AMD APU + AMD GPU won't boot into GUI with amdgpu

[paupav]

Hello,
I have problem booting into GUI/lightdm when I enable amdgpu with

amdgpu.si_support=1 radeon.si_support=0

and

amdgpu.cik_support=1 radeon.cik_support=0

. I can boot into tty without problems and lspci -v then shows that I'm indeed using amdgpu.

Interesting part of lspci:

00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mullins [Radeon R3 Graphics] (prog-if 00 [VGA controller])
Subsystem: Lenovo Mullins [Radeon R3 Graphics]
Flags: bus master, fast devsel, latency 0, IRQ 39
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at f0000000 (64-bit, prefetchable) [size=8M]
I/O ports at 5000 [size=256]
Memory at f0d00000 (32-bit, non-prefetchable) [size=256K]
Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: [48] Vendor Specific Information: Len=08 <?>
Capabilities: [50] Power Management version 3
Capabilities: [58] Express Root Complex Integrated Endpoint, MSI 00
Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [270] #19
Capabilities: [2b0] Address Translation Service (ATS)
Capabilities: [2c0] Page Request Interface (PRI)
Capabilities: [2d0] Process Address Space ID (PASID)
Kernel driver in use: radeon
Kernel modules: radeon, amdgpu

01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Sun XT [Radeon HD 8670A/8670M/8690M / R5 M330 / M430] (rev ff) (prog-if ff)
!!! Unknown header type 7f
Kernel driver in use: radeon
Kernel modules: radeon, amdgpu01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Sun XT [Radeon HD 8670A/8670M/8690M / R5 M330 / M430] (rev ff) (prog-if ff)
!!! Unknown header type 7f
Kernel driver in use: radeon
Kernel modules: radeon, amdgpu

I'm running Ubuntu 18.04 with 4.15.0-13-generic #14-Ubuntu SMP.
I don't even know what could go wrong?

[bridgman]

When you say "interesting part of lspci" is that without the boot parms ? Guessing it is because you are using radeon, just checking.

Does it work if you enable CIK support only and leave the dGPU running on radeon ?

[paupav]

(reply to "interesting part of lspci" )I have rebooted and forgot to save output. I guess only those 2 lines are boring.

(reply to "only CIK support" ) NoNo, it doesn't. I have tried all 4 combinations.