[haiku-bugs] Re: [Haiku] #5221: [intel_extreme] implement DVI support
- From: "pulkomandy" <trac@xxxxxxxxxxxx>
- Date: Sat, 13 Sep 2014 08:16:34 -0000
#5221: [intel_extreme] implement DVI support
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Reporter: diver | Owner: axeld
Type: enhancement | Status: new
Priority: normal | Milestone: R1
Component: Drivers/Graphics/intel_extreme | Version: R1/Development
Resolution: | Keywords:
Blocked By: | Blocking: 7662
Has a Patch: 1 | Platform: All
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Comment (by pulkomandy):
A little bit of history here: originally the intel driver only polled
GPIOs on line A for EDID. This didn't work on my laptop (Dell Inspiron
1525) and during BeGeistert 2009 Axel helped me debug this and we added
polling line C to fix this one machine. However, this also broke things on
some other setups.
The current solution is to scan both lines A and C, and if we find
something there, we use it. If no EDID data is found there, we have a
fallback solution, which consists of reusing the EDID from VESA. This was
later extended with extracting information about the LVDS panel directly
from the Intel VGA BIOS.
As a result on my new Core-i3 machine:
- HDMI output is working fine, using EDID from VESA
- VGA is not working (black screen)
- I did not test DVI, no appropriate cable available
- If I have both HDMI and VGA plugged, the EDID is read from the VGA port
and applied to the HDMI one. This results on misaligned screen (about 1/3
of the screen is left black, and remaining part of the picture is shifted
so DeskBar is somewhere on the middle of the screen). Still no VGA output.
So I don't know if scanning all ports is a good idea, in the current state
the VESA/VBT probing is getting the right resolution in most cases. It has
the downside that it only adds a single mode and does not know the exact
display timing constraints, however.
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Ticket URL: <https://dev.haiku-os.org/ticket/5221#comment:14>
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