Arch Linux

sgt_b2002

Member

Registered: 2013-11-19

Posts: 7

DisplayPort resolution not detected properly

Hi everyone,

I have a FirePro W4100 with four DP connections. I had one monitor that used an HDMI->DP adapter to connect. Everything worked fine and it detected the native resolution 1920x1080 without issue.

I just got another monitor, identical to the first along with two DP cables to connect them.
I plug in both via the DP cables and I get no screen, and the monitor states there's no signal.

I ssh into the box and export DISPLAY=:0.0 and check xrandr.
After some messing around I finally get to this oddity. If run xrandr -q a few times I get the following:

user@host ~ $ xrandr -q
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
DisplayPort-0 connected (normal left inverted right x axis y axis)
   1024x768      60.00  
   800x600       60.32    56.25  
   848x480       60.00  
   640x480       59.94  
DisplayPort-1 disconnected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-3 disconnected (normal left inverted right x axis y axis)
  1920x1080 (0x5a) 148.500MHz
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock  67.50KHz
        v: height 1080 start 1084 end 1089 total 1125           clock  60.00Hz

user@host ~ $ xrandr -q
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
DisplayPort-0 connected (normal left inverted right x axis y axis)
   1920x1080     60.00 +  50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.88  
   1400x1050     59.95  
   1600x900      59.98  
   1280x1024     60.02  
   1440x900      59.90  
   1280x800      59.91  
   1152x864      59.97  
   1280x720      60.00    50.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       60.00    59.94  
DisplayPort-1 disconnected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-3 disconnected (normal left inverted right x axis y axis)

Most times the result of xrandr -q reflects an incorrect resolution, but once in a while it'll come back with the proper resolutions for the monitor.

Attach the HDMI->DP adapter and all is well again.

I tried setting modeline manually in xorg.conf.d, but this doesn't help.

Section "Monitor"
  Identifier	"DisplayPort-0"
  Modeline	"1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync  
EndSection

Section "Monitor"
  Identifier	"DisplayPort-1"
  Modeline	"1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
EndSection

Assuming the above xorg.conf.d is *not* in place. I can get a screen if I run:

xrandr --output DisplayPort-0 --mode 1024x768

I've also tried the following to no avail...

xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
xrandr --addmode DisplayPort-0 "1920x1080_60.00"

Even after the above, I get the anomalous results from xrandr -q.
This is maddening.

Running 3.17.6-1
xorg-server-1.16.3-1
xf86-video-ati-1:7.5.0-1

If there's anything else I can provide please let me know.
Thanks in advance.