Created attachment 145821 [details]
dmesg (kernel 5.4-rc4)

My card (Radeon R9 290 Tri-X) tells me 3 times it fails to get get encoder_cap_info from VBIOS with error code 4.

[...]
[    6.084919] [drm] amdgpu kernel modesetting enabled.
[    6.086395] CRAT table not found
[    6.086493] Virtual CRAT table created for CPU
[    6.086560] Parsing CRAT table with 2 nodes
[    6.086755] Creating topology SYSFS entries
[    6.088841] Topology: Add CPU node
[    6.088952] Finished initializing topology
[    6.090354] amdgpu 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 0: 0xd0000000 -> 0xdfffffff
[    6.090480] amdgpu 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 2: 0xcf800000 -> 0xcfffffff
[    6.090601] amdgpu 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 5: 0xfe980000 -> 0xfe9bffff
[    6.102438] [drm] initializing kernel modesetting (HAWAII 0x1002:0x67B0 0x174B:0xE285 0x00).
[    6.102810] [drm] register mmio base: 0xFE980000
[    6.102906] [drm] register mmio size: 262144
[    6.103008] [drm] PCIE atomic ops is not supported
[    6.103115] [drm] add ip block number 0 <cik_common>
[    6.103211] [drm] add ip block number 1 <gmc_v7_0>
[    6.103312] [drm] add ip block number 2 <cik_ih>
[    6.103402] [drm] add ip block number 3 <gfx_v7_0>
[    6.103497] [drm] add ip block number 4 <cik_sdma>
[    6.103604] [drm] add ip block number 5 <powerplay>
[    6.103705] [drm] add ip block number 6 <dm>
[    6.103812] [drm] add ip block number 7 <uvd_v4_2>
[    6.103912] [drm] add ip block number 8 <vce_v2_0>
[    6.104297] resource sanity check: requesting [mem 0x000c0000-0x000dffff], which spans more than PCI Bus 0000:00 [mem 0x000d0000-0x000dffff window]
[    6.104497] caller pci_map_rom+0x65/0x180 mapping multiple BARs
[    6.106500] ATOM BIOS: 113-C6710100-O05
[    6.108480] [drm] vm size is 128 GB, 2 levels, block size is 10-bit, fragment size is 9-bit
[    6.114123] e1000e 0000:02:00.0 enp2s0: renamed from eth0
[    6.121192] usb usb3: New USB device found, idVendor=1d6b, idProduct=0001, bcdDevice= 5.04
[    6.121329] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    6.121454] usb usb3: Product: OHCI PCI host controller
[    6.121559] usb usb3: Manufacturer: Linux 5.4.0-rc4 ohci_hcd
[    6.121667] usb usb3: SerialNumber: 0000:00:12.0
[    6.125828] hub 3-0:1.0: USB hub found
[    6.126006] hub 3-0:1.0: 3 ports detected
[    6.136409] ohci-pci 0000:00:12.1: OHCI PCI host controller
[    6.136686] ohci-pci 0000:00:12.1: new USB bus registered, assigned bus number 4
[    6.137314] ohci-pci 0000:00:12.1: irq 16, io mem 0xfe8fe000
[    6.139369] amdgpu 0000:01:00.0: VRAM: 4096M 0x000000F400000000 - 0x000000F4FFFFFFFF (4096M used)
[    6.139505] amdgpu 0000:01:00.0: GART: 1024M 0x000000FF00000000 - 0x000000FF3FFFFFFF
[    6.139651] [drm] Detected VRAM RAM=4096M, BAR=256M
[    6.139747] [drm] RAM width 512bits GDDR5
[    6.143904] [TTM] Zone  kernel: Available graphics memory: 16436068 KiB
[    6.144093] [TTM] Zone   dma32: Available graphics memory: 2097152 KiB
[    6.144194] [TTM] Initializing pool allocator
[    6.144667] [TTM] Initializing DMA pool allocator
[    6.146087] [drm] amdgpu: 4096M of VRAM memory ready
[    6.146348] [drm] amdgpu: 4096M of GTT memory ready.
[    6.147358] [drm] GART: num cpu pages 262144, num gpu pages 262144
[    6.148692] [drm] PCIE GART of 1024M enabled (table at 0x000000F400900000).
[    6.181882] amdgpu: [powerplay] hwmgr_sw_init smu backed is ci_smu
[    6.187238] [drm] Found UVD firmware Version: 1.64 Family ID: 9
[    6.190278] [drm] Found VCE firmware Version: 50.10 Binary ID: 2
[    6.201941] usb usb4: New USB device found, idVendor=1d6b, idProduct=0001, bcdDevice= 5.04
[    6.202059] usb usb4: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    6.202165] usb usb4: Product: OHCI PCI host controller
[    6.202318] usb usb4: Manufacturer: Linux 5.4.0-rc4 ohci_hcd
[    6.202411] usb usb4: SerialNumber: 0000:00:12.1
[    6.204076] [drm] PCIE gen 2 link speeds already enabled
[    6.205321] hub 4-0:1.0: USB hub found
[    6.205841] hub 4-0:1.0: 3 ports detected
[    6.294583] ohci-pci 0000:00:13.0: OHCI PCI host controller
[    6.294691] ohci-pci 0000:00:13.0: new USB bus registered, assigned bus number 5
[    6.295006] ohci-pci 0000:00:13.0: irq 18, io mem 0xfe8f7000
[    6.316082] [drm] dce110_link_encoder_construct: Failed to get encoder_cap_info from VBIOS with error code 4!
[    6.316555] [drm] dce110_link_encoder_construct: Failed to get encoder_cap_info from VBIOS with error code 4!
[    6.317065] [drm] dce110_link_encoder_construct: Failed to get encoder_cap_info from VBIOS with error code 4!
[    6.317673] [drm] Display Core initialized with v3.2.48!
[...]