[Bug 105854] GLK: HDMI output does not resume after DPMS OFF with DMC loaded

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=105854

--- Comment #3 from Imre Deak <imre.deak at intel.com> ---
Created attachment 138558
  --> https://bugs.freedesktop.org/attachment.cgi?id=138558&action=edit
Fix HDMI TMDS enabling

> Issue started occur with commit 069d40f5834ad26a58f269225a7e13af17019062

I was able to repro the problem on my GLK and can confirm that reverting the
above fixed it. What this commit does is in practice enable DC5 (w/o it DMC
will never enter DC5 even though it's enabled and all conditions for DC5 are
met).

The HDMI output on my RVP is wired through an onboard LSPCON adapter and it
seems it has problem accepting the first I2C write to enable the TMDS output
buffer after a DC5 entry/exit sequence. Attached is a patch that fixes this,
could you Clint try if it gets rid of the problem? If it does please check the
number of write attempts, for me it was always the second write that succeeded.

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