Created attachment 171956 [details] photo of wayland config file for kde plasma, highligting the dpi *** If you're not sure this is actually a bug, instead post about it at https://discuss.kde.org If you're reporting a crash, attach a backtrace with debug symbols; see https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports *** SUMMARY Kde plasma installion on any distro results to this bug where dpi is comically high instead of 96. STEPS TO REPRODUCE 1. install distro 2. install kde and sddm if not already there this is all default OBSERVED RESULT Dpi is set to 294912 Scaling is set to 300% EXPECTED RESULT Dpi set to 96 Scaling is set to 100% SOFTWARE/OS VERSIONS Windows: -- macOS: -- Linux/KDE Plasma: Any linux distro, 6.1.1 (available in About System) KDE Plasma Version: 6.1.1 KDE Frameworks Version: 6.30 Qt Version: 6.7.2 ADDITIONAL INFORMATION large display but 1080p. don't know if that matters.
Does it happen with only that specific screen? Do you have any others you can test with? Can you attach your ~/.config/kwinoutputconfig.json file?
(In reply to Nate Graham from comment #1) > Does it happen with only that specific screen? Do you have any others you > can test with? Can you attach your ~/.config/kwinoutputconfig.json file? "[v0id@localhost ~]$ cat ~/.config/kwinoutputconfig.json [ { "data": [ { "autoRotation": "InTabletMode", "brightness": 1, "colorProfileSource": "sRGB", "connectorName": "HDMI-A-1", "edidHash": "d5a6392353c14421115ec9cd4dde234c", "edidIdentifier": "SAM 1641 1 47 2009 0", "highDynamicRange": false, "iccProfilePath": "", "mode": { "height": 1080, "refreshRate": 60000, "width": 1920 }, "overscan": 0, "rgbRange": "Automatic", "scale": 3, "sdrBrightness": 200, "sdrGamutWideness": 0, "transform": "Normal", "vrrPolicy": "Automatic", "wideColorGamut": false } ], "name": "outputs" }, { "data": [ { "lidClosed": false, "outputs": [ { "enabled": true, "outputIndex": 0, "position": { "x": 0, "y": 0 }, "priority": 0 } ] } ], "name": "setups" } ] [v0id@localhost ~]$ " I don't have any other screens to test, I have 2 other laptops and they work fine. It could be because I have a very large screen that is low resolution, 1080p. Every time I install kde plasma (void linux, kde neon, endeavour os...) on this system with this display, the scaling is set to 300% on default but sometimes It is set to 100% even though the screen is still large, The dpi setting for wayland is always very high on default. I attached the file you requested.
Thanks. What are the physical dimensions of the screen area?
(In reply to Nate Graham from comment #3) > Thanks. What are the physical dimensions of the screen area? I tried to measure, 38,5 cm~ height 73,2cm~ width. Like I said it is 1080p.
Sounds like 32" diagonal, which means 69 DPI. Which means the automatically-calculated scale factor should actually be 75%, not 300%! I see that you found the DPI that GTK calculated was 294912. Which is, um, quite a bit more than 69. If you plug that into our scale calculator, it spits out a scale factor of 307,200%. Which is, um, far too high. So our algorithm notices this and caps it to 300%, the maximum value. The fact that both GTK and Qt get the wrong DPI means that your monitor is reporting the wrong physical size, which causes both toolkits to mis-calculate its DPI, and than that garbage value gets fed into the scale calculator. It appears that the screen is reporting itself as having a 0.2mm diagonal measurement. So now I see why this happens: it doesn't trigger the special code to detect dumb screens that triggers if the width or height is zero; it's cleverly reporting itself as slightly larger than zero, but still not a sane size. I think we can adjust this check to also check for slightly-higher-than-zero dimensions that are nonetheless too small to be usable.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/6180
Git commit f015b73a48576b249bf0a424543d544326ca8b35 by Nate Graham. Committed on 30/07/2024 at 03:16. Pushed by ngraham into branch 'master'. Loosen minimum screen size detection code for output scale calculation We return early for screens with physical height reported as ≤ 0mm. However some extremely dumb screens report a value for their height greater than zero but absurdly small, causing the scale calculator to go ballistic. Theoretically this could happen for widths, too. Let's loosen the detection to flag a physical screen size as invalid if either its width or height is less than 3mm. There is no screen that can possibly make sense to exist at this physical size given the angular resolution of the human eyeball. And if for some reason it does, 100% scale is fine for it. FIXED-IN: 6.2.0 M +3 -2 src/outputconfigurationstore.cpp https://invent.kde.org/plasma/kwin/-/commit/f015b73a48576b249bf0a424543d544326ca8b35