Created attachment 168067 [details] Configure Display Settings, DP-3 failing to detect proper resolutions SUMMARY For a number of months I had 3 identical ViewSonic QHD (2560x1440) displays working almost perfectly on my Neon installation. This was with an AMD Radeon RX 5600 (two screens) and a third screen on the build-in graphics (also AMD) on my Asus ROG STRIX B650E-F w/AMD Ryzen 9 7950X. At this point Neon was up to KDE 5.27. It worked more or less the same in both X11 and Wayland, albeit with small differences and very minor issues. I was very excited about the upcoming 6.0 release of KDE. The 6.0 update actually went pretty well for me, but since then one display or another is now running at 640x480. This will be different displays from time to time. I am unsure which version of KDE was current when this first happened. I have replaced the video card with an AMD Radeon RX 6600, just to have all displays controlled by one device (thinking that might be a complicating factor for plasma. All behavior is the same however. Both Wayland and X11 fail in similar fashion, though X11 can be almost made to work via xrandr. STEPS TO REPRODUCE 1. Boot latest Neon using AMD video and at least 3 HDMI or DP connected displays 2. Configure display settings OBSERVED RESULT Only two of the displays will offer resolution choices above 640x480 (4:3) EXPECTED RESULT All displays should offer appropriate resolutions for the attached displays (in my case, 2560x1440 (16:9) SOFTWARE/OS VERSIONS Operating System: KDE neon 6.0 KDE Plasma Version: 6.0.3 KDE Frameworks Version: 6.0.0 Qt Version: 6.6.3 Kernel Version: 6.5.0-26-generic (64-bit) Graphics Platform: Wayland Processors: 32 × AMD Ryzen 9 7950X 16-Core Processor Memory: 46.7 GiB of RAM Graphics Processor: AMD Radeon RX 6600 Manufacturer: ASUS
I don't know where my detailed text went for this bug.... Short version: For some time I had a working 3-monitor QHD installation, (latest Neon as of last Sept/Oct) and a recent update after 6.0.0 seems to have broken triple monitor installations. I just tested with the Neon live CDs (User Edition, and Testing Edition both) and they do the same thing: one display in 640x480, the others in 2560x1440
(In reply to Jeff Beardsley from comment #1) > I don't know where my detailed text went for this bug.... > > Short version: For some time I had a working 3-monitor QHD installation, > (latest Neon as of last Sept/Oct) and a recent update after 6.0.0 seems to > have broken triple monitor installations. > > I just tested with the Neon live CDs (User Edition, and Testing Edition > both) and they do the same thing: one display in 640x480, the others in > 2560x1440 UPDATE: Just to clarify, the Neo live CDs I tested with were downloaded from neon.kde.org yesterday 4/2/2024
Could you provide the output of kscreen-doctor -o? Thanks!
(In reply to fanzhuyifan from comment #3) > Could you provide the output of kscreen-doctor -o? Thanks! Output: 1 DP-1 enabled connected priority 3 DisplayPort Modes: 0:2560x1440@60*! 1:1920x1440@60 2:2560x1080@60 3:2560x1080@60 4:2560x1080@50 5:2560x1080@30 6:2560x1080@30 7:2560x1080@25 8:2560x1080@24 9:2560x1080@24 10:2048x1152@60 11:1920x1200@60 12:1920x1080@60 13:1920x1080@60 14:1920x1080@60 15:1920x1080@50 16:1920x1080@50 17:1920x1080@30 18:1920x1080@30 19:1920x1080@25 20:1920x1080@24 21:1920x1080@24 22:1600x1200@60 23:1680x1050@60 24:1280x1024@75 25:1280x1024@60 26:1440x900@60 27:1280x800@60 28:1152x864@75 29:1280x720@60 30:1280x720@60 31:1280x720@60 32:1280x720@50 33:1440x576@50 34:1440x576@50 35:1024x768@75 36:1024x768@70 37:1024x768@60 38:1440x480@60 39:1440x480@60 40:1440x480@60 41:1440x480@60 42:832x624@75 43:800x600@75 44:800x600@72 45:800x600@60 46:800x600@56 47:720x576@50 48:720x576@50 49:720x480@60 50:720x480@60 51:720x480@60 52:720x480@60 53:640x480@75 54:640x480@73 55:640x480@67 56:640x480@60 57:640x480@60 58:640x480@60 59:720x400@70 60:1600x1200@60 61:1280x1024@60 62:1024x768@60 63:1920x1200@60 64:1280x800@60 65:1920x1080@60 66:1600x900@60 67:1368x768@60 68:1280x720@60 Geometry: 3627,0 2560x1440 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown HDR: incapable Wide Color Gamut: incapable ICC profile: none Output: 2 DP-2 enabled connected priority 1 DisplayPort Modes: 0:2560x1440@60*! 1:1920x1440@60 2:2560x1080@60 3:2560x1080@60 4:2560x1080@50 5:2560x1080@30 6:2560x1080@30 7:2560x1080@25 8:2560x1080@24 9:2560x1080@24 10:2048x1152@60 11:1920x1200@60 12:1920x1080@60 13:1920x1080@60 14:1920x1080@60 15:1920x1080@50 16:1920x1080@50 17:1920x1080@30 18:1920x1080@30 19:1920x1080@25 20:1920x1080@24 21:1920x1080@24 22:1600x1200@60 23:1680x1050@60 24:1280x1024@75 25:1280x1024@60 26:1440x900@60 27:1280x800@60 28:1152x864@75 29:1280x720@60 30:1280x720@60 31:1280x720@60 32:1280x720@50 33:1440x576@50 34:1440x576@50 35:1024x768@75 36:1024x768@70 37:1024x768@60 38:1440x480@60 39:1440x480@60 40:1440x480@60 41:1440x480@60 42:832x624@75 43:800x600@75 44:800x600@72 45:800x600@60 46:800x600@56 47:720x576@50 48:720x576@50 49:720x480@60 50:720x480@60 51:720x480@60 52:720x480@60 53:640x480@75 54:640x480@73 55:640x480@67 56:640x480@60 57:640x480@60 58:640x480@60 59:720x400@70 60:1600x1200@60 61:1280x1024@60 62:1024x768@60 63:1920x1200@60 64:1280x800@60 65:1920x1080@60 66:1600x900@60 67:1368x768@60 68:1280x720@60 Geometry: 1067,0 2560x1440 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown HDR: incapable Wide Color Gamut: incapable ICC profile: none Output: 3 DP-3 enabled connected priority 2 DisplayPort Modes: 0:640x480@60*! Geometry: 0,0 1067x800 Scale: 0.6 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown HDR: incapable Wide Color Gamut: incapable ICC profile: none
Possible new symptom: One or the other of the working monitors will occasionally blink slowly back and forth between blank and working for a few seconds before settling down to one or the other of those two states. When it ends on blank there is no way to force it to work again short of re-login or reboot.
After truly isolating the problem, I discovered the issue was a flaky cable, as someone on KDEDiscuss suggested.