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Sviests

Member

From: Riga, Latvia

Registered: 2016-03-24

Posts: 42

Thinkpad E14 + Thinkpad usb-c Gen2 dock + 4k LG 85Hz Monitor issue

I`m looking for help in trying to solve my issue, I can provide logs, configurations that are needed on request as I am not sure which would be more helpful for me to post now.
My issue is the following:
I`ve purchased a Thinkpad USB-C Gen2 dock which has 2x DP outputs and 1x HDMI, the laptop also has 1x separate HDMI output. The laptop itself only has integrated intel graphics and the following CPU: i5-10210U. My issue is that I cannot get the full refresh rate on the monitor through the dock. The monitor has 2x HDMI outputs @50Hz. 1 DP output @85Hz and 1 USB-C (sort of dock) output for video and USB hub. When the monitor is connected to the dock via DP port, max frequency with the laptop screen enabled I can set is 60Hz, otherwise xrandr gives me the following error:

I ~ [1] $ xrandr                                                                                                                                                                 2s 625ms
Screen 0: minimum 8 x 8, current 5360 x 1440, maximum 32767 x 32767
eDP1 connected 1920x1080+3440+0 (normal left inverted right x axis y axis) 310mm x 170mm
   1920x1080     60.02*+  59.93    48.00
   1680x1050     59.88
   1400x1050     59.98
   1600x900      60.00    59.95    59.82
   1280x1024     60.02
   1400x900      59.96    59.88
   1280x960      60.00
   1368x768      60.00    59.88    59.85
   1280x800      59.81    59.91
   1280x720      59.86    60.00    59.74
   1024x768      60.00
   1024x576      60.00    59.90    59.82
   960x540       60.00    59.63    59.82
   800x600       60.32    56.25
   864x486       60.00    59.92    59.57
   640x480       59.94
   720x405       59.51    60.00    58.99
   640x360       59.84    59.32    60.00
DP1 disconnected (normal left inverted right x axis y axis)
DP1-1 disconnected (normal left inverted right x axis y axis)
DP1-2 connected (normal left inverted right x axis y axis)
   1920x1080     60.00 +
   1680x1050     59.95
   1680x945      60.02
   1400x1050     74.87    59.98
   1600x900      60.00
   1280x1024     75.02    60.02
   1440x900      74.98    59.89
   1280x960      60.00
   1366x768      59.79
   1360x768      60.02
   1280x800      74.93    59.81
   1152x864      75.00
   1280x768      74.89    59.87
   1280x720      60.00
   1024x768      75.03    70.07    60.00
   1024x576      59.97
   800x600       72.19    75.00    60.32    56.25
   848x480       60.00
   640x480       75.00    72.81    59.94
   720x400       70.08
DP1-3 connected 3440x1440+0+0 (normal left inverted right x axis y axis) 820mm x 340mm
   3440x1440     84.96    59.97*   49.99
   1920x1080     60.00    60.00    59.94
   1280x720      60.00    59.94
   1024x768      60.00
   800x600       60.32
   720x480       60.00    59.94
   640x480       60.00    59.94
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
I ~ $ xrandr --output DP1-3 --mode 3440x1440 --left-of eDP1
xrandr: Configure crtc 1 failed

I`ve tested this on a different laptop, also with intel HD graphics, but with a slightly older i7 CPU and I get the same issue under linux. On the otherhand, I installed windows on both laptops to update the dock firmware and also do further testing and can report that under windows, I can get the same configuration (4k 85Hz + Laptop screen) to work without issues, but it fails under linux.
Another thing, if I connect my laptop to the monitor directly via its USB-C hub port, 85Hz refresh rate works on the 4k monitor under linux!

I`ve tested this under the following kernels (all current versions):
linux
linux-lts
linux-zen

I`ve also tried this with intel drivers, without intel drivers and using nouveau drivers.

Any help or direction would be greatly appreciated as I`m not sure if this is a dock issue or a linux issue! Thanks in advance!

Last edited by Sviests (2021-01-18 07:35:11)

RagnarOlafsson

Member

Registered: 2021-01-11

Posts: 14

Re: Thinkpad E14 + Thinkpad usb-c Gen2 dock + 4k LG 85Hz Monitor issue

The dock supports only 60Hz through both HDMI and DP.
Read i.e. here.