GDDCcontrol issues with NVIDIA drivers (i2c/monitor/display/DDC) - DP/HDMI failing

my xorg.conf

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 337.25  (buildmeister@swio-display-x64-rhel04-10)  Tue May 27 14:49:08 PDT 2014

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 340.32  (buildmeister@swio-display-x64-rhel04-10)  Tue Aug  5 21:19:39 PDT 2014

Section "ServerLayout"
    Identifier     "Default Layout"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
    ModulePath      "/usr/lib/xorg/modules"
    FontPath        "/usr/share/fonts/X11/misc"
    FontPath        "/usr/share/fonts/X11/cyrillic"
    FontPath        "/usr/share/fonts/X11/100dpi/:unscaled"
    FontPath        "/usr/share/fonts/X11/75dpi/:unscaled"
    FontPath        "/usr/share/fonts/X11/Type1"
    FontPath        "/usr/share/fonts/X11/100dpi"
    FontPath        "/usr/share/fonts/X11/75dpi"
    FontPath        "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
    FontPath        "built-ins"
EndSection

Section "Module"
    Load           "record"
    Load           "extmod"
    Load           "glx"
    Load           "dri2"
    Load           "dbe"
EndSection

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

Section "InputDevice"
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/input/mice"
    Option         "ZAxisMapping" "4 5 6 7"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "LG Electronics LG TV"
    HorizSync       31.0 - 50.0
    VertRefresh     58.0 - 63.0
    Option         "ModeDebug" "TRUE"
    Option         "DPMS" "true"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 210"
    Option         "UseEDIDFreqs" "False"
    Option         "UseEDIDDpi" "False"
    Option         "IgnoreEDID" "True"
    Option         "ModeValidation" "NoVesaModes,NoXServerModes,NoEDIDModes"
    #Option         "RegistryDwords" "EnableBrightnessControl=1"
    Option         "Coolbits" "1"
    Option         "TripleBuffer" "True"
    Option         "RegistryDwords" "PowerMizerEnable=0x1; PerfLevelSrc=0x2222; PowerMizerHardLevel=0x3; PowerMizerHardLevelAC=0x3"
    Option         "ColorSpace" "GPU-0.DFP-0: YCbCr444"
Option "IncludeImplicitMetaModes" "DisplayDevice = DVI-I-1, Scaling=Aspect-Scaled, UseModePool = false"
Option		"RegistryDwords" "RMUseSwI2c=0x01; RMI2cSpeed=100"
EndSection

Section "Screen"

#Option "CustomEDID" "DFP-0:/etc/X11/edid.bin"
#Option "FlatPanelProperties" "Scaling = Native"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1722x968+99+55}"
# Removed Option "metamodes" "1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1920x1080 +0+0 {viewportout=1722x968+99+55}; 1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1920x1080_60i_0 +0+0; 1280x720 +0+0 {viewportout=1082x608+99+55}; 1280x720_50 +0+0"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1722x968+99+55}; 1280x720 +0+0 {viewportout=1266x712+7+3}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1920x1080 +0+0 {viewportout=1722x968+99+55}; 1280x720 +0+0 {viewportout=1082x608+99+55}; 1280x720 +0+0 {viewportout=1266x712+7+3}"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1722x968+99+55}; 1280x720 +0+0 {viewportout=1082x608+99+55}; 1280x720 +0+0 {viewportout=1266x712+7+3}; 1920x1080 +0+0 {viewportout=1722x968+99+55}; 1280x720_50 +0+0 {viewportout=1202x676+39+21}"
# Removed Option "metamodes" "1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1082x608+99+55}; 1280x720 +0+0 {viewportout=1266x712+7+3}; 1280x720_50 +0+0 {viewportout=1202x676+39+21}"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1722x968+99+55}; 1280x720 +0+0; 1280x720 +0+0 {viewportout=1082x608+99+55}; 1280x720 +0+0 {viewportout=1266x712+7+3}; 1280x720_50 +0+0 {viewportout=1202x676+39+21}"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1722x968+99+55}; 1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1082x608+99+55}; 1280x720 +0+0 {viewportout=1266x712+7+3}; 1280x720_50 +0+0 {viewportout=1202x676+39+21}"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1168x657+56+31}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1166x655+57+32}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_60_0 +0+0; 1280x720 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1256x706+12+6}; 1280x720 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "1280x720_50 +0+0; 1280x720 +0+0 {viewportout=1162x653+59+33}; 1280x720 +0+0 {viewportout=1146x644+67+37}; 1280x720 +0+0 {viewportout=1082x608+99+55}"
# Removed Option "metamodes" "DVI-I-1: nvidia-auto-select +0+0"
    #Option         "MonitorLayout" "TDMS"
    #Option         "RegistryDwords" "EnableBrightnessControl=1"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1162x653+59+33}; nvidia-auto-select +0+0"
# Removed Option "metamodes" "1280x720_50 +0+0 {viewportout=1158x651+61+34}; nvidia-auto-select +0+0"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1802x1013+59+33}; 1280x720_50 +0+0 {viewportout=1158x651+61+34}; nvidia-auto-select +0+0"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1722x968+99+55}; 1280x720_50 +0+0 {viewportout=1158x651+61+34}; nvidia-auto-select +0+0"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    30
    Option         "ConnectedMonitor" "DFP-0"
    Option         "UseDisplayDevice" "DFP-0"
    Option         "ExactModeTimingsDVI" "true"
    Option         "FlatPanelProperties" "Dithering = disabled"
    Option         "AllowDDCCI" "1"
# Removed Option "metamodes" "1920x1080_50i +0+0 {viewportout=1776x999+72+40}; 1280x720_50 +0+0"
    Option         "TripleBuffer" "True"
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DFP-0"
    Option         "metamodes" "1280x720_50 +0+0 {viewportout=1150x646+65+36}; nvidia-auto-select +0+0"
    Option         "SLI" "Off"
    Option         "MultiGPU" "Off"
    Option         "BaseMosaic" "off"
    SubSection     "Display"
        Depth       30
    EndSubSection
EndSection

I’m not sure you can have the same option with two different values in xorg.conf.
Try merging those 2 lines:

Option         "RegistryDwords" "PowerMizerEnable=0x1; PerfLevelSrc=0x2222; PowerMizerHardLevel=0x3; Option	       "RegistryDwords" "RMUseSwI2c=0x01; RMI2cSpeed=100"

like this:

Option         "RegistryDwords" "PowerMizerEnable=0x1; PerfLevelSrc=0x2222; PowerMizerHardLevel=0x3; RMUseSwI2c=0x01; RMI2cSpeed=100"

nothing. always the same output . another issue is that the brigthness og LG Plasma ist increasing and decreasing every 20 Seconds . No matter what does it mean .

Gnome and KDE dim the monitor brightness when the machine is idle, and by default gnome starts after 30 seconds, so that part might be easily fixable: http://askubuntu.com/questions/216783/ubuntu-12-10-turn-screen-off-when-inactive-for-never-still-turns-off/388916

Big thnx alexisdm.
i uncckecked idl_dim and reduce idle_brightness from 30 to 10 . It looks better .

Has this issue still not been addressed? I’m having the same issue using a GeForce GTX TITAN X. The solution suggested in this tread also didn’t help.

Edit: I forgot to mention I tested this under Windows and all worked fine (so it’s not a hardware issue).

i2cdetect -l

i2c-0	i2c       	i915 gmbus ssc                  	I2C adapter
i2c-1	i2c       	i915 gmbus vga                  	I2C adapter
i2c-2	i2c       	i915 gmbus panel                	I2C adapter
i2c-3	i2c       	i915 gmbus dpc                  	I2C adapter
i2c-4	i2c       	i915 gmbus dpb                  	I2C adapter
i2c-5	i2c       	i915 gmbus dpd                  	I2C adapter
i2c-6	i2c       	DPDDC-D                         	I2C adapter
i2c-7	i2c       	NVIDIA i2c adapter 0 at 1:00.0  	I2C adapter
i2c-8	i2c       	NVIDIA i2c adapter 1 at 1:00.0  	I2C adapter
i2c-9	i2c       	NVIDIA i2c adapter 2 at 1:00.0  	I2C adapter
i2c-10	i2c       	NVIDIA i2c adapter 6 at 1:00.0  	I2C adapter
i2c-11	i2c       	NVIDIA i2c adapter 7 at 1:00.0  	I2C adapter
i2c-12	i2c       	NVIDIA i2c adapter 8 at 1:00.0  	I2C adapter
i2c-13	i2c       	NVIDIA i2c adapter 9 at 1:00.0  	I2C adapter

for i in $(seq 7 13); do i2cdetect -y $i; done

0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
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30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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70: -- -- -- -- -- -- -- --
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
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30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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00:          -- -- -- -- -- -- -- -- -- -- -- -- --
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30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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70: -- -- -- -- -- -- -- --
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

ddccontrol -p -d -v -v

ddccontrol version 0.4.2
Copyright 2004-2005 Oleg I. Vdovikin (oleg@cs.msu.su)
Copyright 2004-2006 Nicolas Boichat (nicolas@boichat.ch)
This program comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of this program under the terms of the GNU General Public License.

ddcpci initing...
Starting /usr/bin/ddcpci 2 2051184551 &...
Probing for available monitors...
==>Received!
==>Listing...
==>01:00.0 vendor=10de device=17c2 class=0300 irq=46 base0=f6000000 size0=1000000
==>Supported
==>01:00.0-0
==>01:00.0-1
==>01:00.0-2
==>00:02.0 vendor=8086 device=0412 class=0300 irq=32 base0=f7400004 size0=400000
==>EOL
Found PCI device (pci:01:00.0-0)
Found PCI device (pci:01:00.0-1)
Found PCI device (pci:01:00.0-2)
Device: pci:01:00.0-0
==>Received!
==>Opening...
==>01:00.0-0
==>01:00.0 vendor=10de device=17c2 class=0300 irq=46 base0=f6000000 size0=1000000
==>Opened (status=0)...
==>Received!
==>Data, mquery->flags = 0
Error while reading write message answer: Bad message
Reading EDID 0x50 failed.
ddcci_open returned -2
Device: pci:01:00.0-1
==>Received!
==>Opening...
==>01:00.0-1
==>01:00.0 vendor=10de device=17c2 class=0300 irq=46 base0=f6000000 size0=1000000
==>Opened (status=0)...
==>Received!
==>Data, mquery->flags = 0
Error while reading write message answer: Bad message
Reading EDID 0x50 failed.
ddcci_open returned -2
Device: pci:01:00.0-2
==>Received!
==>Opening...
==>01:00.0-2
==>01:00.0 vendor=10de device=17c2 class=0300 irq=46 base0=f6000000 size0=1000000
==>Opened (status=0)...
==>Received!
==>Data, mquery->flags = 0
Error while reading write message answer: Bad message
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-13)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-12)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-11)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-10)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-9)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-8)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-7)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-6)
ioctl(): Connection timed out
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-5)
ioctl(): No such device or address
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-4)
Send: 00                                              | .               
Recv: 00                                              | .               
ioctl(): No such device or address
ioctl returned -1
ioctl(): No such device or address
ioctl returned -1
ioctl(): No such device or address
ioctl returned -1
I/O warning : failed to load external entity "/usr/share/ddccontrol-db/monitor/DELF016.xml"
Document not parsed successfully.
Control brightness has been discarded by the caps string.
Control contrast has been discarded by the caps string.
Control red has been discarded by the caps string.
Control green has been discarded by the caps string.
Control blue has been discarded by the caps string.
Control redblack has been discarded by the caps string.
Control greenblack has been discarded by the caps string.
Control blueblack has been discarded by the caps string.
Control colortemp has been discarded by the caps string.
Control hpos has been discarded by the caps string.
Control vpos has been discarded by the caps string.
Control hsize has been discarded by the caps string.
Control vsize has been discarded by the caps string.
Control auto has been discarded by the caps string.
Control hpincushion has been discarded by the caps string.
Control hpincushionbalance has been discarded by the caps string.
Control vlinearity has been discarded by the caps string.
Control vlinearitybalance has been discarded by the caps string.
Control hmisconvergence has been discarded by the caps string.
Control vmisconvergence has been discarded by the caps string.
Control keybalance has been discarded by the caps string.
Control key has been discarded by the caps string.
Control tdistortionctrl has been discarded by the caps string.
Control tdistortionbalance has been discarded by the caps string.
Control bdistortionctrl has been discarded by the caps string.
Control bdistortionbalance has been discarded by the caps string.
Control tilt has been discarded by the caps string.
Control hmoire has been discarded by the caps string.
Control vmoire has been discarded by the caps string.
Control focus has been discarded by the caps string.
Control coarse has been discarded by the caps string.
Control fine has been discarded by the caps string.
Control defaults has been discarded by the caps string.
Control defaultluma has been discarded by the caps string.
Control defaultgeom has been discarded by the caps string.
Control defaultcolor has been discarded by the caps string.
Control settings has been discarded by the caps string.
Control audiospeakervolume has been discarded by the caps string.
Control degauss has been discarded by the caps string.
Control secdegauss has been discarded by the caps string.
Control osdorientation has been discarded by the caps string.
Control inputsource has been discarded by the caps string.
Control dpms has been discarded by the caps string.
Control power has been discarded by the caps string.
ioctl(): No such device or address
ioctl returned -1
ddcci_open returned -1
Found I2C device (dev:/dev/i2c-3)
ioctl(): No such device or address
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-2)
ioctl(): No such device or address
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-1)
ioctl(): No such device or address
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-0)
ioctl(): No such device or address
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Detected monitors :
 - Device: dev:/dev/i2c-4
   DDC/CI supported: No
   Monitor Name: VESA standard monitor
   Input type: Digital
No monitor supporting DDC/CI available.
If your graphics card need it, please check all the required kernel modules are loaded (i2c-dev, and your framebuffer driver).
ddcpci being released...
==>Received!
==>Quitting...
==>ddcpci is quitting.

nvidia-bug-report.log.gz (267 KB)

No change with v364.19. I really want to grab another Nvidia card but having this broken makes it rather inconvenient for my setup. So I’ll bump just this once in the hope, some developer eyeballs can find their way to this (apparently long standing) issue.
nvidia-bug-report.log.gz (283 KB)

Ditto exact same problem after upgrading from GTX770 to GTX 1060.

Actually for me the problem disappeared after I upgraded from GTX 660 to GTX 1060.

So Xorg.conf hack is no longer required.

Since posting I have found out that the issue (at lease for me) only effects the DisplayPort and works fine over HDMI (again no such issue under Windows).

Really great to know, thanks for the feedback.

alexisdm from this thread knows how to debug i2c. Perhaps you could PM him.

Oh, and he has a stackexchange profile: http://unix.stackexchange.com/users/11825/alexisdm

Same here with a 970 using 381.22-4.

Using GTX 1060 with BenQ XL2730 and NVIDIA-Linux-x86_64-384.47 :

ddcutil and ddccontrol can read the monitor over DVI-D (dual link) but not
DisplayPort or HDMI which is troublesome because I can’t get 144Hz over
DVI-D.

Just tested with NVIDIA-Linux-x86_64-384.59, Same ol’!

Can confirm this does not work with GTX 1080 and Dell P2715Q over DP.

So is it correct that no one has DDC working over display port? GTX1060 running Nvidia driver 384.59 on Ubuntu give me “No monitor supporting DDC/CI available.”

I will add it did the same thing on HDMI. DDC works perfect in Windows.

Since posting I have found out that the issue (at lease for me) only effects the DisplayPort and works fine over HDMI (again no such issue under Windows).

GDDCControl doesn’t work for me with NVIDIA drivers 375.82. My monitor is connected via HDMI:

gddccontrol -v
ddcpci initing...
Starting /usr/bin/ddcpci 1 419563217 &...
Probing for available monitors...
Found PCI device (pci:01:00.0-0)
Found PCI device (pci:01:00.0-1)
Found PCI device (pci:01:00.0-2)
Device: pci:01:00.0-0
Error while reading write message answer: Bad message
Reading EDID 0x50 failed.
ddcci_open returned -2
Device: pci:01:00.0-1
Error while reading write message answer: Bad message
Reading EDID 0x50 failed.
ddcci_open returned -2
Device: pci:01:00.0-2
Error while reading write message answer: Bad message
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-7)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-6)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-5)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-4)
Corrupted EDID at 0x50.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-3)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-2)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-1)
ioctl(): Input/output error
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2
Found I2C device (dev:/dev/i2c-0)
ioctl(): Operation not supported
ioctl returned -1
Reading EDID 0x50 failed.
ddcci_open returned -2

Exact same problem with DisplayPort on GTX1050 running 384.90. DDC/CI works perfectly on Windows.

From what I can gather from googling, DDC/CI over DP seems broken on Linux for this whole generation of cards. Yet there’s no mention of it as a known issue in the driver’s release notes. Is this ever going to be fixed?

Considering this problem’s age I can’t believe it’ll be solved at all.

Using Linux-x86_64 NVIDIA Driver 387.34 Xorg 1.19.5 GeForce GTX 1080 with one DVI display and one DisplayPort display.

In Linux DDC only detects DVI display, no DDC through DisplayPort.
In Windows 10 both displays DDC are detected and work perfectly.

So has to be an issue with the NVIDIA Linux/Xorg driver.

just a heads up, had flaky issues trying to dim/brighten my hp 27es monitor connected via hdmi to a gt710 (ubuntu 16 lts).

found this article and it works much better now after creating the file and rebooting, added the keyboard shortcuts for some pre-selects and I’m in business. Thanks ddcutil and everyone sorting this stuff out.

http://www.ddcutil.com/nvidia/