[PATCH 0/1][Unstable/OEM-5.10] UBUNTU: SAUCE: Fix the video can't output through WD19TB connected with TGL platform during cold-boot

[Koba Ko]

BugLink: https://bugs.launchpad.net/bugs/1910211

[Impact]
After Apply the patches from https://www.spinics.net/lists/intel-gfx/msg248700.html, 
the TGL platform would have the failure rate(1/20) on outputting the video through WD19TB.

[Fix]
The patch is provided by Imre(https://gitlab.freedesktop.org/drm/intel/-/issues/2801#note_740352).
If there's no lttpr in the link chain, the DRM driver wouldn't configure the transparent mode again.

[Test Case]
1. Connected the WD19TB with the TGL platform and
connected the external monitor on WD19TB with HDMI/Displayport.
2. Don't plug the external monitor on the TGL platform, so there's only one monitor on WD19TB.
3. Cold boot the TGL platform.
4. Check the monitor can be blinked and the video can output to the monitor.

[Where problems could occur]
As per Imre's comment, this may be caused by the dock.
In the future if the WD19TB's firmware is updated, we may encounter the same issue again.


Imre Deak (1):
  UBUNTU: SAUCE: drm/i915/dp: Prevent setting LTTPR mode if no LTTPR is
    detected

 .../drm/i915/display/intel_dp_link_training.c | 36 ++++++++-----------
 1 file changed, 15 insertions(+), 21 deletions(-)

-- 
2.25.1