
  set 4 legacy_boot on \
  unit MiB \
  print
</syntaxhighlight>
<syntaxhighlight lang="console">
Model: Generic STORAGE DEVICE (scsi)
Disk /dev/sdc: 954MiB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start    End      Size     File system  Name    Flags
 1      1.00MiB  1.25MiB  0.25MiB               fsbl1
 2      2.00MiB  2.25MiB  0.25MiB               fsbl2
 3      3.00MiB  5.00MiB  2.00MiB               ssbl
 4      5.00MiB  953MiB   948MiB   ext4         rootfs  legacy_boot
</syntaxhighlight>

Redetect partitions:
<syntaxhighlight lang="shell">
partprobe ${STM32_DISK}
</syntaxhighlight>

=== Create file system on partition 4 ===

Create filesystem on partition 4:
<syntaxhighlight lang="shell">
mkfs.ext4 -m 0 -L rootfs ${STM32_DISK}4
</syntaxhighlight>
<syntaxhighlight lang="console">
mke2fs 1.46.2 (28-Feb-2021)
Creating filesystem with 242688 4k blocks and 60672 inodes
Filesystem UUID: bda8eff7-aa5a-4ed8-aa53-f22e3a1e3203
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
</syntaxhighlight>

=== Write U-Boot SPL and U-Boot to the SD card ===

Write u-boot spl and u-boot to boot partitions 1, 2 and 3:
<syntaxhighlight lang="shell">
dd if=u-boot-spl.stm32 of=${STM32_DISK}1
dd if=u-boot-spl.stm32 of=${STM32_DISK}2
dd if=u-boot.itb of=${STM32_DISK}3
</syntaxhighlight>
<syntaxhighlight lang="console">
314+1 records in
314+1 records out
160911 bytes (161 kB, 157 KiB) copied, 0.274919 s, 585 kB/s
314+1 records in
314+1 records out
160911 bytes (161 kB, 157 KiB) copied, 0.280309 s, 574 kB/s
1600+1 records in
1600+1 records out
819232 bytes (819 kB, 800 KiB) copied, 0.862246 s, 950 kB/s
</syntaxhighlight>

Copy u-boot spl and u-boot to directory <code>boot</code> on rootfs partition 4:
<syntaxhighlight lang="shell">
mkdir -p rootfs
mount ${STM32_DISK}4 rootfs
mkdir -p rootfs/boot
cp u-boot-spl.stm32 u-boot.itb rootfs/boot/
umount rootfs && rmdir rootfs
</syntaxhighlight>

=== Boot from SD card ===

# Hold the button for SD card boot mode on the SODIMM-200 module (DHCOM) below the eMMC chip.
#:[[File:DHCOR_i.MX6ULL_SDP-Boot.jpg|400px]]
# Reset the device. To reset the device, press the reset button on the baseboard or unplug and plug in the power plug.
# Release the button for SD card boot mode

== U-Boot flashing via SD card ==

=== Write U-Boot SPL and U-Boot to the SD card ===

Follow the instruction in [[#U-Boot booting via SD card|U-Boot booting via SD card]] to prepare a SD card with a file system on partition 4, which contains the required binaries <code>u-boot-spl.stm32</code> and <code>u-boot.itb</code>.

=== Write U-Boot SPL and U-Boot to SPI-NOR-Flash ===

# Start U-Boot by [[#U-Boot booting via DFU|U-Boot booting via DFU]] or by [[#Boot from SD card|Boot from SD card]]
# Attach prepared SD card to the on module SD card slot
# Program U-Boot SPL and U-Boot by the script <code>update_sf</code> stored in the U-Boot environment.
#:<syntaxhighlight lang="shell">
STM32MP> run update_sf
</syntaxhighlight>
#:<syntaxhighlight lang="console">
160911 bytes read in 80 ms (1.9 MiB/s)
819232 bytes read in 115 ms (6.8 MiB/s)
SF: Detected w25q16cl with page size 256 Bytes, erase size 4 KiB, total 2 MiB
SF: 2097152 bytes @ 0x0 Erased: OK
device 0 offset 0x0, size 0x2748f
160911 bytes written, 0 bytes skipped in 1.664s, speed 98903 B/s
device 0 offset 0x40000, size 0x2748f
160911 bytes written, 0 bytes skipped in 1.626s, speed 101211 B/s
device 0 offset 0x80000, size 0xc8020
815136 bytes written, 4096 bytes skipped in 8.379s, speed 100094 B/s
</syntaxhighlight>