# Device tree file description

***Copyright © Quectel Wireless Solutions Co., Ltd. 2026. All rights reserved.***

---

# Overview

This document introduces the device tree file structure, location, and modification methods for the Quectel Pi H1 platform. Device tree is a data structure used by the Linux kernel to describe hardware configuration. Understanding the organizational structure of device tree files is crucial for kernel development.

# Top-Level device tree

The top-level device tree file for Quectel Pi H1 is `qcs6490-idp-pi.dts`, which can be found in the following two locations:

- **Recommended modification location** (outside kernel code, convenient for overlay):

```plaintext
src/qcom-6.6-overlay/arch/arm64/boot/dts/qcom/qcs6490-idp-pi.dts
```

- **Location within kernel source**:

```plaintext
sources/quectel-src/kernel/qcom-6.6/arch/arm64/boot/dts/qcom/qcs6490-idp-pi.dts
```

> **Recommendation**: For all device tree modifications, it is recommended to work on files in the `src/qcom-6.6-overlay` directory.

# Common device tree files

## sc7280.dtsi

During development, the `sc7280.dtsi` file will be frequently viewed and used. This file contains the following common nodes:

- GPIO (General purpose input/output)

- SPI (Serial peripheral interface)

- I2C (I²C bus)

- UART (Serial port)

- CPU (Processor)

- GPU (Graphics processor)

**File path**:

```plaintext
sources/quectel-src/kernel/qcom-6.6/arch/arm64/boot/dts/qcom/sc7280.dtsi
```

# External device tree repositories

The Qualcomm platform separates drivers and device trees related to display, graphics, camera, video, etc. from the Linux kernel source code, forming independent code repositories.

## View repository information

You can download the Yocto project source code according to [Image build](<../Image build/Image build.md>), and obtain specific code repository information by viewing `.bb` files in the `layers/meta-qcom-hwe` directory.

**Example: View camera device tree repository**

Open the `layers/meta-qcom-hwe/recipes-multimedia/cameradtb/cameradtb_1.0.bb` file, you can see:

```bash
SRCPROJECT = "git://git.codelinaro.org/clo/le/platform/vendor/opensource/camera-devicetree.git;protocol=https"
SRCBRANCH  = "camera-kernel.qclinux.1.0.r1-rel"
SRCREV     = "08511ff747916576232cc26394bb9c5c6e0ab1f5"
```

**Information description**:

- **Repository address**: [https://git.codelinaro.org/clo/le/platform/vendor/opensource/camera-devicetree.git](<https://git.codelinaro.org/clo/le/platform/vendor/opensource/camera-devicetree.git>)

- **Branch**: camera-kernel.qclinux.1.0.r1-rel

- **Commit version**: 08511ff747916576232cc26394bb9c5c6e0ab1f5

## Local device tree sub-repository locations

To facilitate compilation and use, Quectel Pi H1 places these independent device tree sub-repositories in the `src/devicetree` directory:

| **Module** | **Path** |
| --- | --- |
| Camera | src/devicetree/camera-devicetree |
| Display | src/devicetree/display-devicetree |
| Graphics | src/devicetree/graphics-devicetree |
| Video | src/devicetree/video-devicetree |

# Detailed description of device tree for each module

## Camera

### Device tree files

- **Camera main configuration**:

```plaintext
src/devicetree/camera-devicetree/qcm6490-camera-rb3.dtsi
```

- **Camera sensor configuration**:

```plaintext
src/devicetree/camera-devicetree/qcm6490-camera-sensor-rb3.dtsi
```

### Related recipe files

- **Base recipe**:

```plaintext
layers/meta-qcom-hwe/recipes-multimedia/cameradtb/cameradtb_1.0.bb
```

- **Extension recipe**:

```plaintext
layers/meta-quectel/recipes-multimedia/cameradtb/cameradtb_1.0.bbappend
```

## Display

### Device tree files

- **8-inch screen configuration**:

```plaintext
src/devicetree/display-devicetree/display/dsi-panel-waveshare-8inch-video.dtsi
```

- **SDE display main configuration**:

```plaintext
src/devicetree/display-devicetree/display/qcm6490-sde-display-pi.dtsi
```

- **SDE display pin configuration**:

```plaintext
src/devicetree/display-devicetree/display/qcm6490-sde-display-pinctrl.dtsi
```

- **SDE display general configuration**:

```plaintext
src/devicetree/display-devicetree/display/qcm6490-sde-display.dtsi
```

- **Top-Level device tree reference**:

```plaintext
src/qcom-6.6-overlay/arch/arm64/boot/dts/qcom/qcs6490-idp-pi.dts
```

### Related recipe files

- **Base recipe**:

```plaintext
layers/meta-qcom-hwe/recipes-multimedia/display/qcom-displaydevicetree_git.bb
```

- **Extension recipe**:

```plaintext
layers/meta-quectel/recipes-multimedia/display/qcom-displaydevicetree_git.bbappend
```

## Graphics

### Device tree files

- **GPU configuration**:

```plaintext
src/devicetree/graphics-devicetree/gpu/qcm6490-graphics.dtsi
```

### Related recipe files

- **Base recipe**:

```plaintext
layers/meta-qcom-hwe/recipes-graphics/graphicsdevicetree/qcom-graphicsdevicetree_git.bb
```

- **Extension recipe**:

```plaintext
layers/meta-quectel/recipes-graphics/graphicsdevicetree/qcom-graphicsdevicetree_git.bbappend
```

## Video

### Device tree files

- **Video configuration**:

```plaintext
src/devicetree/video-devicetree/qcm6490-video.dtsi
```

### Related recipe files

- **Base recipe**:

```plaintext
layers/meta-qcom-hwe/recipes-multimedia/video/qcom-videodtb_1.0.bb
```

- **Extension recipe**:

```plaintext
layers/meta-quectel/recipes-multimedia/video/qcom-videodtb_1.0.bbappend
```

# Modification recommendations

1. **Prioritize overlay modifications**: When modifying device trees, prioritize working on files in the `src/qcom-6.6-overlay` and `src/devicetree` directories, avoiding direct modifications to kernel source code.

2. **Understand dependencies**: Before modifying device trees, it is recommended to understand the reference relationships between various `.dtsi` files.

3. **Synchronize recipe files**: If you modify device tree repositories or add new device tree files, you need to synchronously update the corresponding `.bb` and `.bbappend` files.

4. **Version control**: It is recommended to use Git to manage all modifications for easy tracking and rollback.