On Sat, 11 Jul 2026 14:35:30 -0500 Lionso Alejandro Pacheco Vacacela <[email protected]> wrote: [...] > Since the 7.1.x kernels, systems with AMD CIK/GCN1.1 APUs (Kaveri, > Kabini, Mullins) that use the analog VGA output get no display signal > at all: the monitor enters power save at KMS takeover and never wakes. > The machine is otherwise healthy (reachable over SSH). 7.0.x kernels > are fine. [...] > Root cause (upstream): Linux 7.1 switched CIK APUs to the amdgpu DC > display stack by default (c81f35cdbab2 "drm/amdgpu: Use DC by default > on CIK APUs"). DC's support for the NUTMEG bridge requires forcing the > DP link rate to HBR, but upstream commit > > a62346043a89 ("drm/amd/display: Fix coding style issue") > > inadvertently broke that quirk (the preferred link rate is no longer > applied to the link setting the algorithm iterates from), so DP link > training against the bridge fails at RBR and the output stays dark: > > [drm] enabling link 2 failed: 15 (DC_FAIL_DP_LINK_TRAINING) > > Upstream fix: "drm/amd/display: Fix preferred link rate for NUTMEG" by > Timur Kristóf, > https://lore.kernel.org/amd-gfx/[email protected]/ > Reviewed-by: Fangzhi Zuo, applied to the amdgpu maintainer tree on > 2026-07-10; not yet in mainline or 7.1.y at the time of writing. Also > tracked as https://gitlab.freedesktop.org/drm/amd/-/issues/5465. [...]
This ended up as commit 9fb646bc4d87f62bcbf0a7ea326430eb802c475c in 7.2-rc4. Please queue it up for 7.1-stable. Ben. -- Ben Hutchings Experience is what causes a person to make new mistakes instead of old ones.
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