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Thread: KMS on Thinkpad W500 + HP ZR22w monitor: no picture with DisplayPort, but DVI works.

  1. #1
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    Oct 2007
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    Question KMS on Thinkpad W500 + HP ZR22w monitor: no picture with DisplayPort, but DVI works.

    Hi all!

    I recently bought a HP ZR22w IPS monitor to use with my Thinkpad W500 running Arch Linux 64-bit. As it turns out, Kernel Mode Setting (KMS) + DisplayPort (DP) appears to be broken. When KMS+DP is used on boot, I get an error message on the monitor:

    Code:
    Input signal Out of Range
    Change Settings to 1920 x 1080 - 60Hz
    Inside X11, I am unable to get the screen going when KMS+DP is used. xrandr reports the screen being connected and that 1920x1080 is being sent to it. I still have the same error message.

    If I turn off KMS, the monitor works just fine with DP and X11 and xrandr do their jobs.

    If I use a DP->DVI adaptor and instead use the DVI connector on the monitor, KMS works just fine.

    My guess is that the EDID handling is broken somehow on DP. I have tried adding various video= switches in grub to force the resolution but I am not really sure how apply them to the DisplayPort (unable to find any documentation on this) or whether it matters since the problem seems to be that the kernel is unaware it sends an incorrect video signal to the monitor.

    The only reference I have found to this monitor and KMS is this one, but I am not sure what to make of it:
    http://www.spinics.net/lists/dri-devel/msg13061.html

    I would much appreciate any pointers!

    EDIT:

    I booted Fedora 14 with an 2.6.35 kernel and that one works with KMS + DP.
    Last edited by korpenkraxar; 08-16-2011 at 05:00 PM. Reason: Update about Fedora 14

  2. #2
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    Default

    I would suggest trying new kernel (3.0 or newer). If you are still having problems, file a bug (https://bugs.freedesktop.org) and attach your xorg log, xorg config, dmesg output, and xrandr --verbose output.

  3. #3
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    Default

    Quote Originally Posted by agd5f View Post
    I would suggest trying new kernel (3.0 or newer). If you are still having problems, file a bug (https://bugs.freedesktop.org) and attach your xorg log, xorg config, dmesg output, and xrandr --verbose output.
    Thanks. My problems were reported with kernel 3.0.1. Yeah, guess I should file a bug. I wonder how I get to any useful KMS messages though...

  4. #4
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    dmesg output will have any relevant messages. Ideally, you could use git to bisect between the last known good kernel and the first known bad kernel and isolate the problematic commit.

  5. #5
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    Default New monitor, same problem

    In the end I had too much trouble with the anti-glare coating of the HP monitor so I switched to an Eizo EV2333W, which turned out to be better in all respects. Except for the DisplayPort connection, where I still have exactly the same problem with working KMS+DVI but not working KMS+DisplayPort using a recent kernel. I can not see anything useful in the logs.

    This monitor itself however, does provide some useful info.

    Using the old Fedora 2.6.35 kernel and KMS+DisplayPort, the monitor shows this info about the video signal on the Information dialog:

    DisplayPort
    1920x1080
    fH: 76.5kHz
    fV: 59.9Hz

    Using a 3.0 kernel in Arch and KMS+DisplayPort, the monitor shows:

    Signal Error
    DisplayPort
    fD: 111.1MHz
    fH: 50.5kHz
    fV: 44.8Hz

    The "44.8" on the last line is read so there is obviously something wrong with the signal here. I am filing a bug on this.
    Any ideas?

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