Comment puis-je entrer ces paramètres HDMI sous Ubuntu 16.04 ?

Les paramètres d'écran suivants fonctionnent dans Ubuntu mate sur un Raspberry Pi 2. Comment puis-je les reproduire dans Ubuntu Desktop 16.04 ? Mon écran est un LG Ultrawide. J'ai fait de nombreuses recherches mais aucune des solutions proposées ne fonctionne pour moi.

    hdmi_ignore_cec_init=1
hdmi_drive=2
disable_overscan=1

hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=87
hdmi_timings=2560 1 64 64 96 1080 1 3 10 31 0 0 1 60 0 185580000 8

config_hdmi_boost=4

max_framebuffer_width=2560
max_framebuffer_height=1280
framebuffer_width=2560
framebuffer_height=1080

gpu_mem=128
arm_freq=900
gpu_freq=275
sdram_freq=500
hdmi_pixel_freq_limit=400000000
avoid_pwm_pll=1

J'ai essayé ce qui suit :

xrandr --newmode "2560x1080_60.00" 230.00 2560 2720 2992 3424 1080 1083 1093 1120 -hsync +vsync

mais quand j'essaie de l'ajouter, j'obtiens :

xxx@cryptoporticus:/usr/share/X11/xorg.conf.d$

xrandr --addmode DVI-I-2 2560x1080_60.00
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  29
  Current serial number in output stream:  30

Sortie xrandr :

xrandr

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 8192 x 8192
DVI-I-0 disconnected (normal left inverted right x axis y axis)
TV-0 disconnected (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
DVI-I-2 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 798mm x 334mm
   1920x1080     60.00*+  59.94    50.00    29.97    60.05    60.00    50.04  
   1680x1050     59.95  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1280x720      60.00    59.94    50.00  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    59.94    59.93  
  2560x1080_60.00 (0x282) 230.000MHz -HSync +VSync
        h: width  2560 start 2720 end 2992 total 3424 skew    0 clock  67.17KHz
        v: height 1080 start 1083 end 1093 total 1120           clock  59.98Hz

sortie get-edid

Section "Monitor"
    Identifier "LG ULTRAWIDE"
    ModelName "LG ULTRAWIDE"
    VendorName "GSM"
    # Monitor Manufactured week 4 of 2014
    # EDID version 1.3
    # Digital Display
    DisplaySize 800 340
    Gamma 2.20
    Option "DPMS" "true"
    Horizsync 30-90
    VertRefresh 56-75
    # Maximum pixel clock is 240MHz
    #Not giving standard mode: 1152x864, 75Hz
    #Not giving standard mode: 1280x1024, 60Hz
    #Not giving standard mode: 1280x720, 60Hz
    #Not giving standard mode: 1600x900, 60Hz
    #Not giving standard mode: 1680x1050, 60Hz

    #Extension block found. Parsing...
    Modeline    "Mode 12" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync 
    Modeline    "Mode 0" 185.58 2560 2624 2688 2784 1080 1083 1093 1111 -hsync -vsync 
    Modeline    "Mode 1" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync 
    Modeline    "Mode 2" 148.500 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
    Modeline    "Mode 3" 74.250 1280 1390 1420 1650 720 725 730 750 +hsync +vsync
    Modeline    "Mode 4" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
    Modeline    "Mode 5" 74.250 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
    Modeline    "Mode 6" 74.250 1920 2448 2492 2640 1080 1082 1089 1125 +hsync +vsync interlace
    Modeline    "Mode 7" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
    Modeline    "Mode 8" 74.250 1920 2008 2052 2200 1080 1082 1087 1125 +hsync +vsync interlace
    Modeline    "Mode 9" 148.500 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync
    Modeline    "Mode 10" 25.200 640 656 752 800 480 490 492 525 -hsync -vsync
    Modeline    "Mode 11" 74.250 1280 1720 1760 1980 720 725 730 750 +hsync +vsync
    Modeline    "Mode 13" 74.25 1920 2008 2052 2200 540 542 547 562 +hsync +vsync interlace
    Modeline    "Mode 14" 74.25 1280 1390 1430 1650 720 725 730 750 +hsync +vsync 
    Modeline    "Mode 15" 27.00 720 736 798 858 480 489 495 525 -hsync -vsync 
    Option "PreferredMode" "Mode 12"
EndSection

sortie get-edid :