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            <b><a class="bz_bug_link 
          bz_status_ASSIGNED "
   title="ASSIGNED - [GLK] no signal after switch resolution from 1080p@23.98"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=105887#c110">Comment # 110</a>
              on <a class="bz_bug_link 
          bz_status_ASSIGNED "
   title="ASSIGNED - [GLK] no signal after switch resolution from 1080p@23.98"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=105887">bug 105887</a>
              from <span class="vcard"><a class="email" href="mailto:d.scheller.oss@gmail.com" title="Daniel Scheller <d.scheller.oss@gmail.com>"> <span class="fn">Daniel Scheller</span></a>
</span></b>
        <pre>(In reply to Clinton Taylor from <a href="show_bug.cgi?id=105887#c109">comment #109</a>)
<span class="quote">> > Maybe the connector check causes the
> > initial issue here?

> Daniel,
>    Using the v3 patch could you apply the following diff?</span >

Did that (exact diff looks like [1] now, please ignore the debchangelog stuff).
Packaged ([2]), installed, rebooted, issue still remains. The
DRM_ERROR(connector_type) reveals why, though:

# dmesg | grep disable_transcoder
[    2.998161] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 1024
[   11.002233] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64
[  373.751818] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64
[  380.119446] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64
[  383.988156] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64
[  389.564144] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64
[  406.176236] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64
[  415.329143] [drm:intel_ddi_disable_transcoder_func [i915]] *ERROR*  ***
connector type = 64

So, right after boot, connector type is INTEL_OUTPUT_UNKNOWN, and in all
following cases it's INTEL_OUTPUT_HDMI. I did not test this yet, but adding
_UNKNOWN to the if() should finally do the trick (will eventually add that
somewhen today and retest).

[1]
<a href="https://github.com/herrnst/ubuntu-bionic-kernel/commit/38ecb48f10b4dfedc1dd190d42749cb0d93b6886">https://github.com/herrnst/ubuntu-bionic-kernel/commit/38ecb48f10b4dfedc1dd190d42749cb0d93b6886</a>
[2]
<a href="https://github.com/herrnst/ubuntu-bionic-kernel/tree/4.15.0-24.26-glktesting5-deb">https://github.com/herrnst/ubuntu-bionic-kernel/tree/4.15.0-24.26-glktesting5-deb</a></pre>
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