Hello,
I am having an issue where the pixel clock of my UHD display is being limited to 165.0 MHz apparently, and I therefore cannot configure the display to it’s native resolution.
I am using nVidia Quadro P400 GPU with driver 381.22 on Ubuntu 16.04. The display is an LG Ultrawide with only HDMI inputs, so I am using an UHD-compatible active DisplayPort to HDMI adapter (Icybox IB-AC506; as far as I can tell DP v1.2 capable).
This is apparent in the logs (/var/log/Xorg.0.log):
[ 285.832] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-5): connected
[ 285.833] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-5): Internal TMDS
[ 285.833] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-5): 165.0 MHz maximum pixel clock
This is apparent when saving the EDID with nvidia-settings and using parse-edid:
Identifier "LG ULTRAWIDE"
ModelName "LG ULTRAWIDE"
VendorName "GSM"
# Monitor Manufactured week 12 of 2016
# EDID version 1.3
# Digital Display
DisplaySize 670 280
Gamma 2.20
Option "DPMS" "true"
Horizsync 30-90
VertRefresh 56-75
# Maximum pixel clock is 240MHz
Why is this so? Is this a software bug? Hardware problem? Is the cable to blame? The adapter?
How do I diagnose this issue?
Any help is much appreciated.
LP,
Jure
nvidia-bug-report.log.gz (144 KB)
Please add
Option "ModeDebug" "true"
to the Screen section of your xorg.conf. Then run nvidia-bug-report.sh and attach output file to your post.
Attached. Sorry for the delay.
The UHD display is at DP-5, DP-3 is a second display with a lower resolution.
LP,
Jure
nvidia-bug-report.log.gz (144 KB)
This line indicates that this is a passive adapter, not an active one:
[ 50.381] (--) NVIDIA(GPU-0): LG Electronics LG ULTRAWIDE (DFP-5): Internal TMDS
If it were an active adapter, it would say DisplayPort instead of TMDS. DP-4 (also known as DFP-4) is the DisplayPort partner half of that connector:
DP-4 disconnected (normal left inverted right x axis y axis)
Identifier: 0x232
Timestamp: 68779
Subpixel: unknown
Clones:
CRTCs: 0 1 2 3
Transform: 1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
<b>SignalFormat: DisplayPort</b>
supported: DisplayPort
ConnectorType: DisplayPort
<b>ConnectorNumber: 2</b>
_ConnectorLocation: 2
DP-5 connected 1920x1080+1680+0 (0x234) normal (normal left inverted right x axis y axis) 673mm x 284mm
Identifier: 0x233
Timestamp: 68779
Subpixel: unknown
Gamma: 1.0:1.0:1.0
Brightness: 1.0
Clones:
CRTC: 1
CRTCs: 0 1 2 3
Transform: 1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
CscMatrix: 65536 0 0 0 0 65536 0 0 0 0 65536 0
EDID:
00ffffffffffff001e6df159eb7e0100
0c1a010380431c78eaca95a6554ea126
0f5054a54b80714f818081c0a9c0b300
0101010101017e4800e0a0381f404040
3a00a11c21000018023a801871382d40
582c4500a11c2100001e000000fc004c
4720554c545241574944450a000000fd
00384b1e5a18000a2020202020200125
02031cf1499004031412051f01132309
07078301000065030c001000023a8018
71382d40582c450056512100001e011d
8018711c1620582c250056512100009e
011d007251d01e206e28550056512100
001e8c0ad08a20e02d10103e96005651
21000018000000ff003631324e544641
32573032370a000000000000000000af
BorderDimensions: 4
supported: 4
Border: 0 0 0 0
range: (0, 65535)
<b>SignalFormat: TMDS</b>
supported: TMDS
ConnectorType: DisplayPort
<b>ConnectorNumber: 2</b>
_ConnectorLocation: 2
1920x1080 (0x234) 148.500MHz +HSync +VSync *current +preferred
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
Given that the adapter I have (Icybox IB-AC506) is advertised as active, how do I recognize an actual active adapter pre-purchase?
LP,
Jure
I’m not sure you can just from looking at it. The only foolproof way I know of is to plug it in and check Xorg.0.log or xrandr --verbose.
Looking at the specs of your adapter, it says 4k@30Hz. Which is not what I would expect from an active HDMI 2.0 adapter. Should be 4k@60Hz then.
I never thanked you guys. That was it.
My issue was that the reseller I was using neglected to include the @30Hz bit in their product specification and the result was confusion.
I’ve alerted them to the issue and brought a different adapter that can do UHD @60Hz and it works flawlessly.
LP,
Jure
Which did you buy that worked?