[Bug 33011] HDMI-A-1 Does not work after resume (But claims it does)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=33011

--- Comment #17 from Alex Deucher <agd5f at yahoo.com> 2011-02-04 09:13:44 PST ---
(In reply to comment #16)
> Just a few followups. It doesn't seem to be related to the docking station
> switching. The problem occurs even without the docking port.
> 
> Additionally, if I plug an HDMI cable into the laptop while the docking station
> is plugged in, the monitor is not detected at all. Where-as after I resume and
> have a problem, the monitor is detected, it just doesn't get sync. So the
> docking station switching disables the port "more" than the resume problem.

This is consistent with the gpio controlled data and ddc routing that I suspect
is happening.  There's probably a small mux which routes the ddc/hdp lines (for
detection and edid) and the data lines (for the actual video signal) between
the HDMI port on the laptop and the DVI port on the docking station.  When you
dock, the acpi docking method probably calls some other method which switches
the mux to the other connector.  The same thing probably happens on undock. 
The question is, is this handled by an acpi method or some platform specific
gpio/i2c setup.  Newer radeon-based laptops that use a mux like this have a
special entry in the vbios object table that describes the mux.  Unfortunately,
your system doesn't have this, so it's probably some system-specific
configuration.  When you suspend, the mux loses power and goes into some
undefined state on resume the signals are not routed correctly since the mux
state is wrong.

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