Re: [PATCH 2/2] drm/i915/display: Disable display for iMac's

[Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>]

>At a glance, this seems like the appropriate level.
> 
> What if you drop patch 2 and supply i915.disable_display=1 module
> parameter? Or return false from intel_display_device_enabled().

I added the i915.disable_display=1 module parameter and removed the patch
, but then the display just goes blank, here are some logs:

$ cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-6.19.0-rc4+ root=UUID=c058ecbb-6bf6-480c-943a-e8c48a831554 ro pcie_ports=native intel_iommu=on iommu=pt i915.disable_display=1

$ $ sudo cat /sys/module/i915/parameters/disable_display 
Y

$ dmesg | grep i915
[    5.255798] i915 0000:00:02.0: [drm] Found cometlake (device ID 9bc8) integrated display version 9.00 stepping N/A
[    5.256392] i915 0000:00:02.0: [drm] VT-d active for gfx access
[    5.256437] i915 0000:00:02.0: [drm] Using Transparent Hugepages
[    5.263588] i915 0000:00:02.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xffff
[    5.263592] i915 0000:00:02.0: [drm] Failed to find VBIOS tables (VBT)
[    5.263698] i915 0000:00:02.0: vgaarb: VGA decodes changed: olddecodes=io+mem,decodes=none:owns=io+mem
[    5.993265] i915 0000:00:02.0: [drm] [ENCODER:105:DDI A/PHY A] failed to retrieve link info, disabling eDP
[    5.994957] mei_hdcp 0000:00:16.0-b638ab7e-94e2-4ea2-a552-d1c54b627f04: bound 0000:00:02.0 (ops i915_hdcp_ops [i915])
[    6.308891] i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4)
[    6.310598] i915 0000:00:02.0: [drm] Registered 3 planes with drm panic
[    6.310602] [drm] Initialized i915 1.6.0 for 0000:00:02.0 on minor 1
[    6.314962] i915 0000:00:02.0: [drm] Cannot find any crtc or sizes
[    6.318910] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops intel_audio_component_bind_ops [i915])

$ dmesg | grep amdgpu
[    8.655793] [drm] amdgpu kernel modesetting enabled.
[    8.656000] amdgpu: Virtual CRAT table created for CPU
[    8.656025] amdgpu: Topology: Add CPU node
[    8.656191] amdgpu 0000:03:00.0: amdgpu: initializing kernel modesetting (NAVI14 0x1002:0x7340 0x106B:0x0219 0x47).
[    8.656203] amdgpu 0000:03:00.0: amdgpu: register mmio base: 0x81600000
[    8.656204] amdgpu 0000:03:00.0: amdgpu: register mmio size: 524288
[    8.660144] amdgpu 0000:03:00.0: amdgpu: detected ip block number 0 <common_v1_0_0> (nv_common)
[    8.660146] amdgpu 0000:03:00.0: amdgpu: detected ip block number 1 <gmc_v10_0_0> (gmc_v10_0)
[    8.660147] amdgpu 0000:03:00.0: amdgpu: detected ip block number 2 <ih_v5_0_0> (navi10_ih)
[    8.660149] amdgpu 0000:03:00.0: amdgpu: detected ip block number 3 <psp_v11_0_0> (psp)
[    8.660150] amdgpu 0000:03:00.0: amdgpu: detected ip block number 4 <smu_v11_0_0> (smu)
[    8.660151] amdgpu 0000:03:00.0: amdgpu: detected ip block number 5 <dce_v1_0_0> (dm)
[    8.660152] amdgpu 0000:03:00.0: amdgpu: detected ip block number 6 <gfx_v10_0_0> (gfx_v10_0)
[    8.660154] amdgpu 0000:03:00.0: amdgpu: detected ip block number 7 <sdma_v5_0_0> (sdma_v5_0)
[    8.660155] amdgpu 0000:03:00.0: amdgpu: detected ip block number 8 <vcn_v2_0_0> (vcn_v2_0)
[    8.660156] amdgpu 0000:03:00.0: amdgpu: detected ip block number 9 <jpeg_v2_0_0> (jpeg_v2_0)
[    8.660172] amdgpu 0000:03:00.0: amdgpu: Fetched VBIOS from VFCT
[    8.660174] amdgpu: ATOM BIOS: 113-D322A1XL-011
[    8.687707] amdgpu 0000:03:00.0: vgaarb: deactivate vga console
[    8.687710] amdgpu 0000:03:00.0: amdgpu: Trusted Memory Zone (TMZ) feature disabled as experimental (default)
[    8.687766] amdgpu 0000:03:00.0: amdgpu: vm size is 262144 GB, 4 levels, block size is 9-bit, fragment size is 9-bit
[    8.687782] amdgpu 0000:03:00.0: BAR 0 [mem 0xa0000000-0xafffffff 64bit pref]: releasing
[    8.687784] amdgpu 0000:03:00.0: BAR 2 [mem 0xb0000000-0xb01fffff 64bit pref]: releasing
[    8.687798] amdgpu 0000:03:00.0: BAR 0 [mem 0x4100000000-0x41ffffffff 64bit pref]: assigned
[    8.687805] amdgpu 0000:03:00.0: BAR 2 [mem 0x4080000000-0x40801fffff 64bit pref]: assigned
[    8.687842] amdgpu 0000:03:00.0: amdgpu: VRAM: 4080M 0x0000008000000000 - 0x00000080FEFFFFFF (4080M used)
[    8.687843] amdgpu 0000:03:00.0: amdgpu: GART: 512M 0x0000000000000000 - 0x000000001FFFFFFF
[    8.687947] amdgpu 0000:03:00.0: amdgpu: amdgpu: 4080M of VRAM memory ready
[    8.687949] amdgpu 0000:03:00.0: amdgpu: amdgpu: 7918M of GTT memory ready.
[    8.688772] amdgpu 0000:03:00.0: amdgpu: [VCN instance 0] Found VCN firmware Version ENC: 1.21 DEC: 7 VEP: 0 Revision: 2
[    8.754221] amdgpu 0000:03:00.0: amdgpu: reserve 0x900000 from 0x80fd000000 for PSP TMR
[    8.823385] amdgpu 0000:03:00.0: amdgpu: RAS: optional ras ta ucode is not available
[    8.834600] amdgpu 0000:03:00.0: amdgpu: RAP: optional rap ta ucode is not available
[    8.834603] amdgpu 0000:03:00.0: amdgpu: SECUREDISPLAY: optional securedisplay ta ucode is not available
[    8.834654] amdgpu 0000:03:00.0: amdgpu: use vbios provided pptable
[    8.834656] amdgpu 0000:03:00.0: amdgpu: smc_dpm_info table revision(format.content): 4.5
[    8.849207] amdgpu 0000:03:00.0: amdgpu: SMU is initialized successfully!
[    8.849532] amdgpu 0000:03:00.0: amdgpu: [drm] Display Core v3.2.359 initialized on DCN 2.0
[    8.849534] amdgpu 0000:03:00.0: amdgpu: [drm] DP-HDMI FRL PCON supported
[    8.881799] snd_hda_intel 0000:03:00.1: bound 0000:03:00.0 (ops amdgpu_dm_audio_component_bind_ops [amdgpu])
[    9.011896] amdgpu 0000:03:00.0: amdgpu: kiq ring mec 2 pipe 1 q 0
[    9.036429] amdgpu: HMM registered 4080MB device memory
[    9.545268] amdgpu 0000:03:00.0: amdgpu: Fence fallback timer expired on ring sdma0
[    9.545394] kfd kfd: amdgpu: Allocated 3969056 bytes on gart
[    9.545417] kfd kfd: amdgpu: Total number of KFD nodes to be created: 1
[   10.049267] amdgpu 0000:03:00.0: amdgpu: Fence fallback timer expired on ring sdma0
[   10.049402] amdgpu: Virtual CRAT table created for GPU
[   10.049521] amdgpu: Topology: Add dGPU node [0x7340:0x1002]
[   10.049523] kfd kfd: amdgpu: added device 1002:7340
[   10.049539] amdgpu 0000:03:00.0: amdgpu: SE 1, SH per SE 2, CU per SH 12, active_cu_number 20
[   10.049544] amdgpu 0000:03:00.0: amdgpu: ring gfx_0.0.0 uses VM inv eng 0 on hub 0
[   10.049546] amdgpu 0000:03:00.0: amdgpu: ring comp_1.0.0 uses VM inv eng 1 on hub 0
[   10.049547] amdgpu 0000:03:00.0: amdgpu: ring comp_1.1.0 uses VM inv eng 4 on hub 0
[   10.049548] amdgpu 0000:03:00.0: amdgpu: ring comp_1.2.0 uses VM inv eng 5 on hub 0
[   10.049549] amdgpu 0000:03:00.0: amdgpu: ring comp_1.3.0 uses VM inv eng 6 on hub 0
[   10.049550] amdgpu 0000:03:00.0: amdgpu: ring comp_1.0.1 uses VM inv eng 7 on hub 0
[   10.049550] amdgpu 0000:03:00.0: amdgpu: ring comp_1.1.1 uses VM inv eng 8 on hub 0
[   10.049551] amdgpu 0000:03:00.0: amdgpu: ring comp_1.2.1 uses VM inv eng 9 on hub 0
[   10.049552] amdgpu 0000:03:00.0: amdgpu: ring comp_1.3.1 uses VM inv eng 10 on hub 0
[   10.049553] amdgpu 0000:03:00.0: amdgpu: ring kiq_0.2.1.0 uses VM inv eng 11 on hub 0
[   10.049554] amdgpu 0000:03:00.0: amdgpu: ring sdma0 uses VM inv eng 12 on hub 0
[   10.049555] amdgpu 0000:03:00.0: amdgpu: ring sdma1 uses VM inv eng 13 on hub 0
[   10.049556] amdgpu 0000:03:00.0: amdgpu: ring vcn_dec uses VM inv eng 0 on hub 8
[   10.049557] amdgpu 0000:03:00.0: amdgpu: ring vcn_enc0 uses VM inv eng 1 on hub 8
[   10.049558] amdgpu 0000:03:00.0: amdgpu: ring vcn_enc1 uses VM inv eng 4 on hub 8
[   10.049559] amdgpu 0000:03:00.0: amdgpu: ring jpeg_dec uses VM inv eng 5 on hub 8
[   10.061446] amdgpu 0000:03:00.0: amdgpu: Runtime PM not available
[   10.061681] amdgpu 0000:03:00.0: amdgpu: [drm] Skipping amdgpu DM backlight registration
[   10.062153] amdgpu 0000:03:00.0: [drm] Registered 5 planes with drm panic
[   10.062155] [drm] Initialized amdgpu 3.64.0 for 0000:03:00.0 on minor 2
[   10.067637] fbcon: amdgpudrmfb (fb0) is primary device
[   10.067724] amdgpu 0000:03:00.0: [drm] fb0: amdgpudrmfb frame buffer device

$ xrandr 
Can't open display