# LCD

## Kernel Device Tree

* **Top-Level Device Tree Directory**

**Android SDK Path**:

```bash
longan/device/config/chips/a133/configs/c3/kickpi-k5c.dts

#include "lcd-lvds-7-1024-600.dtsi"
//#include "lcd-lvds-21-1920-1080.dtsi"
//#include "lcd-mipi-10-800-1280-v1.dtsi"
//#include "lcd-mipi-10-800-1280-v2.dtsi"
//#include "lcd-mipi-8-800-1280.dtsi"
//#include "lcd-mipi-5-720-1280.dtsi"
```

**Linux SDK Path**:

```bash
device/config/chips/a133/configs/c3/kickpi-k5c.dts
```

* **Secondary Device Tree Directory**

**Android/Linux SDK Path**:

```bash
longan/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/
```

| Device Tree Files              | Description               |
| ------------------------------ | ------------------------- |
| `lcd-lvds-21-1920-1080.dtsi`   | 21-27" LVDS (1920x1080)   |
| `lcd-lvds-7-1024-600.dtsi`     | 7" LVDS (1024x600)        |
| `lcd-mipi-10-800-1280-v1.dtsi` | 10.1" MIPI (800x1280, v1) |
| `lcd-mipi-10-800-1280-v2.dtsi` | 10.1" MIPI (800x1280, v2) |
| `lcd-mipi-5-720-1280.dtsi`     | 5" MIPI (720x1280)        |
| `lcd-mipi-8-800-1280.dtsi`     | 8" MIPI (800x1280)        |

***

### Screen Selection and Compilation

**MIPI Screens**

| **Model**   | **Size**  | **Resolution** | **Device Tree File**           |
| ----------- | --------- | -------------- | ------------------------------ |
| AT101DS40I  | 10.1-inch | 800x1280       | `lcd-mipi-10-800-1280-v1.dtsi` |
| MX101BA1340 | 10.1-inch | 800x1280       | `lcd-mipi-10-800-1280-v2.dtsi` |
| MX080B2140  | 8.0-inch  | 800x1280       | `lcd-mipi-8-800-1280.dtsi`     |
| F050008M01  | 5.0-inch  | 720x1280       | `lcd-mipi-5-720-1280.dtsi`     |

**LVDS Screens**

| **Model** | **Size**   | **Resolution** | **Device Tree File**         |
| --------- | ---------- | -------------- | ---------------------------- |
| MX070IBC  | 7.0-inch   | 1024x600       | `lcd-lvds-7-1024-600.dtsi`   |
| -         | 21-27 inch | 1920x1080      | `lcd-lvds-21-1920-1080.dtsi` |

**Example**: Selecting the 7" LVDS screen:

```shell
$ vim longan/device/config/chips/a133/configs/c3/kickpi-k5c.dts
#include "lcd-lvds-7-1024-600.dtsi"  // Enable 7" LVDS
//#include "lcd-lvds-21-1920-1080.dtsi"  // Disable others
//#include "lcd-mipi-10-800-1280.dtsi"
```

> **Note**: Only **one** `lcd-*.dtsi` file can be enabled at a time.

***

## LCD Driver

* **UBOOT Driver Path**:

```bash
longan/brandy/brandy-2.0/u-boot-2018/drivers/video/sunxi/disp2/disp/lcd/
    mipi_800x1280.c       // MIPI LCD driver
```

* **Kernel Driver Path**:

```bash
longan/kernel/linux-4.9/drivers/video/fbdev/sunxi/disp2/disp/lcd/
    mipi_800x1280.c       // MIPI LCD driver
```

***

### Single LVDS Interface

* **Hardware Label**: `LVDS_LCD` (30-pin clamp connector).
* **Default Configuration**: Supports 7" LVDS screen (1024x600).

***

### Dual LVDS Interface

* **Hardware Label**: `DUAL_LVDS` (30-pin vertical connector).
* **Voltage Options**: 3.3V, 5V, 12V. **Select voltage based on screen specifications to avoid damage!**

**K5 Board**:\
![image-20250312140810001](http://tanzhtanzh.oss-cn-shenzhen.aliyuncs.com/img/image-20250312140810001.png)

**K5C Board**:\
![image-20250508150845033](http://tanzhtanzh.oss-cn-shenzhen.aliyuncs.com/img/image-20250508150845033.png)

> **Warnings**:
>
> 1. Ensure the power adapter provides sufficient current for the screen. Insufficient current may cause backlight flickering.
> 2. If flickering occurs, **disconnect power immediately** and replace the adapter.

***

## Debugging Information

**View Current Display Properties**:

```shell
cat /sys/class/disp/disp/attr/sys 
```

**Example Output**:

```shell
# cat /sys/class/disp/disp/attr/sys 
screen 0:
de_rate 300000000 hz, ref_fps:66
mgr0: 720x1280 fmt[rgb] cs[0x204] range[full] eotf[0x4] bits[8bits] err[1] force_sync[0] unblank direct_show[false] iommu[1]
dmabuf: cache[7] cache max[37] umap skip[0] overflow[4]
        lcd output      backlight(102)  fps:66.5         720x1280
        err:2   skip:99 irq:17699       vsync:12094     vsync_skip:0
   BUF    enable ch[3] lyr[0] z[0] prem[Y] a[globl 255] fmt[  1] fb[ 736,1280; 368, 640; 368, 640] crop[   0,   0, 720,1280] frame[   0,   0, 720,1280] addr[fec00000,fecf0000,fed29800] flags[0x       0] trd[0,0]
depth[ 0] disp[0]all:685, sub:685, cur:685, free:682, skip:0
```