Kernels >= 6.3 disable video output

Fri May 9 00:07:54 UTC 2025

 AMD 2400g, Zen1, 'Raven' firmware, igpu, no card.
Code that was added to 6.2.16 to create 6.3 and up, to last tested 
6.13.4, breaks the igpu for Ryzen. Kernels with firmware, same as that 
used on 6.3 and up, works 100% on 5.4 to 6.2.16. This bug is even in a 
Debian/Ubuntu based OS's Mainline download of 6.8 (only mainline 
tested). Without using firmware, allowing fbdev drivers to control 
output to monitor, 6.13.4 works.
 The bug is that about 70% of the time, with firmware, the output to 
the monitor is shut off. The monitor displays no input connection. With 
no monitor the Linux console works the same as monitor connected. Both 
blanked and displayed have:
 > [ 0.000000] Linux version 6.13.4 (root at steven-ryzen) (gcc (GCC) 
14.2.0, GNU ld (GNU Binutils) 2.44) #1 SMP PREEMPT_DYNAMIC Thu May 8 
13:55:46 EDT 2025
 > [ 0.310823] ACPI: bus type drm_connector registered
 > [ 0.310837] [drm] amdgpu kernel modesetting enabled.
 > [ 0.310975] [drm] initializing kernel modesetting (RAVEN 
0x1002:0x15DD 0x1002:0x15DD 0xC6).
 > [ 0.310989] [drm] register mmio base: 0xFC900000
 > [ 0.310994] [drm] register mmio size: 524288
 > [ 0.311024] [drm] add ip block number 0 <soc15_common>
 > [ 0.311029] [drm] add ip block number 1 <gmc_v9_0>
 > [ 0.311034] [drm] add ip block number 2 <vega10_ih>
 > [ 0.311039] [drm] add ip block number 3 <psp>
 > [ 0.311043] [drm] add ip block number 4 <powerplay>
 > [ 0.311047] [drm] add ip block number 5 <dm>
 > [ 0.311052] [drm] add ip block number 6 <gfx_v9_0>
 > [ 0.311057] [drm] add ip block number 7 <sdma_v4_0>
 > [ 0.311061] [drm] add ip block number 8 <vcn_v1_0>
 > [ 0.334228] [drm] BIOS signature incorrect 0 0
 > [ 0.334251] amdgpu 0000:0e:00.0: amdgpu: Fetched VBIOS from ROM BAR
 > [ 0.334258] amdgpu: ATOM BIOS: 113-RAVEN-113
 > [ 0.334554] amdgpu 0000:0e:00.0: vgaarb: deactivate vga console
 > [ 0.334560] amdgpu 0000:0e:00.0: amdgpu: Trusted Memory Zone (TMZ) 
feature enabled
 > [ 0.334585] [drm] vm size is 262144 GB, 4 levels, block size is 
9-bit, fragment size is 9-bit
 > [ 0.334596] amdgpu 0000:0e:00.0: amdgpu: VRAM: 2048M 
0x000000F400000000 - 0x000000F47FFFFFFF (2048M used)
 > [ 0.334604] amdgpu 0000:0e:00.0: amdgpu: GART: 1024M 
0x0000000000000000 - 0x000000003FFFFFFF
 > [ 0.334615] [drm] Detected VRAM RAM=2048M, BAR=2048M
 > [ 0.334619] [drm] RAM width 128bits DDR4
 > [ 0.334722] [drm] amdgpu: 2048M of VRAM memory ready
 > [ 0.334727] [drm] amdgpu: 2923M of GTT memory ready.
 > [ 0.334742] [drm] GART: num cpu pages 262144, num gpu pages 262144
 > [ 0.334877] [drm] PCIE GART of 1024M enabled.
 > [ 0.334881] [drm] PTB located at 0x000000F400A00000
 > [ 0.335145] amdgpu: hwmgr_sw_init smu backed is smu10_smu
 > [ 0.335578] [drm] Found VCN firmware Version ENC: 1.15 DEC: 3 VEP: 0 
Revision: 0
 > [ 0.356133] amdgpu 0000:0e:00.0: amdgpu: reserve 0x400000 from 
0xf47fc00000 for PSP TMR
 > [ 0.428083] amdgpu 0000:0e:00.0: amdgpu: RAS: optional ras ta ucode 
is not available
 > [ 0.434083] amdgpu 0000:0e:00.0: amdgpu: RAP: optional rap ta ucode 
is not available
 > [ 0.434090] amdgpu 0000:0e:00.0: amdgpu: SECUREDISPLAY: 
securedisplay ta ucode is not available
 > [ 0.434559] [drm] DM_PPLIB: values for F clock
 > [ 0.434564] [drm] DM_PPLIB: 1633000 in kHz, 4399 in mV
 > [ 0.434570] [drm] DM_PPLIB: values for DCF clock
 > [ 0.434574] [drm] DM_PPLIB: 300000 in kHz, 3649 in mV
 > [ 0.434578] [drm] DM_PPLIB: 600000 in kHz, 4074 in mV
 > [ 0.434583] [drm] DM_PPLIB: 626000 in kHz, 4250 in mV
 > [ 0.434587] [drm] DM_PPLIB: 654000 in kHz, 4399 in mV
 > [ 0.435247] [drm] Display Core v3.2.310 initialized on DCN 1.0
 > [ 0.504716] [drm] kiq ring mec 2 pipe 1 q 0
 > [ 0.518487] amdgpu 0000:0e:00.0: amdgpu: SE 1, SH per SE 1, CU per 
SH 11, active_cu_number 11
 > [ 0.518497] amdgpu 0000:0e:00.0: amdgpu: ring gfx uses VM inv eng 0 
on hub 0
 > [ 0.518503] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.0.0 uses VM inv 
eng 1 on hub 0
 > [ 0.518510] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.1.0 uses VM inv 
eng 4 on hub 0
 > [ 0.518516] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.2.0 uses VM inv 
eng 5 on hub 0
 > [ 0.518523] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.3.0 uses VM inv 
eng 6 on hub 0
 > [ 0.518530] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.0.1 uses VM inv 
eng 7 on hub 0
 > [ 0.518536] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.1.1 uses VM inv 
eng 8 on hub 0
 > [ 0.518543] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.2.1 uses VM inv 
eng 9 on hub 0
 > [ 0.518549] amdgpu 0000:0e:00.0: amdgpu: ring comp_1.3.1 uses VM inv 
eng 10 on hub 0
 > [ 0.518556] amdgpu 0000:0e:00.0: amdgpu: ring kiq_0.2.1.0 uses VM 
inv eng 11 on hub 0
 > [ 0.518562] amdgpu 0000:0e:00.0: amdgpu: ring sdma0 uses VM inv eng 
0 on hub 8
 > [ 0.518569] amdgpu 0000:0e:00.0: amdgpu: ring vcn_dec uses VM inv 
eng 1 on hub 8
 > [ 0.518575] amdgpu 0000:0e:00.0: amdgpu: ring vcn_enc0 uses VM inv 
eng 4 on hub 8
 > [ 0.518581] amdgpu 0000:0e:00.0: amdgpu: ring vcn_enc1 uses VM inv 
eng 5 on hub 8
 > [ 0.518588] amdgpu 0000:0e:00.0: amdgpu: ring jpeg_dec uses VM inv 
eng 6 on hub 8
 > [ 0.521453] amdgpu: pp_dpm_get_sclk_od was not implemented.
 > [ 0.521460] amdgpu: pp_dpm_get_mclk_od was not implemented.
 > [ 0.521565] amdgpu 0000:0e:00.0: amdgpu: Runtime PM not available
 > [ 0.521868] [drm] Initialized amdgpu 3.60.0 for 0000:0e:00.0 on 
minor 0
 > [ 0.526617] fbcon: amdgpudrmfb (fb0) is primary device
 > [ 0.595813] Console: switching to colour frame buffer device 240x67
 > [ 0.628478] amdgpu 0000:0e:00.0: [drm] fb0: amdgpudrmfb frame buffer 
device

 I have no idea which code to regress to get back to 6.2.16 to make 
work again. From a quick look, that is the kernels where code was 
adopting new naming conventions for drivers, among tons of other 
changes. Think was also the start of PState default of 3, which setting 
to 1 made no difference, maybe lessened blackout closer to 50%?
Please help, I luv my 2400g! 6.1.137 is great and 5.15 is fine too. I 
still use 5.4 for testing my code too.
Steve
PS. please cc me, I'm not on the list referred by fb-dev.