Problem with kernel splash image using two displays

Technical Support
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1

Good morning everyone,

I am working on my usual platform:

Apalis iMX8QM V1.1E

Ixora V1.2A

My initial configuration in u-boot was as follows:

skip_fdt_overlays=1

fdt_overlays=apalis-imx8_lvds_overlay.dtbo

Everything was working fine.

However, we now have a new project underway, and for some time I have been trying to work on my board with two connected displays, one HDMI and one LVDS.

To do this, I had to set the previous environment variables as follows:

skip_fdt_overlays=0

fdt_overlays=apalis-imx8_lvds_overlay.dtbo apalis-imx8_hdmi_overlay.dtbo

The two displays work, but the problem is that I no longer see the kernel splash screen image.

For me, it is essential that the kernel splash image is visible on LVDS.

How can I manage this?

2

Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

Kernel Splash Screen Limitations on i.MX8 Modules

Based on the documentation, there are important limitations regarding splash screens on i.MX8-based modules that explain your issue.

Current Status of Splash Screen Support

The Linux Kernel splash screen support has been dropped starting from BSP 6 (1). As an alternative, Toradex recommends utilizing Plymouth Splash Screen (1).

Known Issues with i.MX8 Splash Screens

For i.MX8-based modules specifically, there are several documented limitations (2):

  • Mainline U-boot doesn’t support video displays on i.MX8-based modules
  • U-boot Splash Screen is very static and requires U-boot recompilation
  • Linux Kernel Splash Screen is also very limited, static, and requires Kernel recompilation
  • There seems to be no mechanism for a smooth transition of the video handling between U-boot and the Linux Kernel

Display Configuration for Apalis iMX8

Your Apalis iMX8 provides display signals over both HDMI and LVDS (3). The module supports:

  • HDMI1 with DRM Connector Name “HDMI-A-1”
  • LVDS1 with DRM Connector Name “LVDS-1”
  • Both interfaces support EDID (software) (3)

Recommended Solution

Since the traditional kernel splash screen approach has limitations on i.MX8, you should consider implementing a Plymouth-based splash screen solution (1). This would provide better support for your dual-display configuration while maintaining the splash screen functionality you require on the LVDS display.

The discussion about splash screen solutions for i.MX8 modules is ongoing within Toradex, with documentation showing methods for enabling splash screens being developed (2).

Best regards, Toradex AI Assistant.

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3

I’m using BSP 5.7 and for the moment, since I am in prototyping phase, I would prefer to not upgrade my BPS

4

Hi @Merlin

BSP 5 is already in EOL and it’s currently not maintained anymore.

If you are just starting in development, that’s even more reason to use an up-to-date version :thinking:

As mentioned by ToradexAI, this is not supported anymore.

Maybe you want to check this other thread.

5

Hi @allan.tx

The problem is that four years in the medical field is a very short time when you consider the time required for prototyping and certification.

Obviously, when I have time, I will update the BSP, as I have done in the past: the last project I worked on was prototyped with version 3 and then updated to BSP5.

Porting my changes from one version of a BSP to another is not an easy task, it never has been, especially for someone like me who is not exactly an expert in these things. But that’s another problem and not the subject of this topic.

If ultimately the only way I can work well with psplash is to switch to a newer BSP… I’ll do that.