Hi,
I’m running on Ubuntu 22.04 (Wayland session) with an AMD GPU, and I’ve encountered some confusing display mode behavior.
In my dmesg logs, the kernel probes and lists these display modes for my monitor:
[ 8.515963] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 240 2376000 3840 4088 4120 4400 2160 2163 2168 2250 0x48 0x9
[ 8.515969] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 120 1188000 3840 4016 4104 4400 2160 2168 2178 2250 0x48 0x5
[ 8.515974] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 60 594000 3840 4016 4104 4400 2160 2168 2178 2250 0x48 0x5
[ 8.515978] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 120 1188000 3840 4016 4104 4400 2160 2168 2178 2250 0x40 0x5
[ 8.515983] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 120 1186813 3840 4016 4104 4400 2160 2168 2178 2250 0x40 0x5
[ 8.515987] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 60 594000 3840 4016 4104 4400 2160 2168 2178 2250 0x40 0x5
[ 8.515991] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 60 593407 3840 4016 4104 4400 2160 2168 2178 2250 0x40 0x5
[ 8.515996] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 30 297000 3840 4016 4104 4400 2160 2168 2178 2250 0x40 0x5
[ 8.516000] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "3840x2160": 30 296703 3840 4016 4104 4400 2160 2168 2178 2250 0x40 0x5
[ 8.516004] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "2560x1440": 240 1036000 2560 2688 2720 2880 1440 1443 1448 1499 0x40 0x9
[ 8.516008] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "2560x1440": 120 497750 2560 2608 2640 2720 1440 1443 1448 1525 0x40 0x9
[ 8.516013] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "2560x1440": 60 241500 2560 2608 2640 2720 1440 1443 1448 1481 0x40 0x9
[ 8.516017] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1200": 240 2376000 1920 4088 4120 4400 1200 2163 2168 2250 0x40 0x9
[ 8.516021] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 240 597000 1920 2028 2060 2200 1080 1083 1088 1131 0x40 0x9
[ 8.516025] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 120 297000 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 8.516029] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 120 297000 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 8.516034] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 120 296703 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 8.516038] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 8.516042] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 8.516046] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 60 148352 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
[ 8.516050] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1920x1080": 50 148500 1920 2448 2492 2640 1080 1084 1089 1125 0x40 0x5
[ 8.516054] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1600x1200": 240 2376000 1600 4088 4120 4400 1200 2163 2168 2250 0x40 0x9
[ 8.516058] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1680x1050": 60 146250 1680 1784 1960 2240 1050 1053 1059 1089 0x40 0x6
[ 8.516063] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1600x900": 60 108000 1600 1624 1704 1800 900 901 904 1000 0x40 0x5
[ 8.516067] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1280x1024": 60 108000 1280 1328 1440 1688 1024 1025 1028 1066 0x40 0x5
[ 8.516071] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1440x900": 60 106500 1440 1520 1672 1904 900 903 909 934 0x40 0x6
[ 8.516075] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1280x800": 60 83500 1280 1352 1480 1680 800 803 809 831 0x40 0x6
[ 8.516080] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1280x720": 60 74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 8.516084] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1280x720": 60 74250 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 8.516088] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1280x720": 60 74176 1280 1390 1430 1650 720 725 730 750 0x40 0x5
[ 8.516092] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "1024x768": 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 8.516096] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "800x600": 60 40000 800 840 968 1056 600 601 605 628 0x40 0x5
[ 8.516100] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "720x480": 60 27027 720 736 798 858 480 489 495 525 0x40 0xa
[ 8.516105] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "720x480": 60 27000 720 736 798 858 480 489 495 525 0x40 0xa
[ 8.516109] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "640x480": 60 25200 640 656 752 800 480 490 492 525 0x40 0xa
[ 8.516113] amdgpu 0000:c4:00.0: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] Probed mode: "640x480": 60 25175 640 656 752 800 480 490 492 525 0x40 0xa
However, there’s no mention of 3840x2160 @ 144 Hz among the probed modes.
Despite that, 3840x2160 144hz is listed in the gnome-control-center and can be applied:
[ 39.166966] amdgpu 0000:c4:00.0: [drm:drm_atomic_set_mode_prop_for_crtc [drm]] Set [MODE:3840x2160_144.00] for [CRTC:85:crtc-0] state 000000007fd4f9ec
This suggests that GNOME (or userspace) selected and applied a 4K@144Hz mode that the kernel didn’t advertise.
My questions:
- Why is 3840x2160@144Hz being listed and set, even though it’s not in the kernel’s probed mode list?
- Is GNOME generating additional modes internally, or is it coming from somewhere else?
Additionally, when I select 3840x2160 @ 144 Hz from GNOME Settings, the screen goes black and this behavior is seen in Ubuntu 25 as well.
Any insight on why this mode is being exposed and why it fails silently would be appreciated.
Thanks!