On Sat, Oct 03, 2026 at 03:15:23PM +0200, Miguel Mesa wrote:
> commit 7e5760f084d0 ("drm/amd/display: add HDMI 2.1 Compliance Support")
> selects YCbCr 4:2:0 for a 4:2:0-only mode only when the IGT override asks
> for it, and YCbCr 4:4:4 only when that override is YCbCr 4:4:4. On a
> normal boot the override is unset.
>
> A 3840x2160@60 mode that the sink lists only in the YCbCr 4:2:0 block
> then falls through to 4:4:4 or RGB, and the Wayland session cannot build
> the output layer: kwin_wayland_drm: Failed to create framebuffer (EINVAL)
> right after login. v7.3-rc5 selects 4:2:0 again for those modes when the
> color format is automatic. Do the same here, including HDMI FRL.
>
> Keep automatic YCbCr 4:4:4 for the other HDMI modes, as 7.1 did. The TMDS
> depth fallback also runs for HDMI FRL, so a mode that does not fit at
> 4:4:4 can still drop to 4:2:0.
>
> This is not a backport of a mainline commit. The 7.3 fix is the rewrite
> in 0b0ff65d3c ("drm/amd/display: Refactor stream validation"), which
> cannot be cherry-picked to 7.2;
Why not? What's preventing that? We'll gladly take large sets of
patches to fix bugs, in fact we prefer to.
> Jerry Zuo confirmed the pre-7.3 logic is
> gone there. This patch restores the pre-regression selection on the 7.2
> code, following the v7.3-rc5 rule. Mario Limonciello asked for it to be
> sent to stable in drm/amd#5760.
>
> Regression: black screen after login on HDMI sinks whose modes fall
> through to RGB, e.g. Strix Halo (gfx1151) + TCL 4K TV whose 3840x2160@60
> is YCbCr 4:2:0-only (VIC 97). 7e5760f084d0 shipped in 7.2; still unfixed
> in 7.2.9.
>
> Tested on CachyOS linux-cachyos-bore 7.2.7-3 (znver4) on that Strix Halo
> box: Plasma runs at 3840x2160@60 with the same userspace and firmware
> that stayed black on every stock 7.2.x kernel.
>
> Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5760
> Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5893
> Reported-by: Michał Górny <[email protected]>
> Reported-by: Miguel Mesa <[email protected]>
> Suggested-by: Mario Limonciello <[email protected]>
> Tested-by: Miguel Mesa <[email protected]>
> Signed-off-by: Miguel Mesa <[email protected]>
> Co-authored-by: Cursor <[email protected]>
A bot can not be an author. Please read the documentation for how to
use a LLM in the kernel.
thanks,
greg k-h
