[PLUG] External monitor remains black

Mon Nov 29 16:40:56 UTC 2010

On Mon, 29 Nov 2010 00:51:59 -0800
Jason Barnett <jason.barnett71 at gmail.com> dijo:

>You are in luck, I still have my old xorg.conf file that you can use
>as an example.
>
>The key is the* Option         "CustomEDID"
>"DFP-0:/etc/X11/VX2025WM-EDID.bin"* in the screen section of the
>xorg.conf combined with the binary (non-ascii) version of the edid
>file (named VX2025WM-EDID.bin in this example)

I have found the custom EDID option elsewhere while googling. 

>I verified that your monitor does have the correct checksum so I am
>not sure why it doesn't work correctly for you.  This is worth a try
>though. I am including the binary version of your edid that I typed
>in, just in case you only had the ascii version.

Thanks. I can't remember what utility I used to produce it, but I
remember it offered to create a binary or ASCII file, and I chose ASCII
so I could read it easily. 

>Also, I found this was what the problem was by examining my Xorg.0.log
>and searched for errors, have you looked there to see if it is
>complaining at all?

I hope I never have to read an Xorg.0.log file again. But in answer to
your question, the files are always clean, both now with the nouveau
driver and previously with the nVidia driver.

>To modify the edid on my monitor, I used a boot CD provided by
>ViewSonic to correct a similar problem and customized it for my
>purpose, I think I still have the ISO around if you are interested.
>It's only about 25 MB if I remember correctly.

Don't throw it away, as I might need it. However, it is the laptop
display that I need to get at the correct resolution, and in the
Xorg.0.log the nouveau driver sees it as an "IBM 2887." Not sure if
Viewsonic utility will work with it. In fact, the log file also gives
the EDID in hex:

 EDID (in hex):
[    23.567] (II) NOUVEAU(0): 	00ffffffffffff00244d872800000000
[    23.567] (II) NOUVEAU(0): 	000f0103802115780abca59858558b28
[    23.567] (II) NOUVEAU(0): 	24505400000001010101010101010101
[    23.567] (II) NOUVEAU(0): 	0101010101011c2f90d0601a0f402030
[    23.567] (II) NOUVEAU(0): 	13004bcf10000019452790d0601a0f40
[    23.567] (II) NOUVEAU(0): 	203013004bcf100000190000000f00b3
[    23.567] (II) NOUVEAU(0): 	0a32b30a28140100320c0000000000fe
[    23.567] (II) NOUVEAU(0): 	004c503135345730322d544c303600bf

The nouveau driver then produces modelines for 1680x1050, 1400x1050,
and lesser resolutions, all of which work fine. Presumably it did this
from the information in the above EDID. When the nVidia driver reads
the same EDID it complains that the horizontal and vertical sync rates
are wrong, says it is going to ignore them, and produces modelines just
for 1680x1050. If I add custom modelines to xorg.conf the nVidia driver
tries them, concludes they won't work, and discards them.

Working around other people's bugs is a PITA.

>On Sun, Nov 28, 2010 at 10:48 PM, John Jason Jordan
><johnxj at comcast.net>wrote:
>
>> In my peregrinations through the web I came across the possibility of
>> modifying the EDID in the monitor, as well as the possibility of
>> adding a line in xorg.conf to force the driver to read the EDID from
>> a file. The former can be done with a shareware tool called
>> Powerstrip. Unfortunately, it runs only on Windows, and I have no
>> Windows on the laptop. It is also scary.
>>
>> As for getting the EDID into a file, I did that with a utility called
>> monitor-edid. Here is the ASCII version:
>>
>> 00 ff ff ff ff ff ff 00 24 4d 87 28 00 00 00 00 00 0f 01 03 80 21 15
>> 78 0a bc a5 98 58 55 8b 28 24 50 54 00 00 00 01 01 01 01 01 01 01 01
>> 01 01 01 01 01 01 01 01 1c 2f 90 d0 60 1a 0f 40 20 30 13 00 4b cf 10
>> 00 00 19 45 27 90 d0 60 1a 0f 40 20 30 13 00 4b cf 10 00 00 19 00 00
>> 00 0f 00 b3 0a 32 b3 0a 28 14 01 00 32 0c 00 00 00 00 00 fe 00 4c 50
>> 31 35 34 57 30 32 2d 54 4c 30 36 00 bf
>>
>> Not very helpful, eh?
>>
>> I can get the physical properties of the laptop display with xrandr
>> (I think). But I don't know how to put them into a file that the
>> nVidia driver will be able to understand. If you can remember
>> anything about how you did it, I'd be interested.
>>
>>
>> On Sun, 28 Nov 2010 15:59:08 -0800
>> Jason Barnett <jason.barnett71 at gmail.com> dijo:
>>
>> >FYI, it is possible to force X to read the edid from a file instead
>> >of the monitor.  Had to do this for a couple of years with my
>> >Viewsonic monitor, finally I modified my monitor's firmware to
>> >match what the driver was wanting (different checksum) and have not
>> >had any problems sense.
>> >
>> >If you want details, let me know and I'll dig through my notes as I
>> >have forgotten the syntax for doing this..
>> >Jason
>> >
>> >On Sun, Nov 28, 2010 at 3:00 PM, John Jason Jordan
>> ><johnxj at comcast.net>wrote:
>> >
>> >> On Sun, 28 Nov 2010 13:55:32 -0800
>> >> Bill Barry <bill at billbarry.org> dijo:
>> >>
>> >> >On Sun, Nov 28, 2010 at 12:57 PM, John Jason Jordan
>> >> ><johnxj at comcast.net>wrote:
>> >> >
>> >> >> I want as much screen real estate as possible for my
>> >> >> presentation. The projector will project 1400x1050 and can
>> >> >> accept from my computer up to 1600x1200. Therefore, I want my
>> >> >> laptop to do 1400x1050 or higher, in a 4:3 ratio. The nVidia
>> >> >> driver offers me only 1680x1050, 1280x1050, or 1280x960, and
>> >> >> lower resolutions. Thus, with the nVidia driver I can project
>> >> >> 1680x1050, which will be distorted to the audience, or I can
>> >> >> project 1280x960, which will not be distorted to the audience,
>> >> >> but gives me less screen real estate than the projector is
>> >> >> capable of.
>> >> >>
>> >> >> The nouveau driver gives me options of 1680x1050 or 1400x1050,
>> >> >> and lesser resolutions. By setting my laptop to 1400x1050 I can
>> >> >> project an undistorted 1400x1050 to the audience. My laptop
>> >> >> will be slightly distorted, but I am looking at it right now
>> >> >> and it is tolerable. After the presentation I can set my
>> >> >> laptop back to 1680x1050.
>> >>
>> >> >So there is a problem getting the nVidia driver into the
>> >> >resolution you want and a problem getting the nouveau driver to
>> >> >display on two monitors. Why not reverse the problem. Go back to
>> >> >the nVidia driver at 1280x960 and get dual monitors working.
>> >> >Then try to find out why the nVidia driver is not offering you
>> >> >the resolution you want. It seems the resolution problem would
>> >> >be easier to solve.
>> >>
>> >> That is what I tried to do from the beginning. By reading
>> >> Xorg.0.log I finally determined that the nVidia driver was
>> >> misinterpreting the EDID data from the laptop screen. In other
>> >> words, fixing the resolution problem in the nVidia driver
>> >> required a bugfix from nVidia. Meantime, I knew that the nouveau
>> >> driver would give me the resolution I wanted because the Lucid
>> >> live CD uses the nouveau driver and it offered me 1400x1050. I
>> >> also knew that it was possible to get the nouveau driver to
>> >> connect to the projector because others have done so. And from
>> >> reading the troubleshooting page on nouveau's site I'm pretty
>> >> sure I can fix what is wrong. I've just had other things to do so
>> >> far today. But before the day is out I'll probably have the
>> >> external monitor working. (Crossing fingers.)
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>> >>
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