Video projector not detected anymore (under Xorg 1.18.4)

Łukasz Maśko ed at
Thu Nov 3 15:12:45 UTC 2016

Dnia czwartek, 3 listopada 2016 15:41:52 Philippe Dosch pisze:
> Hi Folks,
> I'm assistant professor and I teach with the same video projectors
> since years (with each of the last three kubuntu releases on my
> laptop). I have a strange trouble since my last kubuntu update (2
> weeks ago). Now I'm under kubuntu 16.10, with a 1.18.4 Xorg server:

I have exactly the same problem and it lies in the kernel itself, probably in 
i915 driver, not in X. The change was introuced in kernel 4.7.0, the last of 
the 4.6.x line (4.6.7) works fine. The changes deal with detection of external 
Display Port and as a result I get first an error like this:

[drm:intel_dp_start_link_train [i915]] *ERROR* failed to update link training

at the kernel start (visible in dmesg). And then this output is not recognized 
anymore. I have filed a bug report
Maybe you can confirm it or append yours so we make developers fix this? I 
have no idea how to fix this myself. I'm just keeping kernel 4.6.7 to use when 
I want to do my presentations.
Łukasz Maśko                                                            _o)
Lukasz.Masko(at)                                           /\\
Registered Linux User #61028                                           _\_V
Ubuntu: staroafrykańskie słowo oznaczające "Nie umiem zainstalować Debiana"

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