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* [Intel-gfx] [Regression] "drm/i915: Implement display w/a #1143" breaks HDMI on ASUS GL552VW
@ 2020-08-13  4:07 Kai-Heng Feng
  2020-08-13 16:50 ` Vivi, Rodrigo
  0 siblings, 1 reply; 17+ messages in thread
From: Kai-Heng Feng @ 2020-08-13  4:07 UTC (permalink / raw)
  To: Ville Syrjälä, Rodrigo Vivi, arthur.j.runyan; +Cc: intel-gfx

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@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.vivi@intel.com>
    Cc: Art Runyan <arthur.j.runyan@intel.com>
    Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20180122174131.28046-1-ville.syrjala@linux.intel.com
    Reviewed-by: Rodrigo Vivi <rodrigo.vivi@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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^ permalink raw reply	[flat|nested] 17+ messages in thread

end of thread, other threads:[~2021-04-07 14:34 UTC | newest]

Thread overview: 17+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-13  4:07 [Intel-gfx] [Regression] "drm/i915: Implement display w/a #1143" breaks HDMI on ASUS GL552VW Kai-Heng Feng
2020-08-13 16:50 ` Vivi, Rodrigo
2020-08-13 17:56   ` Runyan, Arthur J
2020-08-14  5:13     ` Kai-Heng Feng
2020-08-16 16:22       ` Runyan, Arthur J
2020-08-17  6:17         ` Kai-Heng Feng
2020-08-24 18:04           ` Ville Syrjälä
2020-08-24 18:46             ` Runyan, Arthur J
2020-08-26  4:40               ` Kai-Heng Feng
2020-08-26 13:05                 ` Ville Syrjälä
2020-09-03  6:26                   ` Kai-Heng Feng
2020-10-13  5:20                     ` Kai-Heng Feng
2020-10-13 11:15                       ` Ville Syrjälä
2020-10-13 11:50                         ` Saarinen, Jani
2020-10-13 12:18                           ` Kai-Heng Feng
2020-10-13 12:25                             ` Saarinen, Jani
2021-04-07 14:34                         ` Rodrigo Vivi

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