Hi, There's a regression reported that HDMI output stops working after os upgrade: https://bugs.launchpad.net/bugs/1871721 Here's the bisect result: 0519c102f5285476d7868a387bdb6c58385e4074 is the first bad commit commit 0519c102f5285476d7868a387bdb6c58385e4074 Author: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Date: Mon Jan 22 19:41:31 2018 +0200 drm/i915: Implement display w/a #1143 Apparently SKL/KBL/CFL need some manual help to get the programmed HDMI vswing to stick. Implement the relevant workaround (display w/a #1143). Note that the relevant chicken bits live in a transcoder register even though the bits affect a specific DDI port rather than a specific transcoder. Hence we must pick the correct transcoder register instance based on the port rather than based on the cpu_transcoder. Also note that for completeness I included support for DDI A/E in the code even though we never have HDMI on those ports. v2: CFL needs the w/a as well (Rodrigo and Art) Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> Cc: Art Runyan <arthur.j.runyan@xxxxxxxxx> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20180122174131.28046-1-ville.syrjala@xxxxxxxxxxxxxxx Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> dmesg from drm-tip with drm.debug=0xe can be found here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comments/64 Kai-Heng _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
