LCD

Kernel Device Tree

• Top-Level Device Tree Directory

Android SDK Path:

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:

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

• Secondary Device Tree Directory

Android/Linux SDK Path:

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)

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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:

$ 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.

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LCD Driver

• UBOOT Driver Path:

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

• Kernel Driver Path:

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

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Single LVDS Interface

• Hardware Label: LVDS_LCD (30-pin clamp connector).

• Default Configuration: Supports 7" LVDS screen (1024x600).

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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:

K5C Board:

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.

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Debugging Information

View Current Display Properties:

cat /sys/class/disp/disp/attr/sys 

Example Output:

# 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