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.syrj...@linux.intel.com>
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.v...@intel.com>
Cc: Art Runyan <arthur.j.run...@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
Link:
https://patchwork.freedesktop.org/patch/msgid/20180122174131.28046-1-ville.syrj...@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.v...@intel.com>
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
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