drm kmod with Vega 3

[Andriy Gapon]

I am trying to get FreeBSD going on Motile M141 notebook that has a Ryzen
processor with integrated graphics: AMD Ryzen 3 3200U with Radeon Vega Mobile Gfx.

So, far, X works only with scfb or vesa depending whether I boot in EFI or
legacy mode.  amdgpu driver from drm kmod package version 4.16.g20200320 does
not detect the hardware. The driver from drm-devel-kmod version 5.0.g20200320
detects the hardware but fails to attach and that makes the screen freeze.

The interesting part of the attach log:
[drm] PSP loading VCN firmware
[drm] reserve 0x400000 from 0xf400c00000 for PSP TMR SIZE
[drm ERROR :psp_cmd_submit_buf] failed loading with status (-53233) and ucode id
(10)
[drm ERROR :psp_hw_init] PSP firmware loading failed
[drm ERROR :amdgpu_device_fw_loading] hw_init of IP block <psp> failed -22
drmn0: amdgpu_device_ip_init failed
drmn0: Fatal error during GPU init

Does anyone have any suggestions or ideas?
Thank you!

P.S.
I found this bug report
https://bugs.freedesktop.org/show_bug.cgi?id=109206
but my error code is different and a workaround from the bug report does not help.

P.P.S.
Just in case anyone is interested, here are more details about the notebook:
https://wiki.freebsd.org/Laptops/Motile_M141
-- 
Andriy Gapon