[Bug 59841] [IVB cpu eDP] panel is broken due to 657445fe86 (eDP bpp clamping)

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=59841

--- Comment #89 from jkp <jkp at iki.fi> ---
>From Daniel's commit message at
http://o.cs.uvic.ca:20810/perl/cid.pl?cid=657445fe8660100ad174600ebfa61536392b7624:

"It's an ugly hack for a Haswell SDV platform where the vbt doesn't
seem to fully agree with the panel. Since it seems to cause issues on
real eDP platform let's just kill this hack again."

.. this seems to confirm the issue is that some (TX300, Asus UX32VD, Dell
XPS13, a Haswell SDV platform) (call them type A) give bogus info for bpp in
edp vbt data in UEFI mode. To be more specific, they give 18 bpp (value of 0 in
color_depth) when the value should be 24 (value 1). But for some other
machine(s?) (type B), 18 given by vbt data is the value which must be used, and
thus the code currently in 3.11-rc7 is needed for type B machines.

So, we'd need a way to recognize either type A or type B machines (or both),
and modify behaviour accordingly. If only one class can be recognized, make the
default behaviour to be the one for the other class.

Correct?

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the assignee for the bug.