Torizon 5.0.0

Introduction

Linux Device Tree is a data structure describing a system's hardware.

Sometimes, it is necessary to modify the Device Tree. Some use cases that require Device Tree modifications include (but not limited to):

• Add a Display to the board and configure its pin and timing settings.
• Bring up a new peripheral connected to the SoM, for example, an external CAN transceiver connected through the SPI interface.
• Changing the SoC's pin functions, i.e., Pin Multiplexing, e.g., set the GPIO function for some specific pin not assigned to this function by default.

Device Tree is built with the Kernel when building the distribution. However, Device Tree Overlays provide a way to modify the overall device tree without the need for re-compiling the complete device tree.

Overlays are small pieces, or fragments, of a complete device tree, and can be added or removed as needed, often enabling/disabling hardware components in the system.

Due to its flexible nature, overlays provide an advantageous way of describing peripheral hardware added or removed from the system. It is also useful for tweaking the existing hardware parameters before committing it to a complete device tree. You can find rich information about overlays available on the web.

In a very brief description, the process of designing for a Device Tree Overlay comprises three macro steps:

1. Write a Device Tree Overlay (.dts) file.
2. Build the dts file
3. Enable the overlay

Device trees and overlays in human-readable format (dts files) must be compiled to binary format (dtb for complete device-trees, dtbo for overlays) to be parsed by the kernel.

This article will show the tools available for making and applying device tree overlays on Toradex SoMs that use TorizonCore as the operating system. If you want to use device tree overlays with our Reference Images for Yocto Project, read the Building the Device Tree Overlays section from Build U-Boot and Linux Kernel from Source Code.

There are different phases of development with different methods for customizing TorizonCore with device tree overlays:

• Evaluation and prototyping: you can modify the overlays.txt file directly in the device or apply an overlay in just one command with the TorizonCore Builder Tool.
• Development and production: you must use the TorizonCore Builder Tool.

This article complies to the Typographic Conventions for Torizon Documentation

Prerequisites

• A Toradex SoM with Torizon installed.
• A TorizonCore image downloaded.

Evaluation and Prototyping only: Quickly Enabling Displays, Touch Controllers, Adapters, and other Add-on Products Provided by Toradex

Attention: The instructions provided in this session are intended for prototype and proof-of-concept only. For production, skip directly to the next section of this article for information about TorizonCore Builder usage.

There are two possible approaches to quickly evaluate overlays on the device, by executing a TorizonCore Builder command or by changing the text of the overlays.txt file directly on the board.

Approach 1: Applying Device Tree Overlays to an Image Using a Single TorizonCore Builder Command

If you want to quickly test a device tree overlay, you can apply the overlay on a running device with a single TorizonCore Builder command. Behind the scenes, TorizonCore Builder will execute all the steps necessary to deploy an image to your device.

Before using this command, it is necessary to install TorizonCore Builder and have the source code of the desired overlays available in the working directory.

Additional prerequisites

• Prerequisites from Configure Build Environment for Torizon Containers installed.
• Having read the Torizoncore Builder - Getting Started article can be helpful.

Install TorizonCore Builder

To install TorizonCore Builder, click on the link below and follow the steps.

$ mkdir ~/tcbworkdir
$ cd ~/tcbworkdir

$ wget https://raw.githubusercontent.com/toradex/tcb-env-setup/master/tcb-env-setup.sh
$ source tcb-env-setup.sh

$ torizoncore-builder --help

Clone Toradex Device Tree and Overlays Repository

You just need to execute this once. In order to clone the right branch of the repository, you should first download an image and unpack it accordingly with your device.

If you have not unpacked an image yet, download a base TorizonCore image (preferably without containers) inside the TorizonCore Builder working directory, then run the command below to unpack it. In the example below the torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar image is used as a reference:

$ torizoncore-builder images unpack torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar

If you want to change the TorizonCore base image, download the new image and run the images unpack command again, passing the new image as the argument.

For more details about the images unpack command, please check the images unpack command in the commands manual.

Instead of using the images unpack you can use the images download command. This command checks which is the connected Toradex SoM, downloads the compatible latest quarterly release of a TorizonCore image without containers, and unpacks this image.

$ torizoncore-builder images download --remote-host 192.168.1.117 --remote-username torizon --remote-password torizon

Change the arguments --remote-host,--remote-username and --remote-password to your board IP Address, username and password, respectively.

For more details on how the images download command works, please check the images download command in the commands manual.

Then, to get the source code of the Toradex supplied device tree files (including overlays), one could use the command below:

$ torizoncore-builder dt checkout

Note: The dt checkout --update command can be used to update an already existing device trees and overlays folder.

For more details about the dt checkout command, please check the dt checkout command in the commands manual.

Select the Desired Overlay

Then to check the available overlays names for a particular device tree (imx6dl-colibri-eval-v3.dtb in this case), run the command below:

$ torizoncore-builder dto list --device-tree ./device-trees/dts-arm32/imx6dl-colibri-eval-v3.dts

Overlays compatible with device tree imx6dl-colibri-eval-v3.dts:
- device-trees/overlays/colibri-imx6_atmel-mxt-adapter_overlay.dts
- device-trees/overlays/colibri-imx6_atmel-mxt-connector_overlay.dts
- device-trees/overlays/colibri-imx6_hdmi_overlay.dts
- device-trees/overlays/colibri-imx6_parallel-rgb-lvds_overlay.dts
- device-trees/overlays/colibri-imx6_parallel-rgb_overlay.dts
- device-trees/overlays/colibri-imx6_stmpe-ts_overlay.dts
- device-trees/overlays/display-dpi-lt170410_overlay.dts
- device-trees/overlays/display-edt5.7_overlay.dts
- device-trees/overlays/display-edt7_overlay.dts
- device-trees/overlays/display-fullhd_overlay.dts
- device-trees/overlays/display-lt161010_overlay.dts
- device-trees/overlays/display-vga_overlay.dts

Apply the Overlay to the Image

To enable a display using the display-edt7_overlay.dts overlay, you will only need to run the following command:

$ torizoncore-builder dto deploy --remote-host 192.168.1.117 --remote-username torizon --remote-password torizon --force --reboot device-trees/overlays/display-edt7_overlay.dts

Change the arguments --remote-host,--remote-username and --remote-password to your board IP Address, username, and password, respectively.

For more details about the dto commands, please check the dto command in the commands manual.

Approach 2: Applying Device Tree Overlays to an Image Directly on the Device

On TorizonCore image there are pre-built Device Tree Overlays for Add-on Products available in Toradex's webshop. You can see a complete list of the available overlays at the end of this article.

First, get the hash of the current OSTree deployment with the command below:

cat /proc/cmdline
enable_wait_mode=off galcore.contiguousSize=50331648 root=LABEL=otaroot rootfstype=ext4 quiet logo.nologo vt.global_cursor_default=0 plymouth.ignore-serial-consoles splash ostree=/ostree/boot.0/torizon/4ed13802dd58a0bed6fe3fe64c02dc9a2c976e75941403d633418ae316be0ea7/0

See a list of available pre-built overlays (*.dtbo files):

# ls /sysroot/boot/ostree/torizon-4ed13802dd58a0bed6fe3fe64c02dc9a2c976e75941403d633418ae316be0ea7/dtb/overlays

To enable these overlays, you need to modify the file /sysroot/boot/ostree/torizon-*/dtb/overlays.txt in your SoM, adding the desired overlays. You can create it, if not existing.

This file will contain the string fdt_overlays= followed by a space-separated list of overlays.

For example, to enable the DSI to HDMI converter and the CSI Camera Module OV5640 on the Verdin iMX8M Mini module, use the following commands:

# cd /sysroot/boot/ostree/torizon-4ed13802dd58a0bed6fe3fe64c02dc9a2c976e75941403d633418ae316be0ea7/dtb/
# sudo sh -c "echo 'fdt_overlays=verdin-imx8mm_lt8912_overlay.dtbo verdin-imx8mm_ov5640_overlay.dtbo' > overlays.txt"
# sync

In this example, this will be the content of the overlays.txt file:

 /sysroot/boot/ostree/torizon-4ed13802dd58a0bed6fe3fe64c02dc9a2c976e75941403d633418ae316be0ea7/dtb/overlays.txt
fdt_overlays=verdin-imx8mm_lt8912_overlay.dtbo verdin-imx8mm_ov5640_overlay.dtbo

To enable the DSI to HDMI converter only, use the following command:

# sudo sh -c "echo 'fdt_overlays=verdin-imx8mm_lt8912_overlay.dtbo' > overlays.txt"
# sync

After changing the overlays.txt file, reboot the board. To do it, you can use the following command:

# sudo reboot

If you want to obtain the source code of the Device Tree Overlays provided by Toradex for the products available on the webshop, see the Clone Toradex Device Tree and Overlays Repository section of the prior approach.

Attention: If you add a device tree overlay that will break the kernel boot you can set the U-Boot environment variable skip_fdt_overlays to 1. In U-Boot do: setenv skip_fdt_overlays 1

Development and Production: Using TorizonCore Builder

The TorizonCore Builder Tool is the recommended method for customizing TorizonCore for development and production.

Additional prerequisites

• Prerequisites from Configure Build Environment for Torizon Containers installed.
• Having read the Torizoncore Builder - Getting Started article can be helpful.

Installing TorizonCore Builder

To install TorizonCore Builder, read our statements on OS and shell compatibility, then follow the instructions below, in order.

Create and enter a working directory where your customization will be stored:

$ mkdir ~/tcbworkdir
$ cd ~/tcbworkdir

Use the setup script named tcb-env-setup.sh, available on the Toradex Github, to setup TorizonCore Builder:

$ wget https://raw.githubusercontent.com/toradex/tcb-env-setup/master/tcb-env-setup.sh
$ source tcb-env-setup.sh

For advanced usage, run source tcb-env-setup.sh -h, or see the project README.

If using Windows, you must pass extra parameters to the script when using the following commands:

• ostree serve: consult the ostree serve reference.

Tip: The setup script installs a bash completion script for TorizonCore Builder, making it possible to autocomplete commands and parameters by just pressing the TAB key.

Verify that the command torizoncore-builder is available:

$ torizoncore-builder --help

Warning: Make sure to: (1) source the script, (2) every time you open a new terminal, (3) inside the working directory you have previously created. Otherwise, it will not work as intended and, most importantly, the torizoncore-builder alias will not be created properly.

Writing a Device Tree Overlay

The most recommended way to create a new overlay is to start looking at similar overlays and then adapt to your project's needs. The next chapters of this article will show how you can obtain Device Tree Overlays source files for peripherals sold by Toradex.

However, if you need to build overlays for different hardware, the Linux Kernel source provides binding documentation for specific peripherals.

To access this information, visit The Linux Kernel Archives website and browse the Linux Kernel source for your board's specific version. You will find the particular bindings information in the Linux kernel source at the Documentation/devicetree/bindings directory.

As an example, you can look at the binding documentation for the version v4.14.184.

To find out the Linux Kernel version on your board, type on the board's Linux terminal:

# uname -r

Applying Device Trees and Overlays to a Custom Image

There are two possible approaches to apply the customization and generate a custom Toradex Easy Installer image, described in the next two sections Approach 1 and Approach 2. These approaches in some cases are interchangeable and in some not as described in the next sections.

To learn about TorizonCore Builder workflow and the different approaches to use the tool, with explanatory diagrams, please refer to the TorizonCore Builder - Workflow article.

Attention: Both approaches generate a custom Toradex Easy Installer image as output, so the approaches should be followed alternatively and not in sequence.

Approach 1: Applying a Device Tree and Device Tree Overlays to a Custom Image Using the Build Command

TorizonCore Builder build command generates a custom TorizonCore image with the specified device-tree and overlays, ready to be installed with Toradex Easy Installer, named torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM in the example below. This is achieved using a configuration YAML file, tcbuild.yml as default.

This is the recommended approach on production programming and on CI/CD (continuous integration / continuous development) pipelines.

To learn about TorizonCore Builder workflow and the different approaches to use the tool, with explanatory diagrams, please refer to the TorizonCore Builder - Workflow article.

It requires a Toradex Easy Installer image of TorizonCore (preferably without containers), torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar in this case, as input. The device-tree is passed as customization: device-tree: custom:, also passing the directory containing the files included in the device tree (defined with #include in the source code) as customization: device-tree: include-dirs:. Each overlay is passed as customization: device-tree: overlays: add:.

 tcbuild.yaml
# Sample configuration file:
input:
  easy-installer:
    local: images/torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar
#Sample customization: insert the resistive 7" display overlay in the IMX6 device-tree with Aster Carrier Board
customization:
  device-tree:
    include-dirs:
      - device-trees/include/
    custom: device-trees/dts-arm32/imx6dl-colibri-eval-v3.dts
    overlays:
      add:
        - device-trees/overlays/display-edt7_overlay.dts
output:
  easy-installer:
    local: torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM

The files containing the source code of the device trees and overlays should be available before running the build command. To get the source code of the Toradex supplied device-tree files (including overlays), please refer to the next section. Also, to see how to write your own device tree overlay, please refer to the Writing a Device Tree Overlay section.

Clone The Toradex Repository and Check The Available Device Trees and Overlays

Toradex provides source files of Device Trees and Device Tree Overlays for the add-on products available in the webshop. For information about these overlays, see the Toradex Device Tree Overlays repository on Github and the Setting up Displays with Torizon article.

You just need to execute this once. In order to clone the right branch of the repository, you should first download an image and unpack it accordingly with your device.

If you have not unpacked an image yet, download a base TorizonCore image (preferably without containers) inside the TorizonCore Builder working directory, then run the command below to unpack it. In the example below the torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar image is used as a reference:

$ torizoncore-builder images unpack torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar

If you want to change the TorizonCore base image, download the new image and run the images unpack command again, passing the new image as the argument.

For more details about the images unpack command, please check the images unpack command in the commands manual.

Instead of using the images unpack you can use the images download command. This command checks which is the connected Toradex SoM, downloads the compatible latest quarterly release of a TorizonCore image without containers, and unpacks this image.

$ torizoncore-builder images download --remote-host 192.168.1.117 --remote-username torizon --remote-password torizon

Change the arguments --remote-host,--remote-username and --remote-password to your board IP Address, username and password, respectively.

For more details on how the images download command works, please check the images download command in the commands manual.

Then, to get the source code of the Toradex supplied device tree files (including overlays), one could use the command below:

$ torizoncore-builder dt checkout

For more details about the dt checkout command, please check the dt checkout command in the commands manual.

To see the available device trees and select the appropriate one for your device, run the command below, passing the parameter -name accordingly to your device.

• Apalis iMX6
• Apalis iMX8
• Apalis iMX8X
• Colibri iMX6
• Colibri iMX7
• Colibri iMX8X
• Verdin iMX8M Mini
• Verdin iMX8M Plus

$ find device-trees/dts-arm32 -name "*imx6q-apalis*.dts"

device-trees/dts-arm32/imx6q-apalis-ixora-v1.2.dts
device-trees/dts-arm32/imx6q-apalis-ixora.dts
device-trees/dts-arm32/imx6q-apalis-ixora-v1.1.dts
device-trees/dts-arm32/imx6q-apalis-eval.dts

$ find device-trees/dts-arm64 -name "*imx8qp-apalis*.dts" # for Apalis iMX8 QuadPlus versions
$ find device-trees/dts-arm64 -name "*imx8qm-apalis*.dts" # for Apalis iMX8 QuadMax versions

device-trees/dts-arm64/imx8qp-apalis-v1.1-ixora-v1.1.dts
device-trees/dts-arm64/imx8qp-apalis-v1.1-eval.dts
device-trees/dts-arm64/imx8qm-apalis-eval.dts
device-trees/dts-arm64/imx8qm-apalis-ixora-v1.1.dts
device-trees/dts-arm64/imx8qm-apalis-v1.1-eval.dts
device-trees/dts-arm64/imx8qm-apalis-v1.1-ixora-v1.1.dts

$ find device-trees/dts-arm64 -name "*imx8qxp-apalis*.dts"

device-trees/dts-arm64/imx8qxp-apalis-v1.1-eval.dts

$ find device-trees/dts-arm32 -name "*imx6dl-colibri*.dts"

device-trees/dts-arm32/imx6dl-colibri-eval-v3.dts

$ find device-trees/dts-arm32 -name "*imx7d-colibri*.dts"

device-trees/dts-arm32/imx7d-colibri-aster.dts
device-trees/dts-arm32/imx7d-colibri-emmc-eval-v3.dts
device-trees/dts-arm32/imx7d-colibri-emmc-aster.dts
device-trees/dts-arm32/imx7d-colibri-eval-v3.dts

$ find device-trees/dts-arm64 -name "*imx8qxp-colibri*.dts"

device-trees/dts-arm64/imx8qxp-colibri-aster.dts
device-trees/dts-arm64/imx8qxp-colibri-dsihdmi-eval-v3.dts
device-trees/dts-arm64/imx8qxp-colibri-eval-v3.dt

$ find device-trees/dts-arm64 -name "*imx8mm-verdin*.dts"

device-trees/dts-arm64/imx8mm-verdin-nonwifi-dev.dts
device-trees/dts-arm64/imx8mm-verdin-wifi-dev.dts
device-trees/dts-arm64/imx8mm-verdin-wifi-dahlia.dts
device-trees/dts-arm64/imx8mm-verdin-nonwifi-dahlia.dts

$ find device-trees/dts-arm64 -name "*imx8mp-verdin*.dts"

device-trees/dts-arm64/imx8mp-verdin-wifi-dahlia.dts
device-trees/dts-arm64/imx8mp-verdin-nonwifi-dahlia.dts
device-trees/dts-arm64/imx8mp-verdin-nonwifi-dev.dts
device-trees/dts-arm64/imx8mp-verdin-wifi-dev.dts

Then to check the available overlays names for a particular device tree (imx6dl-colibri-eval-v3.dtb in this case), run the command below:

$ torizoncore-builder dto list --device-tree ./device-trees/dts-arm32/imx6dl-colibri-eval-v3.dts

Overlays compatible with device tree imx6dl-colibri-eval-v3.dts:
- device-trees/overlays/colibri-imx6_atmel-mxt-adapter_overlay.dts
- device-trees/overlays/colibri-imx6_atmel-mxt-connector_overlay.dts
- device-trees/overlays/colibri-imx6_hdmi_overlay.dts
- device-trees/overlays/colibri-imx6_parallel-rgb-lvds_overlay.dts
- device-trees/overlays/colibri-imx6_parallel-rgb_overlay.dts
- device-trees/overlays/colibri-imx6_stmpe-ts_overlay.dts
- device-trees/overlays/display-dpi-lt170410_overlay.dts
- device-trees/overlays/display-edt5.7_overlay.dts
- device-trees/overlays/display-edt7_overlay.dts
- device-trees/overlays/display-fullhd_overlay.dts
- device-trees/overlays/display-lt161010_overlay.dts
- device-trees/overlays/display-vga_overlay.dts

The repository contains device tree source files and device tree overlays, which have the .dts extension, and .dtsi and .h files. Also, it has the following directory organization:

• dts-arm32 - source files of device trees for Toradex modules of 32-bit architectures.
• dts-arm64 - source files of device trees for Toradex modules of 64-bit architectures.
• overlays - source files of device tree overlays for Toradex modules.

Keep in mind that every time you start working on a new directory the repository will need to be cloned again. A recommended solution to this problem, if your project where you have the configuration YAML file is on a Git repository, would be to create a git submodule inside your repository pointing to the Toradex Device Tree and Overlays Repository.

Build The Custom Image

To generate the TorizonCore image, run the command below, in the same directory where the tcbuild.yaml file is:

$ torizoncore-builder build

...
1091 metadata, 12741 content objects imported; 412.2 MB content written                                                                                                                                   
Pulling done.
Deploying OSTree with checksum 58629613a342197c31c5911d0874aac1b0fcb46b68a63f59760c03bacc4df08a
Deploying done.
Copy files not under OSTree control from original deployment.
Packing rootfs...
Packing rootfs done.

=>> Build command successfully executed!

In case of using a configuration file with a different name than tcbuild.yaml, run the command specifying the configuration file name:

$ torizoncore-builder build --file <configuration_file_name>

Deploy The Custom Toradex Easy Installer Image

To deploy the custom Toradex Easy Installer image to the board, click on the link below and choose between the available options.

$ cp -a torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM /media/user/myUSBstick

$ torizoncore-builder images unpack torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM

$ torizoncore-builder deploy --remote-host 192.168.1.117 --remote-username torizon --remote-password torizon --reboot

$ torizoncore-builder images unpack torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM

$ torizoncore-builder platform push --credentials credentials.zip --package-name base-package --package-version base-package-1.0 base

Approach 2: Applying a Device Tree and Device Tree Overlays to a Custom Image Using Standalone Commands

In this second approach, instead of using a configuration YAML file and a one-step command, the generation of the custom TorizonCore with the device tree and overlays is done using standalone commands, each performing one step towards this generation.

This approach is especially useful when making incremental changes, generating multiple images with different device tree overlays (or other customizations like different external kernel modules). As you will see, applying a device tree or including a device tree overlay on an image of TorizonCore that has other customizations (including other device tree overlays) is just a matter of performing the apply, merge and deploy stages.

To learn about TorizonCore Builder workflow and the different approaches to use the tool, with explanatory diagrams, please refer to the TorizonCore Builder - Workflow article.

To generate a custom Toradex Easy Installer image with the desired device tree and overlays follow the sequence of steps below.

Unpack an Input Image

You just need to execute this once. Then, you are ready to apply multiple changes to the image. For example, in addition to applying a new device tree or different overlays, you can also apply an external kernel module, a new splash screen, among other possibilities.

If you have not unpacked an image yet, download a base TorizonCore image (preferably without containers) inside the TorizonCore Builder working directory, then run the command below to unpack it. In the example below the torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar image is used as a reference:

$ torizoncore-builder images unpack torizon-core-docker-colibri-imx6-Tezi_5.3.0+build.7.tar

If you want to change the TorizonCore base image, download the new image and run the images unpack command again, passing the new image as the argument.

For more details about the images unpack command, please check the images unpack command in the commands manual.

Instead of using the images unpack you can use the images download command. This command checks which is the connected Toradex SoM, downloads the compatible latest quarterly release of a TorizonCore image without containers, and unpacks this image.

$ torizoncore-builder images download --remote-host 192.168.1.117 --remote-username torizon --remote-password torizon

Change the arguments --remote-host,--remote-username and --remote-password to your board IP Address, username and password, respectively.

For more details on how the images download command works, please check the images download command in the commands manual.

Clone the Toradex Device Tree and Overlays Repository with dt checkout

You just need to execute this once. This does the same as Clone The Toradex Repository of Approach 1. However, as you have already unpacked the right image for your device, you do not need to worry about the branch that will be cloned. You simply need to run the dt checkout command below.

$ torizoncore-builder dt checkout

The repository contains device tree source files and device tree overlays, which have the .dts extension, and .dtsi and .h files. Also, it has the following directory organization:

• dts-arm32 - source files of device trees for Toradex modules of 32-bit architectures.
• dts-arm64 - source files of device trees for Toradex modules of 64-bit architectures.
• overlays - source files of device tree overlays for Toradex modules.

Note: The dt checkout --update command can be used to update an already existing device trees and overlays folder.

For more details about the dt checkout command, please check the dt checkout command in the commands manual.

Compile and Apply a Device Tree

To identify the current device tree of the image, use the following command:

$ torizoncore-builder dt status

Current device tree is: imx6q-apalis-eval.dtb

In the above command, note that the device tree has the .dtb extension, meaning that it's a compiled device tree.

Note: Some images of Toradex modules don't set the device tree upfront, delaying the selection of a device tree for boot time. In these cases, dt status won't be able to show the current device tree of the image.

To compile a given device tree source file and then set it to be used in the image, use the following command:

$ torizoncore-builder dt apply device-trees/dts-arm32/imx6q-apalis-ixora-v1.1.dts

Note: When applying a device tree with dt apply, all overlays that were eventually applied are reset.

For more details about the dt commands, please check the dt command in the commands manual.

Compile and Apply Device Tree Overlays

To list the overlays under device-trees/overlays that are compatible with the current device tree, use dto list:

$ torizoncore-builder dto list

Overlays compatible with device tree imx6q-apalis-ixora-v1.1.dtb:
- device-trees/overlays/apalis-imx6_atmel-mxt_overlay.dts
- device-trees/overlays/apalis-imx6_hdmi_overlay.dts
- device-trees/overlays/apalis-imx6_lcd_overlay.dts
- device-trees/overlays/apalis-imx6_lvds_overlay.dts
- device-trees/overlays/apalis-imx6_stmpe-ts_overlay.dts
- device-trees/overlays/apalis-imx6_vga_overlay.dts
- device-trees/overlays/display-edt5.7_overlay.dts
- device-trees/overlays/display-edt7_overlay.dts
- device-trees/overlays/display-fullhd_overlay.dts
- device-trees/overlays/display-lt161010_overlay.dts
- device-trees/overlays/display-lt170410_overlay.dts

To compile a given device tree overlay source file and then set it to be applied to the device tree during boot, use dto apply:

$ torizoncore-builder dto apply device-trees/overlays/apalis-imx6_hdmi_overlay.dts

In the above example:

1. The device tree overlay source apalis-imx6_hdmi_overlay.dts was successfully compiled to apalis-imx6_hdmi_overlay.dtbo.
2. For testing, the compiled overlay apalis-imx6_hdmi_overlay.dtbo modified successfully a temporary copy of the current device tree imx6q-apalis-ixora-v1.1.dtb. This is just a sanity verification that the overlay won't fail when applied during booting the module. This step can be bypassed with option --force to dto apply.
3. On successful execution of the previous steps, the compiled overlay was added to the list of overlays that are applied to the current device tree of the module during boot.

Overlays can be applied incrementally; if you want to enable more overlays, use dto apply again.

To identify the device tree overlays that are currently applied to the device tree in the image, use dto status:

$ torizoncore-builder dto status

Enabled overlays over device tree imx6q-apalis-ixora-v1.1.dtb:
- apalis-imx6_hdmi_overlay.dtbo

In the above example, note that the overlays have the .dtbo extension, meaning they are compiled files.

For more details about the dto commands, please check the dto command in the commands manual.

Remove Device Tree Overlays

To remove an applied overlay, use dto remove and pass the overlay blob name as given by dt status in the section above:

$ torizoncore-builder dto remove apalis-imx6_hdmi_overlay.dtbo

For more details about the dto remove commands, please check the dto remove command in the commands manual.

Merge Changes

Merge the new device tree and the different overlays (as well as other customizations like an external kernel module or a new splash screen) into the base Toradex Easy Installer image of TorizonCore - use whatever branch name you want.

As an example, to commit changes into a branch named custom-branch use the command below, accordingly with the TorizonCore Builder version:

• Versions 3.0.0 or Later
• Versions Before 3.0.0

$ torizoncore-builder union custom-branch

Applying changes from STORAGE/dt.
Commit 58629613a342197c31c5911d0874aac1b0fcb46b68a63f59760c03bacc4df08a has been generated for changes and is ready to be deployed.

$ torizoncore-builder union --union-branch=custom-branch

Warning: We recommend that you switch to the latest version of TorizonCore Builder to enjoy its simpler and more consistent user interface besides other improvements and bug fixes.

For more details about the union command, please check the union command in the commands manual.

Deploy The Custom Toradex Easy Installer Image

To deploy the custom Toradex Easy Installer image to the board, click on the link below and choose between the available options.

$ torizoncore-builder deploy custom-branch --output-directory torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM

$ cp -a torizon-core-docker-colibri-imx6-Tezi_5.3.0.CUSTOM /media/user/myUSBstick

$ torizoncore-builder deploy custom-branch --remote-host 192.168.1.117 --remote-username torizon --remote-password torizon --reboot

$ torizoncore-builder push --credentials credentials.zip custom-branch

Verifying The New Custom Image On The Device

After rebooting, in your target device's terminal, verify that your new custom image of TorizonCore is active on the device with the command below:

# sudo ostree admin status

Password: 
* torizon 58629613a342197c31c5911d0874aac1b0fcb46b68a63f59760c03bacc4df08a.0
    Version: 5.3.0+build.7-tcbuilder.20211008140217
    origin refspec: tcbuilder:58629613a342197c31c5911d0874aac1b0fcb46b68a63f59760c03bacc4df08a
  torizon 36ad904617b170339b6ded7b9dce87ed8cf0f76473b897fdd832d91e82eb1ddc.0 (rollback)
    Version: 5.3.0+build.7
    origin refspec: tcbuilder:36ad904617b170339b6ded7b9dce87ed8cf0f76473b897fdd832d91e82eb1ddc

Where 58629613a342197c31c5911d0874aac1b0fcb46b68a63f59760c03bacc4df08a is the OSTree commit hash and should be the same as:

• The one in the output of the union command in the case of the standalone commands
• The one in the "Deploying OSTree with checksum ..." part of the output of the build command.

Rollback Mechanism

In case you find yourself with a non-working kernel (usually stuck at the "Loading kernel..." message) when applying a device tree overlay with TorizonCore Builder, after a few boot tries (3 by default), the system will roll back to the previous version of the operating system. For more information on the rollback mechanism, please refer to Update Rollbacks.

Device Tree Overlays Examples

Device tree examples, including overlays, can be found on Device Tree Customization Examples. See a list of remarkable examples available:

Some examples are available in other articles:

Note: at the moment, there are no device tree overlay examples outside the Device Tree Customization Examples.

List of Device Tree Overlays available for Add-on Products Provided by Toradex

Toradex provides Device Tree Overlays for the add-on products available in the webshop. For information about these overlays, see the Toradex Device Tree Overlays repository on Github and the Setting up Displays with Torizon article.

Displays

Attention: the migration to device tree overlays is currently a work-in-progress. There are some overlays or carrier board-specific device trees listed in the table below that are missing. For more information, please consult the BSP Layers and Reference Images for Yocto Project Issue Tracker.

• Capacitive Touch Display 7" Parallel
• Capacitive Touch Display 10.1" LVDS
• Resistive Touch Display 7" Parallel
• HDMI
• VGA
• EDT 7.0" (EOL)

Pre-enabled Device Tree Overlays

Toradex turns on a pre-set of Device Tree Overlays to support the default display interfaces and panels.

• Apalis
• Colibri
• Verdin

RTC

DSI to HDMI Adapter