01
What is Multi-Screen Splicing Display?
Multi-screen splicing display refers to the combination of several monitors (such as MIPI screens, HDMI screens, or DP screens) to create a large screen. For example, conference rooms are one of the primary application scenarios for splicing screens. In conference rooms, splicing screens can be used to display meeting agendas, presentation materials, video conferences, etc. The splicing screen can combine multiple screens into one large screen, allowing participants to see the presentation content more clearly and improving meeting efficiency.
Additionally, video walls are another major application scenario for splicing screens. In video walls, splicing screens can be used to broadcast television programs, sports events, news reports, etc. The splicing screen can combine multiple screens into one large screen, allowing viewers to see the program content more clearly and enhancing the viewing experience.
02
What is the Connector-Split Function?
The Connector-split function provided by the display controller in the RK3588 processor is a technology similar to the MIPI dual-channel mode, which can split the output of a single video port into two parts horizontally, thereby simultaneously driving two display interfaces. These two interfaces maintain consistency in display timing but present independent content.
Looking at the image above, if the Connector-split mode is enabled on VP0, then the output of VP0 can simultaneously drive two display interfaces, and the content displayed on these two interfaces will be horizontally split from the output of VP0. For example, if VP0 outputs at a resolution of 3840×1080, then each display interface will show an output of 1920×1080.
Using this technology, it is possible to expand to 7 independent display outputs on the RK3588. It is important to note that for each VP participating in Connector-split output, the two display interfaces must have the same output timing and frame rate. This display feature can be toggled via dts, as long as the two display interfaces participating in Connector-split are connected to the same VP and the split-mode attribute of the left display interface is enabled.
03
Dual MIPI Screen Splicing Display
Demo effect: Using the Xun as RK3588 development board and two 7-inch MIPI screens for screen splicing display.
■ Step 1:
Modify the Linux source device tree file3588-linux/kernel-5.10/arch/arm64/boot/dts/rockchip/topeet-rk3588-v10.dts
Enable the macro definitions for MIPI0 and MIPI1 as shown below:
■ Step 2:
Modify the dsi0 node, adding the content in the red box.
As shown above, let’s explain the modified content.
● rockchip,dual-channel = <&dsi1>; indicates enabling split mode by associating dsi0 and dsi1. ● rockchip,data-swap; indicates setting the left and right screens to swap. ● dsi,lanes = <8>; indicates one MIPI screen is 4 lanes, thus two MIPI screens are 8 lanes. ● enable-gpios = <&gpio2 RK_PB6 GPIO_ACTIVE_HIGH>; here sets the reset pin for the second MIPI screen.
■ Step 3:
Next, modify the timing of the mipi0 screen, changing to the content in the red box.
As shown above, let’s explain the modifications in the image.
clock-frequency，hactive，hfront-porch，hsync-len，hback-porch these attributes need to be multiplied by 2, because two 800×1280 MIPI screens horizontally spliced together become a 1600×1280 screen, so the horizontal timing parameters of the original mipi0 screen need to be multiplied by 2.
■ Step 4:
Disable the route node, panel node, and display path for the mipi1 screen.
After modifying the file, save the changes and exit. Then recompile the Linux source to burn the Linux image.
-DEMO Display Effect-
The left screen shows the left content, while the right screen shows the right content.
-END-
