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Thread: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

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    Default UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    I've a dual monitor setup with identical 24" 60 Hz WUXGA (1920 x 1200 16:10) LCD monitors.

    I'm thinking of switching one of them for a 28" 60Hz non-gaming UHD (3840 x 2160 16:9) Philips 288p6LJEB monitor. I couldn't find it's response time, but as it is has a TN panel and it's (mostly) for work it shouldn't be an issue, I hope.

    This is a vanilla LEAP 42.3 desktop work box. If necessary it can be upgraded to 15.0, although I'd rather wait for 15.1. Current configuration is:
    - kernel 4.4.155-68-default
    - KDE Frameworks 5.32.0
    - Qt 5.6.2
    - SDDM Display Manager

    Video card is a GTX1050 2GB. It supports UHD in both DisplayPort 1.4 and HDMI 2.0b at 60Hz (and higher), so no issues here.

    From this post https://forums.opensuse.org/showthre...ff-resolutions it seems that I may not be able to set different scales for each monitor. In both system-settings>display and in nvidia-settings I can set different resolutions, but only system-settings has a scale setting (apparently for both displays as one), and none that I could see in nvidia-settings.

    I don't want to reduce the UHD panel resolution, it would defeat the whole purpose of using it.

    Note: the UHD panel turns 90°, but I don't think I'll use portrait mode much.

    My question is: will I have issues with different icon/decorations/text sizes from one screen to another (perhaps mitigated by the 4" difference between screen diagonals) or is there a per-monitor scale setting?

    Thanks,

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Note: the LCD monitors only have DVI-D and VGA ports. both are connected to DVI, one with a DVI-to-HDMI cable.

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    www.usa.philips.com say response time is 5 ms, www.amazon.com say it is just 1 ms...

    Liar, liar, pants on fire.

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Quote Originally Posted by brunomcl View Post
    Liar, liar, pants on fire.
    Actually it is 1ms (Gray to Gray); 5ms typical.

    So not a lie, just misleading.

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Quote Originally Posted by brunomcl View Post
    My question is: will I have issues with different icon/decorations/text sizes from one screen to another (perhaps mitigated by the 4" difference between screen diagonals) or is there a per-monitor scale setting?

    Thanks,
    See here for an idea on how to scale a display in a dual monitor configuration...
    https://wiki.archlinux.org/index.php...ernal_monitors
    openSUSE Leap 15.1; KDE Plasma 5

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Great, this will probably work.

    The monitor should arrive in a couple of weeks, then we'll see.

    Thank you very much, Deano!

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Follow-up:

    Installed new 4K monitor, older 1920x1200 monitor to the right.

    At first run everything too small on 4K (as expected), normal on older monitor.

    To fix 4K, best option to me was change DPI on system-settings from default (~96) to 157. This is the actual dpi, calculated from monitor dimensions and resolution. Usually a divisible-by-eight dpi is used, but in this case 152 and 160 would cause a bit of dithering on narrow letters like "i" and "l".

    I also enabled light hinting and made slight adjustment to fonts size, and set QT_AUTO_SCREEN_SCALE_FACTOR=0 environment variable. I'm not sure what effect this had, if any.

    Then, of course, everything was too big on the older monitor. Fixing this was a bit problematic. After much experimentation, what worked best was to run
    Code:
    xrandr --output DVI-D-0 --scale 1.6x1.6
    soon after KDE starts. There was no need to force (full) composition pipeline in nvidia-settings.

    Weirdly, setting this as an autostart script in system-settings>start & shutdown>autostart didn't work as expected, either set to autostart before or after KDE. This would mess with the desktop settings, repositioning the second monitor on top of the first, and changing the scale setting wrongly at system-settings>screen & monitor>screen. Running it from the desktop after KDE start works as expected.

    Also, a vertical panel on the right of the older monitor would be scaled and re-positioned to the middle of the screen. I ended up removing it.

    I'm having the old recurrent problem of windows extending under the bottom panel on the new monitor, even with it set to always visible. Sometimes it works as it should, but mostly not. It's annoying, and I couldn't find a workaround yet.

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Quote Originally Posted by brunomcl View Post
    Weirdly, setting this as an autostart script in system-settings>start & shutdown>autostart didn't work as expected, either set to autostart before or after KDE. This would mess with the desktop settings, repositioning the second monitor on top of the first, and changing the scale setting wrongly at system-settings>screen & monitor>screen. Running it from the desktop after KDE start works as expected.
    Pure speculation here, but I wonder if disabling the kscreen2 service (via Startup and Shutdown Background Services) might be needed to prevent conflict with any manual configuration?
    openSUSE Leap 15.1; KDE Plasma 5

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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Quote Originally Posted by brunomcl View Post
    Usually a divisible-by-eight dpi is used, but in this case 152 and 160 would cause a bit of dithering on narrow letters like "i" and "l".
    "Usually" by whom or what? Divisible-by-12 is bested only by divisible-by-24, both better than by-8. Maybe your 157 is close enough to by-12=156 to do well enough most of the time with the fonts you use. I often use 143 to avoid the 1.5 HiDPI breakpoint 144 that web browsers use.

    My xrandr startup scripts always go in /etc/X11/xinit/xinitrc.d/ and always work as expected. Maybe that yours didn't is actually a bug, and might be worked around by having xrandr specify both outputs and modes and position and fbmm/dpi along with scale.
    Reg. Linux User #211409 *** multibooting since 1992
    Primary: 42.3,TW,15.0 & 13.1 on Haswell w/ RAID
    Secondary: eComStation (OS/2)&42.3 on 965P/Radeon
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    Default Re: UHD (4K) + WUXGA monitors + nvidia blob + Plasma = mismatched scale issues?

    Quote Originally Posted by mrmazda View Post
    "Usually" by whom or what? Divisible-by-12 is bested only by divisible-by-24, both better than by-8. Maybe your 157 is close enough to by-12=156 to do well enough most of the time with the fonts you use. I often use 143 to avoid the 1.5 HiDPI breakpoint 144 that web browsers use.
    If you click system-settings dpi setting up/down arrows you'll see they change in multiples of 6/8/12/14/24, using a not obvious internal logic, as it depends on the initial dpi value. Initially the changes were 8 by 8, so I assumed it would be that way always, my mistake, thank you for correcting me. Anyway, I tried 156 at the time - as well as many others - and 157 gave the best result. So 157 it is.

    Quote Originally Posted by mrmazda View Post
    My xrandr startup scripts always go in /etc/X11/xinit/xinitrc.d/ and always work as expected. Maybe that yours didn't is actually a bug, and might be worked around by having xrandr specify both outputs and modes and position and fbmm/dpi along with scale.
    TBH I don't really care, the desktop script is just a click away after each (very infrequent) boot. Woks very well for me, although Deanno's suggestion above may be a more efficient solution. I may try it sometime I'm not worried about messing my desktop once again.

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