Can't adjust monitor gamma on second screen (xinerama)

[Ivan Toman]

Hi!

I use xinerama to drive two monitors on Gentoo, Xorg 7.1 and Matrox
driver mga 4.1. I have two monitors attached to Matrox dualhead 550g,
and everything works ok except I can't change gamma on second (analog
output) monitor (CRT). It needs brighter gamma setting to match LCD (on
DVI output). Putting "gamma" lines in xorg.conf  have not effect, nor
moving sliders for "screen 2" in kgamma (KDE frontend for gamma adjusting).

Setting gamma on first display (LCD) works correctly, and moving sliders
in kgamma also works for it. If I stick option "Synch screens" and then
move sliders, still only "screen 1" is affected. I suspect this is a
bug, because searching at google I found few unanswered questions about
same problem. Can you help me to find solution? I'm even not sure if
this is xorg or mga related...

I attached below contents of my xorg.conf

Thanks a lot,
Ivan



xorg.conf:


Section "ServerLayout"
        Identifier     "Dual"
        Screen 0       "Screen0"
    Screen 1       "Screen1" LeftOf "Screen0"
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
    ModulePath   "/usr/lib/xorg/modules"
    FontPath     "/usr/share/fonts/misc/"
    FontPath     "/usr/share/fonts/TTF/"
    FontPath     "/usr/share/fonts/Type1/"
    FontPath     "/usr/share/fonts/CID/"
    FontPath     "/usr/share/fonts/75dpi/"
    FontPath     "/usr/share/fonts/100dpi/"
EndSection

Section "Module"
    Load  "record"
    Load  "extmod"
    Load  "dbe"
    Load  "dri"
    Load  "glx"
    Load  "xtrap"
    Load  "freetype"
    Load  "type1"
EndSection

Section "InputDevice"
    Identifier  "Keyboard0"
    Driver      "kbd"
EndSection

Section "InputDevice"
    Identifier  "Mouse0"
    Driver      "mouse"
    Option        "Protocol" "auto"
    Option        "Device" "/dev/input/mouse0"
    Option        "ZAxisMapping" "4 5"
EndSection

Section "ServerFlags"
Option "Xinerama" "true"
EndSection

Section "Device"
 Identifier     "Matrox0"
 Driver        "mga"
 BusID        "PCI:3:0:0"
 Screen 0
EndSection

Section "Device"
 Identifier     "Matrox1"
 Driver        "mga"
 BusID        "PCI:3:0:0"
 Screen 1
EndSection

Section "Monitor"
        Identifier      "Monitor0"
    ModelName        "BenQ FP72V"
        HorizSync       31-81
        VertRefresh     56-76
        Option          "DPMS"
  Gamma   0.85  0.85  0.60  # created by KGamma

EndSection

Section "Monitor"
    Identifier   "Monitor1"
    VendorName   "PHL"
    ModelName    "SAMSUNG 959nf"
    HorizSync    30.0 - 110.0
    VertRefresh  50.0 - 160.0
    Option        "DPMS"
    Modeline "1280x1024_95.00"  180.91  1280 1376 1520 1760  1024 1025
1028 1082  -HSync +Vsync
  Gamma   1.40  1.40  1.40  # created by KGamma
EndSection

Section "Screen"
    Identifier "Screen0"
    Device     "Matrox0"
    Monitor    "Monitor0"
    Defaultdepth    24
    SubSection "Display"
        Viewport   0 0
        Depth     24
        Modes    "1280x1024"
    EndSubSection
EndSection

Section "Screen"
        Identifier "Screen1"
        Device     "Matrox1"
        Monitor    "Monitor1"
        Defaultdepth    24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes   "1280x1024"
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     24
        EndSubSection
EndSection