Debian: Getting Started with the PICO-PI-IMX7

Embedded Linux Guides
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This is a page about the Freescale based i.MX7; PICO-PI-IMX7.

Availability

Boards:

Vendor Documentation

Basic Requirements

imx_usb_loader

imx_usb_loader – USB & UART loader for i.MX5/6/7/8 series:
This project will need the build-essential and libusb-1.0-0-dev package from Debian/Ubuntu repo’s installed. Source: https://github.com/boundarydevices/imx_usb_loader
Download/build:

#user@localhost:~$
git clone https://github.com/boundarydevices/imx_usb_loader
cd imx_usb_loader/
make

ARM Cross Compiler: GCC

This is a pre-built (64bit) version of GCC that runs on generic linux, sorry (32bit) x86 users, it’s time to upgrade…
Download/Extract:

#user@localhost:~$
wget -c https://releases.linaro.org/components/toolchain/binaries/6.5-2018.12/arm-linux-gnueabihf/gcc-linaro-6.5.0-2018.12-x86_64_arm-linux-gnueabihf.tar.xz
tar xf gcc-linaro-6.5.0-2018.12-x86_64_arm-linux-gnueabihf.tar.xz
export CC=`pwd`/gcc-linaro-6.5.0-2018.12-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-

Test Cross Compiler:

#user@localhost:~$
${CC}gcc --version

#Test Output:
arm-linux-gnueabihf-gcc (Linaro GCC 6.5-2018.12) 6.5.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Bootloader: U-Boot

Das U-Boot – the Universal Boot Loader: http://www.denx.de/wiki/U-Boot
Depending on your Linux Distrubution, you will also need a host gcc and other tools, so with Debian/Ubuntu start with installing the build-essential meta package.
Download:

#user@localhost:~$
git clone -b v2021.10 https://github.com/u-boot/u-boot --depth=1
cd u-boot/

Configure and Build:

#user@localhost:~/u-boot$
make ARCH=arm CROSS_COMPILE=${CC} distclean
make ARCH=arm CROSS_COMPILE=${CC} pico-pi-imx7d_defconfig
make ARCH=arm CROSS_COMPILE=${CC}

Bootloader: imx-usb-loader

Place the board into USB boot mode, setting these Jumpers:
PICO-PI-IMX7-USB-Boot
Power Board and Check lsusb:

#user@localhost:~/u-boot$
lsusb | grep Freescale
Bus 00x Device 00y: ID 15a2:0076 Freescale Semiconductor, Inc
#or in newer Distributions:
Bus 00x Device 00y: ID 15a2:0076 Freescale Semiconductor, Inc. i.MX 7Solo/7Dual SystemOnChip in RecoveryMode

Load the SPL binary via USB:

#user@localhost:~/u-boot$
sudo ~/imx_usb_loader/imx_usb SPL

Verify imx_usb copied SPL to Device over USB:

#SERIAL_CONSOLE
U-Boot SPL 2021.10 (Jan 11 2022 - 15:35:38 -0600)
Trying to boot from USB SDP
SDP: initialize...
SDP: handle requests...

Load the u-boot-dtb.img binary via USB:

#user@localhost:~/u-boot$
sudo ~/imx_usb_loader/imx_usb u-boot-dtb.img

Using any key, break into U-Boot Console:

#SERIAL_CONSOLE_U_BOOT
Downloading file of size 509388 to 0x877fffc0... done
Jumping to header at 0x877fffc0
Header Tag is not an IMX image
Found header at 0x877fffc0

U-Boot 2021.10 (Jan 11 2022 - 15:35:38 -0600)

CPU:   Freescale i.MX7D rev1.2 1000 MHz (running at 792 MHz)
CPU:   Commercial temperature grade (0C to 95C) at 46C
Reset cause: POR
Model: TechNexion PICO-IMX7D Board and PI baseboard
Board: i.MX7D PICOSOM
I2C:   ready
DRAM:  512 MiB
PMIC:  PFUZE3000 DEV_ID=0x30 REV_ID=0x11
MMC:   FSL_SDHC: 3, FSL_SDHC: 1, FSL_SDHC: 0
Loading Environment from MMC... OK
In:    serial
Out:   serial
Err:   serial
Net:   eth0: ethernet@30be0000
Hit any key to stop autoboot:  0 
=>

Use the default environment variables:

#SERIAL_CONSOLE_U_BOOT
=> env default -a
=> setenv bootm_boot_mode nonsec
=> saveenv

Configure mmc 0 to boot from the data partition, and disable access to boot partitions:

#SERIAL_CONSOLE_U_BOOT
=> mmc partconf 0 0 7 0

enable U-Boot USB Mass Storage mode:

#SERIAL_CONSOLE_U_BOOT
=> ums 0 mmc 0

Verify Linux loaded the USB Mass Storage device, this will be the SD Card used thru out this wiki:

#user@localhost:~/u-boot$
lsusb | grep Netchip
Bus 00x Device 00y: ID 0525:a4a5 Netchip Technology, Inc. Pocketbook Pro 903

Linux Kernel

This script will build the kernel, modules, device tree binaries and copy them to the deploy directory.
Download:

#user@localhost:~$
git clone https://github.com/RobertCNelson/armv7-lpae-multiplatform ./kernelbuildscripts
cd kernelbuildscripts/

For v5.10.x (Longterm 5.10.x):

#user@localhost:~/kernelbuildscripts$
git checkout origin/v5.10.x -b tmp

For v5.15.x (Longterm 5.15.x):

#user@localhost:~/kernelbuildscripts$
git checkout origin/v5.15.x -b tmp

Build:

#user@localhost:~/kernelbuildscripts$
./build_kernel.sh

Root File System

Debian 11

User Password
debian temppwd
root root

Download:

#user@localhost:~$
wget -c https://rcn-ee.com/rootfs/eewiki/minfs/debian-11.3-minimal-armhf-2022-04-15.tar.xz

Verify:

#user@localhost:~$
sha256sum debian-11.3-minimal-armhf-2022-04-15.tar.xz

#sha256sum output:
575738843651de2962f251447f4742d4f33313d6f7f5edf282a401207f5e6646  debian-11.3-minimal-armhf-2022-04-15.tar.xz

Extract:

#user@localhost:~$
tar xf debian-11.3-minimal-armhf-2022-04-15.tar.xz

Setup microSD card

We need to access the External Drive to be utilized by the target device. Run lsblk to help figure out what linux device has been reserved for your External Drive.

#Example: for DISK=/dev/sdX
lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk
├─sda1   8:1    0   512M  0 part /boot/efi
└─sda2   8:2    0 465.3G  0 part /                <- Development Machine Root Partition
sdb      8:16   1   962M  0 disk                  <- microSD/USB Storage Device
└─sdb1   8:17   1   961M  0 part                  <- microSD/USB Storage Partition

#Thus you would use:
export DISK=/dev/sdb

#Example: for DISK=/dev/mmcblkX
lsblk
NAME      MAJ:MIN   RM   SIZE RO TYPE MOUNTPOINT
sda         8:0      0 465.8G  0 disk
├─sda1      8:1      0   512M  0 part /boot/efi
└─sda2      8:2      0 465.3G  0 part /                <- Development Machine Root Partition
mmcblk0     179:0    0   962M  0 disk                  <- microSD/USB Storage Device
└─mmcblk0p1 179:1    0   961M  0 part                  <- microSD/USB Storage Partition

#Thus you would use:
export DISK=/dev/mmcblk0

Erase partition table/labels on microSD card:

sudo dd if=/dev/zero of=${DISK} bs=1M count=10

Install Bootloader:

#user@localhost:~$
sudo dd if=./u-boot/SPL of=${DISK} seek=1 bs=1k
sudo dd if=./u-boot/u-boot-dtb.img of=${DISK} seek=69 bs=1k

Create Partition Layout:
With util-linux v2.26, sfdisk was rewritten and is now based on libfdisk.

#Check the version of sfdisk installed on your pc is atleast 2.26.x or newer.
sudo sfdisk --version

#Example Output
sfdisk from util-linux 2.27.1

#sfdisk >= 2.26.x
sudo sfdisk ${DISK} <<-__EOF__
1M,,L,*
__EOF__

Format Partition:

for: DISK=/dev/mmcblkX
sudo mkfs.ext4 -L rootfs ${DISK}p1
 
for: DISK=/dev/sdX
sudo mkfs.ext4 -L rootfs ${DISK}1

Mount Partition:
On most systems these partitions may be auto-mounted…

sudo mkdir -p /media/rootfs/
 
for: DISK=/dev/mmcblkX
sudo mount ${DISK}p1 /media/rootfs/
 
for: DISK=/dev/sdX
sudo mount ${DISK}1 /media/rootfs/

Install Kernel and Root File System

To help new users, since the kernel version can change on a daily basis. The kernel building scripts listed on this page will now give you a hint of what kernel version was built.

-----------------------------
Script Complete
eewiki.net: [user@localhost:~$ export kernel_version=5.X.Y-Z]
-----------------------------

Copy and paste that “export kernel_version=5.X.Y-Z” exactly as shown in your own build/desktop environment and hit enter to create an environment variable to be used later.

export kernel_version=5.X.Y-Z

Copy Root File System

#Debian; Root File System: user@localhost:~$
sudo tar xfvp ./debian-*-*-armhf-*/armhf-rootfs-*.tar -C /media/rootfs/
sync

Setup extlinux.conf

#user@localhost:~$
sudo mkdir -p /media/rootfs/boot/extlinux/
sudo sh -c "echo 'label Linux ${kernel_version}' > /media/rootfs/boot/extlinux/extlinux.conf"
sudo sh -c "echo '    kernel /boot/vmlinuz-${kernel_version}' >> /media/rootfs/boot/extlinux/extlinux.conf"
sudo sh -c "echo '    append root=/dev/mmcblk2p1 ro rootfstype=ext4 rootwait quiet' >> /media/rootfs/boot/extlinux/extlinux.conf"
sudo sh -c "echo '    fdtdir /boot/dtbs/${kernel_version}/' >> /media/rootfs/boot/extlinux/extlinux.conf"

Copy Kernel Image

Kernel Image:

#user@localhost:~$
sudo cp -v ./kernelbuildscripts/deploy/${kernel_version}.zImage /media/rootfs/boot/vmlinuz-${kernel_version}

Copy Kernel Device Tree Binaries

#user@localhost:~$
sudo mkdir -p /media/rootfs/boot/dtbs/${kernel_version}/
sudo tar xfv ./kernelbuildscripts/deploy/${kernel_version}-dtbs.tar.gz -C /media/rootfs/boot/dtbs/${kernel_version}/

Copy Kernel Modules

#user@localhost:~$
sudo tar xfv ./kernelbuildscripts/deploy/${kernel_version}-modules.tar.gz -C /media/rootfs/

File Systems Table (/etc/fstab)

#user@localhost:~/$
sudo sh -c "echo '/dev/mmcblk2p1  /  auto  errors=remount-ro  0  1' >> /media/rootfs/etc/fstab"

WiFi AP6335

#user@localhost:~$
wget -c https://raw.githubusercontent.com/buildroot/buildroot/master/board/technexion/imx7dpico/rootfs_overlay/lib/firmware/brcm/brcmfmac4339-sdio.txt
sudo mkdir -p /media/rootfs/lib/firmware/brcm/
sudo cp -v ./brcmfmac4339-sdio.txt /media/rootfs/lib/firmware/brcm/

Status:

debian@arm:~$ dmesg | grep brcm
[   17.000227] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac4339-sdio for chip BCM4339/2
[   17.014290] usbcore: registered new interface driver brcmfmac
[   17.032649] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac4339-sdio.technexion,imx7d-pico-pi.txt failed with error -2
[   17.265035] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac4339-sdio for chip BCM4339/2
[   17.277324] brcmfmac: brcmf_c_process_clm_blob: no clm_blob available (err=-2), device may have limited channels available
[   17.290080] brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM4339/2 wl0: Feb 17 2016 18:29:33 version 6.37.32.RC23.34.42 (r608406)
 
debian@arm:~$ sudo ifconfig -a wlan0
wlan0: flags=-28669<UP,BROADCAST,MULTICAST,DYNAMIC>  mtu 1500
        ether 28:ed:e0:02:64:10  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Remove microSD/SD card

sync
sudo umount /media/rootfs

Stop U-Boot USB Mass Storage mode, with CTRL-C, and reset the board:

#SERIAL_CONSOLE_U_BOOT
Loading Environment from MMC... OK
In:    serial
Out:   serial
Err:   serial
Net:   FEC0
Hit any key to stop autoboot:  0 
=> ums 0 mmc 0
UMS: LUN 0, dev0, hwpart 0, section 0x0, count 0x720000
Ctrl+C to exit ...
=> reset

Remove power and place the board back into eMMC boot mode, setting these Jumpers:
emmcBoot

Comments

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