Hi,
Bug report for linux-firmware: the sienna_cichlid_dmcub.bin blob shipped in
recent Ubuntu noble packaging (linux-firmware 20240318.git3b128b60-0ubuntu2.29)
fails to load on a Radeon RX 6900 XT (Navi 21, DCN 3.0).
Hardware: Gigabyte B550 AORUS PRO AC, AMD Radeon RX 6900 XT (Navi 21),
ultrawide 3440x1440@144Hz on DisplayPort, 1920x1080 on HDMI.
Symptom: after upgrading linux-firmware 0ubuntu2.27 -> 0ubuntu2.29 and
rebooting, the right half of the DisplayPort ultrawide is black. The hardware
cursor remains visible on the black area; windows dragged there disappear.
After power-cycling the monitor it reports "no display found". xrandr output
toggles fail with "enabling link 0 failed: 15" and REG_WAIT timeouts
(mpc2_assert_idle_mpcc, hubp2_set_blank_regs). HDMI unaffected.
Kernel-independent: reproduces identically on 7.0.0-28 and 7.0.0-29.
Boot log (broken, every boot on 0ubuntu2.29):
[drm] Loading DMUB firmware via PSP: version=0x01000000
[drm] Wait for DMUB auto-load failed: 3
[drm] DMUB hardware initialized: version=0x01000000
Boot log (working, pre-upgrade on 0ubuntu2.27):
[drm] Loading DMUB firmware via PSP: version=0x02020020
(no errors)
Root cause analysis: 0ubuntu2.29 ships /lib/firmware/amdgpu/sienna_cichlid_dmcub.bin.zst
as a standalone 37,726-byte blob. In 0ubuntu2.26 (and the working layout) it
was a symlink to beige_goby_dmcub.bin.zst (74,553 bytes). The new 37KB blob
fails to auto-load (error 3) and amdgpu falls back to the silicon ROM DMUB
(version 0x01000000), which lacks the feature set (DSC, link training)
required for this output.
Workaround (confirmed 2026-08-18): replace sienna_cichlid_dmcub.bin.zst with
a symlink to beige_goby_dmcub.bin.zst, hold linux-firmware, reboot. Display
fully restored (DMUB 0x02020020, 144Hz, both monitors).
Upstream history for amdgpu/sienna_cichlid_dmcub.bin already contains
"amdgpu: Revert sienna cichlid dmcub firmware update" (2024-08-26) - a
previous revert of this blob. The current upstream main blob is ~114KB, also
not the 37KB one shipped in 0ubuntu2.29; the 37KB blob appears to be a stale
or bad intermediate version.
Request: restore the sienna_cichlid_dmcub.bin -> beige_goby_dmcub.bin symlink
in the tree, or sync the current upstream blob.
Happy to provide full dmesg/journal excerpts or test a candidate blob.
Best regards,
DaVinci
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