I'm using Manjaro KDE, and having some serious problems with connecting my external monitor, that appeared out of the blue.
I have a Dell 27" S2716DG monitor that I connect to my Yoga laptop via a Lenovo USBC adapter. For months it's worked well, with no major issues (Monitor is 1440P and laptop is 4K, when I unplug manjaro automatically sets the laptop display resolution back to 4K instead of the lowered 1440P, and i have to change it. This automatic change is minor, but annoying (if anyone knows a fix.))
About a week ago, with no memorable update or change to cause the behaviour, I noticed when I plugged in my external monitor via HDMI via the adapter, as i always do, the resolution of the monitor would be something like 720p or lower. I don't remember the exact resolution. I thought "weird, maybe it's the same bug causing the laptop display to go to 4K, but other way around. But if i went into my display settings, the settings did not give me a higher resolution than the grainy 720P or whatever-it-was resolution it was set at. In other words, Manjaro could not detect that mt 1440P external monitor was more than the ~720p resolution it was wrongly set as. No higher resolutions were shown in the display manager. But if i tinkered with my display options to use only the monitor and not both the monitor and internal display, then the resolution of the monitor was detected at 1440P. But not always, it was very finicky and strange, and very frustrating because it was repeatable but no clear set of steps fixed it other than unplugging and re plugging and changing and restarting again and again until something clicked.
That seems to have stopped, but a worse bug manifested, which i think is somehow related. Now, when I restart my laptop (nothing connected), it starts fine. But the moment i connect my external monitor, the laptop display starts intermittently flickering in a unresponsive manner (video linked below), while the display seems to have been connected. But no input via mouse or track pad moves anything on the monitor. It may as well be a still image as no button pressing or mouse clicking does anything, all the while my laptop display is flickering dangerously. I try every combination of buttons, everything from button mashing to alt-tabbing to the display-monitor switch user key to swap which monitor shows and doesn't.
Using ctrl-alt-f2, the terminal emulator works seems to pop up, but the flickering continues, and letters do not show when i press them on the emulator. I can switch back and fourth with crtl-alt-f1 and ctrl-alt-f2, but that's it, no input in either works. Even unplugging the monitor at this stage leaves the internal display black until restart. I've tried multiple HDMI cables and there's no variation between them, they all reproduce it. I don't have another USBC hub, but considering this one is a couple months old and from the same manufacturer as the laptop (and not dropped/damaged in the recent past), I don't think the issue is with the adapter, and currently cannot test another. I have not tried with a different monitor yet, but can ask a roommate later to test that.
The first video link is a quick one showing the display glitching out.
The second video is a longer one showing me struggling to get any input to the system. Somehow I was able to get it to show the display after button mashing, but that was a one-off fluke I have not been able to reproduce. Every other attempt forces me to restart the machine. At the end of the video I somehow got lucky and something clicked in the machine, but now i'm struggling to get the monitor showing and have a responsive machine every time I plug in the HDMI since my restart, as expected.
The display does not start to glitch out when the hub or the power is connected, only when a HDMI cable is plugged in. I had to restart today after it working (plugged in and left untouched) for 2 days, and now I can't connect the monitor again at all. When it does choose to work, there seems to be 0 issue at all, and so long as it's not unplugged, I wouldn't even notice there's a problem. Sometimes on hibernation it seems to act up again, but if the machine is just locked, it seems to handle that fine.
Before, there was no issue turning on with the HDDMI plugged in, i saw grub, and everything "just worked". Now i see Grub, and then the Lenovo logo, and before i even hit the lock screen the screen is black and unresponsive.
I have no idea what changed to cause this behaviour to start.
I have a eGPU which seems to work on the display port when connected, but I've been having issues as when I plug it in, i get logged out of my environment, and when i log in it seems to be a fresh one and I lose everything. Also there's some manjor screen tearing that makes the external monitor almost unusable. Also I can't tell if the eGPU is actually holding weight, as i can't play any basic games without horrible lag. Currently i boot to windows to play games as Insurgency can play on ultra at 100 fps on Windows, but won't even boot on linux. Other games play at 10% the Windows fps. I can't tell if only the dedicated graphics are being used, and the screen tearing makes none of it worth it, which is why I'm working/programming with HDMI, but now that's broken too.
I would really appreciate any help to fix this. As is, unless I somehow get lucky and never turn off or unplug or move my laptop, my monitor is unused now. I've tried ~10 times this morning and cannot get it to work though.
System: Host: yoga Kernel: 5.6.11-1-MANJARO x86_64 bits: 64 compiler: gcc v: 9.3.0 Desktop: KDE Plasma 5.18.5 tk: Qt 5.14.2 wm: kwin_x11 dm: SDDM Distro: Manjaro Linux Machine: Type: Convertible System: LENOVO product: 81C4 v: Lenovo YOGA C930-13IKB serial: <filter> Chassis: type: 31 v: Lenovo YOGA C930-13IKB serial: <filter> Mobo: LENOVO model: LNVNB161216 v: SDK0R32862 WIN serial: <filter> UEFI: LENOVO v: 8GCN30WW date: 07/13/2018 Battery: ID-1: BAT1 charge: 54.9 Wh condition: 54.9/60.0 Wh (91%) volts: 8.3/7.7 model: Celxpert BASE-BAT type: Li-poly serial: <filter> status: Discharging CPU: Topology: Quad Core model: Intel Core i7-8550U bits: 64 type: MT MCP arch: Kaby Lake rev: A L2 cache: 8192 KiB flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 32012 Speed: 800 MHz min/max: 400/4000 MHz Core speeds (MHz): 1: 800 2: 800 3: 802 4: 800 5: 800 6: 800 7: 800 8: 800 Graphics: Device-1: Intel UHD Graphics 620 vendor: Lenovo driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:5917 Display: x11 server: X.Org 1.20.8 driver: intel compositor: kwin_x11 resolution: 2560x1440~60Hz OpenGL: renderer: Mesa Intel UHD Graphics 620 (KBL GT2) v: 4.6 Mesa 20.0.6 direct render: Yes Audio: Device-1: Intel Sunrise Point-LP HD Audio vendor: Lenovo driver: snd_hda_intel v: kernel bus ID: 00:1f.3 chip ID: 8086:9d71 Sound Server: ALSA v: k5.6.11-1-MANJARO Network: Device-1: Intel Wireless-AC 9260 driver: iwlwifi v: kernel port: 3040 bus ID: 6b:00.0 chip ID: 8086:2526 IF: wlp107s0 state: up mac: <filter> Drives: Local Storage: total: 953.87 GiB used: 210.52 GiB (22.1%) ID-1: /dev/nvme0n1 vendor: Samsung model: MZVLB1T0HALR-000L2 size: 953.87 GiB speed: 31.6 Gb/s lanes: 4 serial: <filter> rev: 4L1QEXA7 scheme: GPT Partition: ID-1: / size: 510.87 GiB used: 210.49 GiB (41.2%) fs: ext4 dev: /dev/nvme0n1p5 Sensors: System Temperatures: cpu: 35.5 C mobo: 29.8 C Fan Speeds (RPM): N/A Info: Processes: 272 Uptime: 3m Memory: 15.39 GiB used: 1.93 GiB (12.6%) Init: systemd v: 245 Compilers: gcc: 9.3.0 Shell: zsh v: 5.8 running in: konsole inxi: 3.0.37
Sorry for the potato quality, I clearly can't use any screen recorder to show this behaviour.