[Bug 100226] [KBL] Switching multihead mode fails

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=100226

--- Comment #10 from qwang13 <quanxian.wang at intel.com> ---
After working with Aaron, we have reproduced the issue and get the log. From
the log we found:

Case: extend mode - > mirror mode

Bad machine (Raven-2) hdmi connector is unplugged after the change.
This is the key point. With this mode change, HDMI module is crashed, and
unplugged. And after a while, HDMI is reconnected again with new plug event. We
got all the hot-plug events. Also the log shows that process.

Raven-2 has a complete different HDMI hardware module design which uses
TBT(thunderbolt) IC to control DP/HDMI/Type-C connector. With general process,
Thai-2 (good machine) works normal with normal HDMI connector. But with same
process on Raven-2,
The control signal and data from graphics kernel driver will be firstly
directed to TBT IC and then to HDMI connector. The issue happens on TBT IC
signal/data transfer. HDMI is lost when kernel driver send data to TBT IC.

Suggestion:
We need TBT IC designer to double confirm, what happens in IC? HDMI is
unplugged under some case. We are doubt in some case, TBT IC doesn't follow
interface defined in HDMI spec. Need hardware design engineer to track why this
happens on Raven-2.

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