Xorg video resolution depends on display?

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Flash
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Xorg video resolution depends on display?

#1 Post by Flash »

I don't know if this is a bug. It seems like one to me.

I have a Viewsonic N3250W LCD display, which has a maximum resolution of 1360 x 768. My neighbor has some other brand of plasma display but which has the same maximum resolution.

While showing off her new display, my neighbor had mentioned she would like to use it as a computer monitor. I have several old computers gathering dust, so I told her I'd see if one would do what she wanted. First I connected it to my LCD display, to test it and to set up a multisession Puppy DVD for her. Xorg reported that my display was capable of 1360 x 768 but that the video card (on-board Intel 815) might not be. Sure enough, the maximum resolution that would work was 1024 x 768 (or something like that.)

Imagine my surprise when the same computer worked my neighbor's 1360 x 768 plasma display at its full resolution.

Can anyone suggest why Xorg works my neighbor's display at 1360 when it will only work mine at 1024, using the same computer?

(By the way, my neighbor took to Puppy like a duck to water. :D )

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Béèm
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#2 Post by Béèm »

[OT]
Is your neighbor female? :wink:
[/OT]

Seriously now, I can't see a reason why this is so.
Bad connection when you tried at home?
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Leachim
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#3 Post by Leachim »

It might depend on the video driver. Look for the Driver-entry in the Device-Section of xorg.conf. Some drivers do only support resolutions with 4:3 ratios.

Another problem might araise from missing information about the display. Try ddcprobe on both displays. This will show you what possible resolutions the displays report.

I'm interested in gathering as much information about (problematic) graphics adapter / display combinations as possible for the "New X-Wizard" project. (see: http://www.murga-linux.com/puppy/viewtopic.php?t=23468)

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Flash
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#4 Post by Flash »

Thanks, leachim. I'll post the results of ddcprobe to this thread as soon as I can run it on both displays from the computer in question. It will be from Puppy 3.01, as ddcprobe locked up my computer when I ran it in Dingo 392. :(

Is there any other information you would like as well?
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#5 Post by Leachim »

If you could dowload lspci and the pci-hardware-description file as described in my X-Wizard thread and then run lspci and ddcprobe and post the results this would be absolutely great! :D

Bruce B

#6 Post by Bruce B »

Flash,

See what you can learn about the 915resolution hack included with Puppy.

It's made for those cards, I don't have an equivalent card to test with, but I think it's supposed to solve problems of this nature.

Run on CLI 915resolution

For starters, the maybe Google for more specifics.

Bruce

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Flash
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#7 Post by Flash »

Results of running ddcprobe in Puppy Dingo4 alpha3 on a Gigabyte GA-MA69GM-S2H motherboard with onboard video, connected to my Viewsonic N3250w display via HDMI:
  • # ddcprobe
    vbe: VESA 3.0 detected.
    oem: ATI ATOMBIOS
    vendor: (C) 1988-2005, ATI Technologies Inc.
    product: RS690 01.00
    memory: 16384kb
    mode: 640x400x256
    mode: 640x480x256
    mode: 800x600x256
    mode: 1024x768x256
    mode: 1280x1024x256
    mode: 640x480x64k
    mode: 800x600x64k
    mode: 1024x768x64k
    mode: 1280x1024x64k
    mode: 320x200x64k
    mode: 1600x1200x256
    mode: 1600x1200x32k
    mode: 1600x1200x64k
    edid:
    edid: 1 3
    id: 101c
    eisa: VSC101c
    serial: dadb6101
    manufacture: 46 2005
    input: analog signal.
    screensize: 70 39
    gamma: 2.200000
    dpms: RGB, active off, no suspend, no standby
    timing: 720x400@70 Hz (VGA 640x400, IBM)
    timing: 640x480@60 Hz (VGA)
    timing: 640x480@75 Hz (VESA)
    timing: 800x600@75 Hz (VESA)
    timing: 1024x768@87 Hz Interlaced (8514A)
    timing: 1024x768@75 Hz (VESA)
    ctiming: 1280x1024@60
    ctiming: 640x640@70
    dtiming: 1360x768@70
    monitorserial: PS40546C0807
    monitorrange: 30-64, 60-75
    monitorname: N3250w
    #
My neighbor is gone until after Christmas so it will be a while before I can run ddcprobe on her display.

raffy
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915resolution

#8 Post by raffy »

The 915resolution trick is being discussed here:
http://murga-linux.com/puppy/viewtopic.php?t=24814

What it does is to run this in console: 915resolution -l
(that's an L)

and then pick a number for assigning your chosen resolution (38 has been suggested for 800 px wide resolution): 915resolution 38 xxx yyy colordepth. For my example, I used 915resolution 43 800 480 16
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Dougal
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Re: Xorg video resolution depends on display?

#9 Post by Dougal »

Flash wrote:Can anyone suggest why Xorg works my neighbor's display at 1360 when it will only work mine at 1024, using the same computer?
It might have to do with the refresh-rates your screen works at: the xorgwizard makes a very conservative estimate of the rates, but in some cases it might be wrong.
Some LCD screens work at 20 Hz (or whatever it is), while Puppy usually won't allow it to go beneath 30 or something.
There's also the matter of 1360 vs 1366 and all that -- I can't remember the details now...
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