How to Config Multi-Display for RK3399 RSB4710

RSB-4710 surport 4 display ports : eDP、LVDS（mipi to LVDS）、HDMI、DP （DP to HDMI）. Only two ports work at the same time .

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

NOTE：

        Android distinguish the primary and the extend screen. 

Contents

 [hide] 

• 1 Enter U-boot interrupt mode
• 2 eDP + HDMI
• 3 eDP + LVDS
• 4 LVDS + HDMI
• 5 eDP + DP
• 6 LVDS + DP
• 7 HDMI + DP
• 8 Default Support Display

Enter U-boot interrupt mode

Connect device to debug port, and open debug console. See more : How_to_debug.

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.

eDP + HDMI

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

or

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

eDP + LVDS

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

or

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

LVDS + HDMI

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

or

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

eDP + DP

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

or

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

LVDS + DP

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

or

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

HDMI + DP

setenv prmry_screen hdmi-default
setenv extend_screen dp-default
saveenv
reset

or

setenv prmry_screen dp-fefault
​setenv extend_screen hdmi-default
saveenv
reset

Default Support Display

Port	RSB4710
edp	edp-1920x1080 edp-1366x768
lvds	lvds-g070vw01 lvds-g150xgel05 lvds-g215hvn01
hdmi	hdmi-default
dp	dp-default

NOTE : 

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

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 :

hdmi-default  and dp-default as default setting.

3. Check your configuration in Terminal or debug console.

cat /proc/cmdline
... prmry_screen=hdmi-default extend_screen=dp-default

LVDS Name	Resolution
lvds-g070vw01	800x480
lvds-g150xgel05	1024x768
lvds-g215hvn01	1920x1080

Using envtools in Debian/Android

Using envtools to setup envs in Debian/Android OS is very similar in uboot.

Take “eDP+HDMI”for example :

In uboot	In Debian/Android
setenv prmry_screen hdmi-default	fw_setenv prmry_screen hdmi-default
setenv extend_screen edp-1920x1080	fw_setenv extend_screen edp-1920x1080
saveenv
reset	reboot

Note :

The tool "fw_setenv" will save envs automatically in Debian/Android OS, so it isn't necessary to saveen manually.