NVIDIA Jetson - Device Tree Overlay: Difference between revisions

NVIDIA Jetson - Device Tree Overlay (view source)

Revision as of 22:54, 16 February 2022

1,609 bytes added , 16 February 2022

→‎Create a device tree overlay

Mleiva

214

edits

@@ Line 12: / Line 12: @@
 ===Device tree overlay structure===
+A device tree overlay for a hardware module must define the property:
+* '''fragment''': A DT overlay comprises a number of fragments, each of which targets one node and its subnodes.
+* '''overlay-name''': which specifies a name for the hardware module.
+* '''jetson-header-name''': which specifies the expansion header with which the hardware module is associated; must specify one of the values described in the table [https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/hw_setup_jetson_io.html#wwpID0E03B0HA jetson-header-name property values].
+* '''compatible''': which indicates which combination of Jetson module and carrier board the overlay supports; must specify one or more of the values described in the table [https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/hw_setup_jetson_io.html#wwpID0E03B0HA compatible property values].
-Fragments
+===Creating a Simple Device Tree Overlay===
-A DT overlay comprises a number of fragments, each of which targets one node and its subnodes. Although the concept sounds simple enough, the syntax seems rather strange at first:
-A device tree overlay for a hardware module must define the property:
+To create a simple device tree overlay to add a new custom property for Jetson Xavier NX Developer Kit  and attach it to the 40‑pin expansion header, create a file named my-overlay.dts on the target platform with the following contents:
-* '''overlay-name''': which specifies a name for the hardware module; a unique name that distinguishes this overlay from others.
-* '''jetson-header-name''': which specifies the expansion header with which the hardware module is associated; must specify one of the values described, depending on which header the hardware module is associated with
+<source lang="c">
-* '''compatible''': which indicates which combination of Jetson module and carrier board the overlay supports; must specify one or more of the values described below, depending on what Jetson platforms are supported
+/dts-v1/;
+/plugin/;
+/ {
+    overlay-name = "My Jetson Overlay Example";
+    jetson-header-name = "Jetson 40pin Header";
+    compatible = "nvidia,p3509-0000+p3668-0001";
+    fragment@0 {
+        target-path = "/";
+        __overlay__ {
+            my-custom-property = "This Is My Overlay";
+        };
+    };
+};
+</source>
+Enter the following command to compile the DTS source file into an overlay file:
+<source lang="bash">
+$ dtc -O dtb -o my-overlay.dtbo -@ my-overlay.dts
+</source>
+After you copy the new overlay file to the /boot directory, Jetson‑IO finds the overlay file and allows you to apply it, If you use an incorrect compatible value, the files is not listed
+<source lang="bash">
+$ sudo cp my-overlay.dtbo /boot
+$ sudo /opt/nvidia/jetson-io/config-by-hardware.py -l
+</source>
+Configuration listed from Xavier NX
+<source lang="bash">
+Configurations for the following hardware modules are available:
+. Adafruit SPH0645LM4H
+. FE-PI Audio V1 and Z V2
+. My Jetson Overlay example
+. ReSpeaker 4 Mic Array
+</source>
+Apply the device tree overlay created
+<source lang="bash">
+$ sudo /opt/nvidia/jetson-io/config-by-hardware.py -n "My Jetson Overlay example"
+</source>
 Support for hardware modules is handled by device tree overlay files (.dtbo files).