Need support to Set the primary Display on IMX8QM

[PunitTeksun]

Hello Support Portal,

SOC: IMX8QM

We have connected the Dual Channel display on the LDB2 node and the Single Channel display on the LDB1 node. 

Dual Channel Display: 1920X720

Single Channel Display: 1280X800

The android is detecting both the display 

Currently Android considers Single channel 1280X800 Display as a primary display and a Dual channel  1920X720 display as a secondary display. 

What we want : 

Dual channel display - primary 

Single channel display - secondary 

We have tried following things

1) First we connect the Dual channel display and then after some time we connect the single-channel display but still, the single-channel display is considered as a primary display

Note: If we disable the single-channel display node from the device tree then the dual-channel display is considered the primary display. 

[Zhiming_Liu]

This order is decided by the LDB driver probe order. The LDB1 connector should be first and then LDB2 connector.

You can find the display hal code in nxp-opensource/imx/display/display/DisplayManager.cpp

The code will set the first connector as primary device(using setPrimaryDisplay), you can judge the value of  *id to decide which device should be primary.

for (int i = 0; i < res->count_connectors; i++) {
        display = mKmsDisplays[*id];

        if (display->setDrm(drmFd, res->connectors[i]) != 0) {
            continue;
        }

        display->setDisplayLimitation(tileHwLimit);
        display->readType();
        display->readConnection();
        // primary display allow not connected.
        if (!display->connected() && (*foundPrimary || !main)) {
            (*id)++;
            continue;
        }

        if (display->openKms() != 0) {
            display->closeKms();
            (*id)++;
            continue;
        }

        // primary display is fixed by name.
        if (!*foundPrimary && main) {
            ALOGI("%s set %d as primary display", __func__, (*id));
            *foundPrimary = true;
            setPrimaryDisplay(*id);
        }