U-boot internal screen support for A311D - issue 21

1

I’m experimenting with replacing initramfs-tools with dracut to include systemd into initramfs so I can decrypt my NVMe with FIDO2 key. I got some success with original iMX8M CPU module but following similar steps on A311D results with blank screen.

Side note - I haven’t yet published post describing entire procedure wanting to have working, reliable solution. If there is interest I might publish my steps so others can try to reproduce.

Because u-boot on A311D cannot initialize internal screen and only Linux can display something, I cannot debug anything. I’ve noticed that there is an issue related to that problem:

but there wasn’t any activity after its creation. At the same time scripts building u-boot for A311D (and other modules) were extracted to separate repository

although there are still files in old repository mention that chip:

I’ve upgraded to latest available u-boot to 2024-08-01
https://source.mnt.re/reform/reform-a311d-uboot/-/jobs/artifacts/2024-08-01/raw/meson-g12b-bananapi-cm4-mnt-reform2-flash.bin\?job\=build SHA1:9f762b7d3dc447ee6d4e5e5f28f7cc682a6c226f
but it didn’t help with this particular problem.

Is there anything someone without much hardware knowledge do? I tried reading files with reform in their names from upstream u-boot repository, but haven’t understood much. OTOH if there are some patches to try, I might compile u-boot and give it a try.

There was similar discussion for original iMX8M CPU in 2021:
https://community.mnt.re/t/u-boot-and-internal-screen/

2 Likes
2

You need a second machine and a USB UART serial adapter.

Yes, the issue serves to document the status quo. There being an issue does not mean that a solution magically manifests.

What does that have to do with this?

That is an oversight. I have moved the README from reform-system-image to reform-a311d-uboot now.

Yes, there is no display support in a311d u-boot as recorded in the issue you found.

Yes, somebody with much hardware knowledge and either a lot of freetime or an employer interested in this feature could add display support to u-boot for the BPI CM4 A311D.

To my knowledge, there are none.

1 Like
3

Yes, somebody with much hardware knowledge and either a lot of freetime or an employer interested in this feature could add display support to u-boot for the BPI CM4 A311D.

I had a brief look on how the display support in the Boundary Device (so, for imx8mp) uboot works, and … bleh. It has it’s own invention of a low-level MIPI DSI driver, which needs panel-specific setup codes, which idk where they would come from. Having seen that I shelved further exploration for now.

1 Like
4

Panel specific init is the easiest thing (for me) here. I can fix that up if someone else brings up DSI in general on these platforms in u-boot.

2 Likes