Cropped Display

Tue Feb 9 21:34:34 UTC 2010

On Tuesday 09 Feb 2010 09:34:17 dael at dael.de wrote:
> 
> Zitat von Mark Greenwood <fatgerman at ntlworld.com>:
> 
> > On Sunday 07 Feb 2010 21:35:24 dael at dael.de wrote:
> >>
> >> Zitat von Mark Greenwood <fatgerman at ntlworld.com>:
> >>
> >> > On Sunday 07 Feb 2010 19:58:07 dael at dael.de wrote:
> >> >>
> >> >> Hello
> >> >>
> >> >> I want to install kubuntu on my media pc and tried the recent live cd.
> >> >> The Desktop started properly but the screen configuration seems to be
> >> >> wrong. Display is a TV with resolution 1360*768 60Hz via HDMI, kubuntu
> >> >> sets the right resolution the refresh rate is 59.8Hz, maybe this is
> >> >> also right?!
> >> >>
> >> >> The problem is that the Desktop seems to be on the wrong position on
> >> >> the screen, the right quarter of the screen is black and on the left
> >> >> side the desktop is cropped.
> >> >>
> >> >> Any Ideas? If possible I want to fix this with the live CD before
> >> >> installiung on hard disk.
> >> >>
> >> >> Thanks
> >> >> Daniel
> >> >>
> >> > What make of graphics card do you have?
> >> >
> >> > Mark
> >>
> >> I have a Intel G45 Express chipset for graphics.
> >>
> >>
> >>
> >>
> > I have also seen this behaviour with a TV and an intel graphics  
> > card. The problem is that most TVs don't return a proper response to  
> > the window manager's resolution queries and it has to make a best  
> > guess. There seem to be some bugs with Intel drivers at the moment.  
> > I know one way to fix it, but it requires a full installation to the  
> > hard disc. It would also help if you could give us the output from  
> > the command lspci
> 
> Well, I want to give a full installation a try if there is a solution.  
> lscpi output is attached.
> 
> Regards
> Daniel
> 

OK, well here we go.

The following is not guaranteed to work but it has worked on the two installations I have tried it on. It requires Linux to be installed to your hard disc.

Note 1 : The following xorg.conf file was generated primarily from an install of Mandriva 2010.0, which seems to do a much better job of configuring this stuff than Ubuntu does. However even that didn't work perfectly until I did the steps involving gtf.

Note 2 : The option 'PreferredMode' in the file below is recorded as 'not used' in the Xorg log. However, for me, it didn't work without it. Your mileage may vary.

The file below is an example xorg.conf file - it needs to be edited and then copied to /etc/X11/xorg.conf.

You will need to know the allowed horizontal sync and vertical refresh rates for your monitor or TV. These go as the parameters 'HorizSync' and 'VertRefresh' as described in the file. These are the crucial values to make this work. They may or may not be specified in the gazillion pages of manual for your TV that your probably threw away when you bought it. I know I did. If you cannot find these values out you have 3 possible courses of action:
1) Guess - the values below might even work.
2) Install Mandriva 2010.0. This will give you an xorg.conf file that might even work. That's where mine came from.
3) Kick the PC and go have a beer instead.

Once you have those you need to generate a ModeLine using the 'gtf' program.
In a terminal, type

gtf 1360 768 60

(The parameters are : Horizontal resolution, vertical resolution, refresh rate)
60Hz refresh should work with any TV. If you're in Europe and plan on using this as a media centre PC, 50Hz is a better choice as it is exactly twice the PAL refresh rate. 100Hz is even better. However many modern TVs won't do a 50Hz or 100Hz refresh and a lot of intel graphics cards won't do 100Hz at this (or indeed any) resolution. Mine doesn't :( Try 60 first. If it works, then get adventurous.

gtf will output a 'ModeLine'. You should paste this into the file where indicated, replacing mine.

Reboot and see what happens. If it doesn't work, check the settings under KDE before you go to option (3).

If you reboot and get a black screen you'll have to switch to another terminal (Ctrl-Alt-F4), log in, delete or rename xorg.conf, and reboot again. If this happens you probably have your Sync or Refresh values wrong.

Good luck....

Mark

# xorg.conf for misbehaving intel drivers with 1360x768 TVs and any flavour of *buntu Karmic
# Thanks to Mandriva 2010.0 for supplying most of this information

Section "ServerFlags"                                
    Option "DontZap" "False" # disable <Ctrl><Alt><BS> (server abort)
    AllowMouseOpenFail # allows the server to start up even if the mouse does not work
EndSection                                                                            

Section "Module"
    Load "dbe" # Double-Buffering Extension
    Load "v4l" # Video for Linux           
    Load "extmod"                          
    Load "glx" # 3D layer                  
    Load "dri" # direct rendering          
EndSection                                 

Section "Monitor"
    Identifier "monitor1"
    VendorName "Generic" 
    ModelName "Flat Panel 1360x768"
   # Get the following two lines of values from your TV datasheet or by guesswork
    HorizSync 31.5-67.0             
    VertRefresh 56.0-65.0           
    Option "PreferredMode" "1360x768"

    # Replace this with your modeline generated by gtf
    Modeline "1360x768_60.00"  84.72  1360 1424 1568 1776  768 769 772 795  -HSync +Vsync  

EndSection

Section "Device"
    Identifier "device1"
    VendorName "Intel Corporation"
    BoardName "Intel 810 and later"
    # Use your driver here, probably 'intel'
    Driver "intel"
    Option "DPMS"
EndSection

Section "Screen"
    Identifier "screen1"
    Device "device1"
    Monitor "monitor1"
    DefaultColorDepth 24

    Subsection "Display"
        Depth 8
        Modes "1360x768"
    EndSubsection

    Subsection "Display"
        Depth 15
        Modes "1360x768"
    EndSubsection

    Subsection "Display"
        Depth 16
        Modes "1360x768"
    EndSubsection

    Subsection "Display"
        Depth 24
        Modes "1360x768"
    EndSubsection
EndSection

Section "ServerLayout"
    Identifier "layout1"
    Screen "screen1"
EndSection

# End xorg.conf

> 