COM iMX6 Bootloader U-Boot

FAQ

Q: U-Boot doesn't start anymore?

A: See U-Boot recovery for i.MX6_Q/D/DL/S/ULL via JTAG

Q: Initialization of MAC address in the bootloader?

A: At the first start, the bootloader reads the MAC address from the EEPROM and creates env variable ethaddr. The env variable ethaddr could be changed during lifetime to any other MAC address. If you like to get back the original MAC address, please remove ethaddr, save environment and restart the system. In addition to that the env variable ethaddr would be initialized again with eeprom MAC address.

Q: The automatic update is not executed before the operating system boots!

A: Check if the command update auto is included in the bootloader environment variable bootcmd or in a script-variable which is called within bootcmd before bootm.

Q: The automatic update does not work with my desired update-media!

A: The command update auto can be configured with flags within the DHCOM settings.bin block. It is possible to disable a interface for the update mechanism. You can run a update from a disabled interface if you use the command update without the argument auto.

Downloads

Please have a look at the i.MX6 Download binaries/images section.

Enter Bootloader Console

1. Connect DHCOM UART1 via null modem cable to the RS232 Port of your PC
2. Start terminal program (e.g. Tera Term) on the Host PC with the following settings:

   Baud rate: 115200

   Data: 8 bit

   Parity: none

   Stop bits: 1 bit

   Flow control: none

3. Press "DEL" on the Host PC during Core Module system start to enter bootloader console

U-Boot recovery

See U-Boot recovery for i.MX6_Q/D/DL/S/ULL via JTAG

U-boot console commands

SPI Flash

SPI Flash Init

sf probe

Example: sf probe

Description: Initializes the OnBoard SPI Flash

SPI Flash Read

sf read <SDRAM address> <SPI Flash address> <Bytes>

Example: sf read 10000000 0 100

Description: Copies 256Bytes from SPI Flash address 0x0 to SDRAM address 0x1000_0000

SPI Flash Write

sf write <SDRAM address> <SPI Flash address> <Bytes>

Example: sf write 10000000 40000 10000

Description: Copies 64kByte from SDRAM address 0x1000_0000 to SPI Flash address 0x4_0000

SPI Flash Erase

sf erase <SPI Flash address> <Bytes>

Example: sf erase 100000 1000

Description: Deletes SPI Flash content from address 0x10_0000 to 0x10_0FFF

Note: The Bytes information needs to be sector size aligned!

NAND-Flash

Read from NAND-Flash Device

nand read <SDRAM address> <NAND Flash address> <Bytes>

Example: nand read 80000000 400000 b40000

Description: Copies 11,25MByte from NAND Flash address 0x40_0000 to SDRAM address 0x8000_0000

Erase NAND-Flash blocks

nand erase <Block base address> <Bytes>

Example: nand erase 400000 40000

Description: Deletes NAND Flash content from address 0x40_0000 to 0x43_FFFF

Note: The Bytes information needs to be block size aligned!

Write to NAND-Flash Device

nand write <SDRAM address> <NAND-Flash address> <Bytes>

Example: nand write 80000000 400000 b40000

Description: Copies 11,25MByte from SDRAM address 0x8000_0000 to NAND Flash address 0x40_0000

Note: The Bytes information needs to be page size aligned!

Show bad NAND-Flash blocks

nand bad

Description: Shows the bad NAND-Flash blocks.

Show NAND-Flash content

nand dump <NAND-Flash address>

Example: nand dump 400000

Description: Shows the content of the specified NAND-Flash block

UBI Filesystem

Partition Definition

mtdparts

Example: mtdparts

Description: Shows the current nand flash partitions. In case of i.MX6 one default partition set, which includes the entire flash. For linux that partition is used to create two volumes "boot" and "rootfs".

Note: In case of UBIFS it is better to have one big partition with different volumes instead of many small partitions, because the wear leveling process is always applied to every partition.

device nand0 <gpmi-nand>, # parts = 1
 #: name                size            offset          mask_flags
 0: gpmi-nand           0x20000000      0x00000000      0
active partition: nand0,0 - (gpmi-nand) 0x20000000 @ 0x00000000

Set or show active partition

ubi part <partition name>

Example: ubi part gpmi-nand

Description: Show or set current partition. In i.MX6 default case this is shold always set to gpmi-nand.

Show ubi layout information

ubi info layout

Example: ubi info layout

Description: Display ubi layout information.

Mount UBI volume

ubifsmount <UBI device>:<volume name>

Example: ubifsmount ubi0:boot

Description: Mount UBIFS volume. The default name of the first i.MX6 volume is "boot".

List files

ubifsls <directory>

Example 1: ubifsls

Description: List files in a UBIFS directory.

Load Files from UBI volume

ubifsload <SDRAM address> <directory+filename>

Example 1: ubifsload 10100000 zimage

Description: Load file from an UBIFS filesystem to memory.

Unmount UBI volume

ubifsumount

Example: ubifsumount

Description: Unmount current volume.

SD/MMC Card

Switch between MicroSD, SD Slot and eMMC

mmc dev <Slot number> <Partition number>

Example: mmc dev 0

Description: Switch between SD/MMC Slots: 0 => SD/MMC Slot | 1 => MicroSD Slot | 2 => eMMC

Note eMMC hardware partition number: 0 => User partition | 1 => first boot partition | 2 => second boot partition

Initialize SD/MMC Card

mmc rescan

Description: Initialize new inserted SD Card

Show SD/MMC information

mmcinfo

Description: Shows SD/MMC device information

Device: FSL_SDHC
Manufacturer ID: 45
OEM: 100
Name: SEM08
Tran Speed: 52000000
Rd Block Len: 512
MMC version 4.41
High Capacity: Yes
Capacity: 7.3 GiB
Bus Width: 8-bit

Write to MicroSD, SD Slot and eMMC

mmc write <SDRAM address> <block number> <block count>

Example: mmc write 11000000 5000 400

Description: Write 512kByte (device block size is 512Byte) to the eMMC offset 10MByte.

Read from MicroSD, SD Slot and eMMC

mmc read <SDRAM address> <block number> <block count>

Example: mmc read 11000000 5000 400

Description: Read 512kByte (device block size is 512Byte) from the eMMC offset 10MByte.

Filesystem

NOTE: File system types are recognized automatically

List files

ls <interface> <device[:partition]> <directory>

Example 1: ls mmc 1

Example 2: ls mmc 1 /folder

Load Files from device to SDRAM

load <interface> <device[:partition]> <SDRAM address> <directory+filename>

Example 1: load mmc 1 10100000 nk.gz

Example 2: load mmc 1 10100000 /folder/nk.gz

Ethernet

Load File via TFTP to SDRAM

tftp <SDRAM address> <directory+filename>

Example: tftp 80100000 nk.gz

Example TFTP Server: "Winagents TFTP Server Manager"

Note: For TFTP download it is necessary to config the ENV variables "ipaddr" and "serverip"

Load File via TFTP to SDRAM using DHCP

dhcp <SDRAM address> <directory+filename>

Example: dhcp 80100000 nk.gz

Example TFTP Server: "Winagents TFTP Server Manager"

Note: It is necessary to config the ENV variable "serverip" with the ip-address of your TFTP-Server

Ping

ping <IP address>

Example: ping 192.168.55.32

Unzip

unzip <source address> <destination address>

Example: unzip 12900000 10100000

Note: The unzip command is supporting the gzip file format.

Bitmap

Information

bmp info <Bitmap address>

Image size    : 800 x 480
Bits per pixel: 8
Compression   : 0

Display

bmp display <Bitmap SDRAM address> [x y]

Note: It is necessary to load bitmap file to memory address with an offset of an odd multiple of +2, since the use of a four-byte alignment will cause alignment exceptions at run-time.

Memory

Display

md[.b, .w, .l] <address> [count]

Example: md.b 80100000 100

Write

mw[.b, .w, .l] <address> <value> [count]

Example: mw.b 80100000 aa 100

Description: Writes the value 0xaa to the next 0x100 bytes from the address 0x8010_0000.

Copy

cp[.b, .w, .l] <source> <destination> <count>

Show DHCOM Settings

settings

Example:

 VALIDATION_ID:    "DH"
 DISPLAY_ID:       0x00
 LENGTH:           0x2c
 X_RESOLUTION:     800 pixel
 Y_RESOLUTION:     480 pixel
 PIXEL_CLOCK:      22200 kHz
 LCD_CONFIG_FLAGS: 0x3e3
 HSW:              64 pixel clocks
 VSW:              2 line clocks
 HFP:              42 pixel clocks
 HBP:              86 pixel clocks
 VFP:              10 line clocks
 VBP:              33 line clocks
 DATALINES:        16
 ACB:              0
 ACBI:             0
 GPIO_DIR:         0x01ff
 GPIO_STATE:       0x0000
 HW_CONFIG_FLAGS:  0x001e

I2C

Set current I2C bus

i2c dev <I2C bus>

Example: i2c dev 0

Description: Set current I2C bus to 0.

Valid buses on i.MX6:
0 = DHCOM I2C port 1
1 = DHCOM I2C port 2
2 = i.MX6 OnBoard I2C port

List available devices

i2c probe

Description: Test for and show device(s) on the I2C bus.

Valid chip addresses: 32 50 51 52 53 58 59

Read

i2c md <I2C address> <start address> <end address>

Example: i2c md 57 10 20

Description: Reads 16 Bytes from the address 0x10 to address 0x20.

Write

i2c mw <I2C address> <I2C register> <Value> <Bytes>

Example: i2c mw 57 0 aa 5

Description: Writes 0xaa to 5 Bytes from the offset 0.

Environment

Show ENV variables

env print

or

printenv

bootdelay=0
baudrate=38400
ipaddr=192.168.55.230
serverip=192.168.55.36
gatewayip=192.168.55.36
netmask=255.255.255.0
frias=5
...
Environment size: 449/262140 bytes

Set ENV variables

env set <ENV name> <ENV value>

or

setenv <ENV name> <ENV value>

Example: env set ipaddr 192.168.55.2

Note: If you need to edit "bootcmd" it is necessary to insert ; between the unique commands. Put the whole sequence in quotation marks '...'.

Save ENV variables

env save

or

saveenv

Delete ENV variable

env delete <ENV name>

Revert to default ENV (all)

env default -a

Import ENV from textfile

env import -t <SDRAM address> $filesize

Example:

load mmc 0 0x10000000 uLinuxEnv.txt

env import -t 0x10000000 $filesize

Important:

The uLinuxEnv.txt file should have unix line ending. Also make sure that there is an empty line at the end of the file.

USB Mass Storage

Use device as USB Mass Storage

ums <USB_controller> <devtype> <dev[:part]>

Example: Write an image on PDK2 to the eMMC using the "ums" command:

1. Connect the USB OTG on the PDK2 with a suitable cable to a computer running Debian Linux

2. Go to the U-Boot console on the module

3. Start UMS by typing:

ums 0 mmc 2

4. Eject partitions that may appear

5. Double klick on the image (*.img.xz file)

6. Select a destination drive

7. Press "Start Restoring..."

8. Stop UMS in U-Boot by pressing CTRL+C

How to do Updates

DHCOM Update Mechanism

Display and Hardware settings

DHCOM settings and Splash bitmap

The DHCOM settings are used to setup display and special hardware parameters. For detailed description please have a look at How to create a settings.bin file.

The DHCOM settings file and the splash bitmap are loaded via the env variables "load_settings_bin" and "load_splash" during startup from boot partition. The default content of these env variables is:

settings_bin_file=settings.bin
splash_file=splash.bmp
load_settings_bin=load mmc ${mmcdev}:${mmcpart} ${loadaddr} ${settings_bin_file}
load_splash=load mmc ${mmcdev}:${mmcpart} ${loadaddr} ${splash_file}

Note: The DHCOM display settings can also be stored in external eeprom (address 0x50 / 7bit I2C address) which is connected to DHCOM I2C1 port. If eeprom is available and DISP_ADPT_EEPRM flag is set to 1, the settings from eeprom override the settings from boot partition!

Next you can see the settings load order:

Displaying a splash screen with u-boot

Notes:

• This is possible with u-boot version v1.0.0.6 or newer.
• Only RGB interface and LVDS (only first channel) is supported.
• If you use lvds panel on vendor Kernel 3.10.17 the linux patch “imx6 clk: Init LDB (lvds) parent clock“ (19.Jan 2016) is needed, because otherwise the display isn’t working properly in linux.
  (https://github.com/dh-electronics/linux-imx6-vendor/commit/6f7cabb4d7504c4d1cfe244d460f9891d5a0e411 )

The process to set it up is the following:

• Configure your display parameters with DHCOM settings generator (How to create a settings.bin file)
  Here you can see an LVDS display example:
  
• Generate settings bin file with settings generator.
• Copy settings bin file to boot partition on boot media (eMMC, NAND or microSD card).
• Generate your splash bitmap (bitmap with 8 bit color depth).
• Copy also bmp file to boot partition.
• Start core module and enter u-boot console.
• Delete env variable “panel”: env delete panel
• Set env variable “settings_bin_file” with settings bin filename:
  Example: env set settings_bin_file 10_LG_7inch_LB070WV8.bin
• Set env variable “splash_file” with bitmap filename:
  Example: env set splash_file 800x480_splash_DHCOM_iMX6.bmp
• Save u-boot environment to flash: saveenv
• Restart the system --> Splash bitmap should now be displayed from the bootloader.

Generated Linux boot args for the display by u-boot

• U-boot is generating Linux boot args from the display settings file:

Display disabled by default

With default u-boot configuration u-boot doesn't initialize the Display interface. This feature can be activated by deleting the "panel" environment variable. But also with deactivated display interface, the bootlaoder reads the display settings and pass the settings to the linux kernel.

panel="no_panel": Display interface is deactiveted in u-boot and backlight is powered off.
panel="RGB": Default DH 4,3" display is selected.
panel=deleted: u-boot initialize display by DH settings file.

Backlight enable GPIO

If ENV variable "panel" is set to "no_panel" the backlight enable GPIO (defined via DHCOM settings file or eeprom settings) will be disabled from the bootloader during startup.

If ENV variable "panel" is deleted, the backlight enable GPIO is activated or deactivated in relation to BL_ON flag of DHCOM settings file.

Note: Supported by U-Boot DH VERSION v0.4.2.5 or higher for iMX6

Building U-Boot

Prepare Build Environment

1. Download and start the Virtual Machine for Application Development

Get Sources

2. Start a terminal on Linux 3. # git clone https://github.com/dh-electronics/u-boot-imx6qdl.git 4. # cd u-boot-imx6qdl 5. # git checkout dev/legacy/2018.05_dhcom

Start Build

6. # make ARCH=arm CROSS_COMPILE=/opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf- dh_imx6_defconfig 7. # make ARCH=arm CROSS_COMPILE=/opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf- all

Your new u-boot-with-spl.imx file is available in u-boot-imx6qdl/

Building U-Boot (Version 2015.10 and older)

Prepare Build Environment

1. Download and start the Virtual Machine for Application Development

Get Sources

2. Start a terminal on Linux 3. # git clone https://github.com/dh-electronics/u-boot-imx6qdl.git 4. # cd u-boot-imx6qdl 5. # git checkout dev/legacy/2018.05_dhcom

Start Build

6. # make ARCH=arm CROSS_COMPILE=/opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf- dh_imx6_defconfig 7. # make ARCH=arm CROSS_COMPILE=/opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf- all

Your new u-boot-with-spl.imx file is available in u-boot-imx6qdl/