How to config Multi-Display for rk3288 series Debian9

RSB-4680 surport 3 display ports : eDP、LVDS、HDMI . Only two ports work at the same time .

You can config Multi-Display to eDP + HDMI 、eDP + LVDS、LVDS + HDMI .

Enter U-boot interrupt mode

Connect device to debug port, and open debug console.

Press "ctrl + c" key before power up the device, until get the following information on debug console :

Hit any key to stop autoboot: 0
=> <INTERRUPT>
=>

Then you can input the following cammand to config Multi-Display.

setenv prmry_screen edp-1920x1080
setenv extend_screen hdmi-default
saveenv
reset

setenv prmry_screen edp-1920x1080
setenv extend_screen lvds-g070vw01
saveenv
reset

setenv prmry_screen hdmi-default
setenv extend_screen lvds-g070vw01
saveenv
reset

Port	RSB4680	USM110
edp	edp-1920x1200 edp-1920x1080 edp-1024x768	edp-1920x1080 edp-1280x720 edp-1024x768 edp-720x480 edp-640x480
lvds	lvds-g070vw01 lvds-idk1110wp lvds-g150xgel05 lvds-g215hvn01 lvds-p460hvn02	NA
hdmi	hdmi-default	hdmi-default

NOTE :

1. The name of the panel must begin with "edp-"、"lvds-" or "hdmi-" .

And it can be found in "kernel/include/dt-bindings/display/screen-timing/{LCDNAME}.dtsi" like :

lvds_g070vw01: lvds-g070vw01

2. If there is no configuration, you will get default setting :

edp-default (edp-1920x1080) and hdmi-default as default setting.

3. Check your configuration in Terminal or debug console.

cat /proc/cmdline
... prmry_screen=edp-1920x1080 extend_screen=hdmi-default