AMD 6800 and 7600 - JMT M.2 - Oculink Issues

[pebwindkraft]

Hi teams,

wondering were I go wrong... I can't get the RasPi5 see my graphics card.
My Hardware and Software Setup:

• Sapphire PULSE AMD RADEON RX 7600 OC 8GB
• Sapphire PULSE AMD RADEON RX 6800 16GB
• JMT M.2 M-Key to PCIE 4.0X4 External Graphics Card Stand
• Chenyang SFF-8611 Cable OCuLink PCIe PCI-Express 4.0 SFF-8611 4i Male to SFF-8611 Male Data Extension Cable
• ATX Themaltake TR2-530AH2NSW 530 Watt
• Raspberry Pi 5 Model B Rev 1.1
• RASPBERRY PI M.2 HAT+ and iUniker PCIe M.2 HAT+
• Linux 6.12.25-v8-16k-AMD … aarch64 GNU/Linux

JMT graphics card stand and Oculink cable ordered via Jeff’s web page links. Code was downloaded [via git from Coreforge](git clone --depth=1 --branch rpi-6.6.y-gpu https://github.com/Coreforge/linux.git). Also tried 6.12.y-gpu branch.
I compiled along the lines from Jeff’s webpage. I tried first with the RX7600 8GB card, as this card appears in Jeff's list. Also wanted to get my RX6800 16GB to work, I meant I have seen someone reporting it working… Anyhow: after rebooting the RasPi5, I can see my kernel build with the “AMD” extension got bootet. Good. But I never see my graphics cards.

dmesg | grep amdgpu
[    2.536408] [drm] amdgpu kernel modesetting enabled.
lspci
0002:00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2712 PCIe Bridge (rev 30)
0002:01:00.0 Ethernet controller: Raspberry Pi Ltd RP1 PCIe 2.0 South Bridge

One remark: when I use the JMT stand as is, no lights were turning on. The ATX reamined silent. It is connected only with the large 24 pin connector to the board, the 6+2 connector goes directly into the graphics card. On the JMT stand I found three switches, and I had to change switch 3 to position 2 (“on”). The JMT board would now show 2 green LEDs (3 and 12 Volt), CL would be dark, and “RE” is red.

I put it away for a week, now just to thoroughly test again. I went to fetch the linux-rpi-6.18.y-pcie-gpu kernel as well, and followed the same process. Same result. No additional PCI bridge detected. Shouldn’t I see on an empty JMT slot at least another device? Any hint, how I could proceed?
Order a second JMT and cable would be possible, but seems not yet obvious to me, I’d hope my learning curve is too steep ;-)

[geerlingguy]

@pebwindkraft Note that the easiest way to get going is no longer Coreforge's branch (it's pretty far behind the main kernel now), but rather this one: raspberrypi/linux#7072

You can install it with:

sudo rpi-update pulls/7072

Otherwise, the branch to work from is geerlingguy/linux#10 with all the latest changes (it's way simpler, too).

If lspci doesn't see any graphics card, something physical isn't quite working.

It could be the cabling, could be the dock, or could be the GPU itself. Make sure the card is getting power and the PCIe power cable is seated well on the card. It should spin up the fans, at least, when you turn on the power supply.

I don't remember all the LED meanings on the board, but most AMD cards have at least an LED or light on them somewhere, and/or the fans spinning, to indicate it's getting power.

Then when you boot the Pi, normally (even if the driver doesn't load properly), the fan spin will change, or it will spin down the fans.

Until lspci shows something, the software/kernel side isn't as important.

Hopefully the Pi firmware is up to date? Do a fresh Pi OS install, then sudo apt upgrade everything. Check firmware version with rpi-update.