Display Vertically shifted IMX8mq-evk board in dual display use case(HDMI 2)

[sandeep_yenugul]

Hi all,

We are evaluating the dual display use case in NXP's imx8mq based evk board with your
L4.14.98-GA prebuild image. For dual display use case, we referred Quick Start Guide for IMX-MIPI-HDMI for i.MX 8M Evaluation Kit. We stopped booting process at uboot and setenv fdt_file fsl-imx8mq-evk-dual-display-b3.dtb for dual display then boot the kernel.

We see both displays working fine. but after some time when we hard reboot the system screen on MIPI-DS, I (HDMI2)bridge is shifted on vertically.

I have attached photos for your reference.

We are developing imx8mq based on our custom design and dual display use case is part of our project. So,

Can you please help us to resolve this issue ASAP?

Please let me know if you need further information.

Thanks,
Sandeep

[igorpadykov]

Hi Sandeep

one can try:

1. check lcd power-up sequence, as lcd may require that power-up sequence was

implemented, then it may require delay and only then receive data.

2. check with several lcds.

Also according to i.MX8MQ power-up sequence requirements (described in sect.

3.2.3 Power supplies usage Datasheet), during i.MX8MQ power-up sequence there should

not be externally applied voltages to processor. So one can try to disconnect LCDs,

reboot processor and check if issue persist.

Best regards
igor
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[sandeep_yenugul]

Hi Igor,

Thanks for the suggestion.

We are not using any external LCD for the connection.

We have seen this observation with LG, Dell and Samsung HDMI display.

In our Scenario, We have used TWO HDMI display for two HDMI connection on EVK. One HDMI display is connected on EVK board's HDMI connector(J1001) and Second HDMI display is connected through the IMX-MIPI-HDMI connector.

We are using the external power supply for the HDMI display.

Can you help us to resolve these issues?

Reg,

Sandeep

[igorpadykov]

Hi Sandeep

could you test scenario when both lcds (TWO HDMI displays) were also shortly powered off

during board reset.

Best regards
igor

[felixradensky]

Hi,

We also observe this behavior on LVDS display connected to MIPI-DSI via SN65DSI84 DSI to LVDS bridge. It is easily reproducible by doing suspend-resume sequence. We don't see this problem on our i.MX8M Mini board using the same display and LVDS bridge. We suspect  i.MX8M MIPI-DSI bridge driver.

Felix.