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 Booting with HDMI-DVI adapter issues 
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Joined: Sat Feb 25, 2012 11:08 pm
Posts: 5
Post Booting with HDMI-DVI adapter issues
Hi everyone.

My question might be newbie or not I am not sure, I am not super proficient in linux OS.

Recently one of my friends was in need of a simple machine to watch movies and basic browsing on his bedroom TV. I gave hime happily my old fit pc2 (I have a V3 now) knowing that it would do a do job, but it didn't.

Here is the issue:
When booting with a HDMI cable everything is OK, the pc boots and al works, but when the HDMI-DVI adapter is used (the one originally provided) it freaks out, the TV displays an "unsupported resolution" error when reaching the desktop GUI (i can see the earlier stages of the boot).
I though it was a limitation with the TV (a weird Chinese model) but I the same issue using my high end Dell screen that support pretty much any resolution/frequency.
I thought the adapter might be broken, but if I boot on HDMI and then switch to the adapter it works fine.

As it was an old install I thought the drivers etc might be screwed so i took advantage of the newly released EMGD 1.16 and did the whole thing.
Success on the install but only marginal success on fixing the problem:
Sometimes now on the Dell monitor it works, but the resolution is locked to 1920 @ 60Hz.
I know the TV support 1920x1080 @ 30 Hz and 720 at many frequencies (selectable when I boot with the HDMI cable)

Does anyone have a clue on what it might be, or actually how to fix it ?

A few notes :
- Sometimes after failing a boot with DVI on the next boot I get a error message about some incorrect permissions to write a config file.
- Being in China Internet at boot doesn't always work straight away meaning I cannot ssh / remote screen into the box
- (related or not )I tried using a very strange DVI to YHB adapter, It kind of works but the resolution is locked to a very unusable value


thanks.


Sat Jan 12, 2013 5:14 am
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Joined: Mon Mar 16, 2009 2:11 pm
Posts: 2339
Post Re: Booting with HDMI-DVI adapter issues
I believe the DDC negotiation between the fit-PC2 display driver and the display does not result in usable resolution.

How do you use hdmi2dvi to connect to a TV? TVs rarely have dvi input. Maybe you mean fit VGA adapter?

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Irad Stavi
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Sat Jan 12, 2013 8:31 am
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Joined: Sat Feb 25, 2012 11:08 pm
Posts: 5
Post Re: Booting with HDMI-DVI adapter issues
Yes its DVI, this Chinese TV (brand TCL) has many inputs including VGA, DVI, HDMI etc.
I could try to use the HDMI but then I cannot get the sound (as the TV expects the sound via HDMI and you cannot force another input for sound).

Is there a way to lock the default resolution ?


Sat Jan 12, 2013 2:58 pm
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Joined: Mon Mar 16, 2009 2:11 pm
Posts: 2339
Post Re: Booting with HDMI-DVI adapter issues
DDC / EDID can usually be disable by editing xorg.conf.
You can check the discussions here
viewforum.php?f=34

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Irad Stavi
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Sat Jan 12, 2013 3:21 pm
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Joined: Sun Apr 26, 2009 3:24 pm
Posts: 298
Post Re: Booting with HDMI-DVI adapter issues
xorg.conf manual available at the Intel website:
https://edc.intel.com/Download.aspx?id= ... fault.aspx

There is a Linux part under "7.4 Configuring Linux" topic. You can disable EDID and set desired static resolution.

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Tue Jan 15, 2013 8:36 am
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Joined: Sat Feb 25, 2012 11:08 pm
Posts: 5
Post Re: Booting with HDMI-DVI adapter issues
Thanks for the answers. Should have some time over the week end to try this.
Will post the outcome.


Sat Jan 26, 2013 2:30 am
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Joined: Sat Feb 25, 2012 11:08 pm
Posts: 5
Post Re: Booting with HDMI-DVI adapter issues
So one afternoon later problem half solved.

I tried tweaking the xorg.conf but not much success, I actually manage to lock myself out of any resolution including the console modes.
At some point I must have done a mistake because I have overwritten my backup xorg.conf with a corrupted one.
Using the dell screen I managed to get back in and reverted the xorg.conf to what I thing was the initial configuration.

I changed the adapted using a more basic one (from an old ATI card) and I manage to boot in a decent (if not optimal) resolution, however the console screens (ctrl +alt+ F2 etc) are in impossible resolution (I think they are in 800X1200 ).
Also it detects a range of available resolution that are not supported by the TV (frequencies issues).

So this was scary enough for a week or two I'd say, I will not dive in this until after chinese new year, but I'd like to get to the end of the issue.

I have seen in the intel doc these lines in an example :
{code}
Option “ALL/1/Port/2/Dtd/1/PixelClock” “108000”
Option “ALL/1/Port/2/Dtd/1/HorzActive” “1280”
Option “ALL/1/Port/2/Dtd/1/HorzSync” “48”
Option “ALL/1/Port/2/Dtd/1/HorzSyncPulse” “112”
Option “ALL/1/Port/2/Dtd/1/HorzBlank” "408"
Option “ALL/1/Port/2/Dtd/1/VertActive” "1024"
Option “ALL/1/Port/2/Dtd/1/VertSync” "1"
Option “ALL/1/Port/2/Dtd/1/VertSyncPulse” “3”
{code}

is this the type of things to use for the default configuration ?
I have only added a display subsection in the screen section without any effect it seems.
Overall the explanation on the intel doc are not very good, or rather way beyond my low level skills.

cheers


Sun Jan 27, 2013 11:32 am
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Joined: Sun Apr 26, 2009 3:24 pm
Posts: 298
Post Re: Booting with HDMI-DVI adapter issues
Yes, you are on the rigth way. Also you must play with EDID behavior options, for example this should use your custom timings (DTD) only in case EDID was detected or not:
Code:
Option     "ALL/1/Port/2/General/Edid"           "1"
Option     "ALL/1/Port/2/General/EdidAvail"      "4"
Option     "ALL/1/Port/2/General/EdidNotAvail"   "4"


Here is snippet from the Intel's guide:
Code:
• Edid
This boolean key enables (set to 1) or disables (set to 0) the EdidAvail and
EdidNotAvail keys.
• EdidAvail and EdidNotAvail
These two 16-bit keys control the available timings for the display. If an EDID is
successfully read from the display device, then Intel® EMGD uses the EdidAvail flag
to determine what timings are available. Otherwise, if an EDID cannot be read,
then Intel® EMGD uses the EdidNotAvail key.
Bit #
Value (0 or 1)
0 Disable/Enable driver built-in timings
1 Disable/Enable EDID timings. (Only valid for
 the EdidAvail flag)
2 Disable/Enable DTD
3-15
Reserved


You must add these EDID lines and your custom timings in our xorg.conf under Section "Device" after
Code:
Option     "ALL/1/Port/2/General/name"           "DVI"
# Your EDID and DTD changes here

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Mon Jan 28, 2013 8:15 am
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