Setting new mode for 2nd monitor fails

[Alex Deucher]

On Fri, Jun 9, 2017 at 5:07 PM, Andrej van der Zee
<andrejvanderzee at gmail.com> wrote:
> Hi Thomas,
>
> Just tried, also does not work. Anyways, I just realized that in Unity on
> Ubuntu I am running 2560x1440 on my 2nd monitor (mac retina 4k screen) but
> all icons are in right size. Somehow it sets the correct dpi I guess.
>
> Just wanted to switch to i3 and all icons are too big on my 2nd monitor. Any
> idea how I can fix I3 to have my second display use the proper icon sizes?
> Probably I am on the wrong mailing list ;-)
>
>
> $ gtf 3840 2160 60
>
>   # 3840x2160 @ 60.00 Hz (GTF) hsync: 134.10 kHz; pclk: 712.34 MHz
>   Modeline "3840x2160_60.00"  712.34  3840 4152 4576 5312  2160 2161 2164
> 2235  -HSync +Vsync

Monitor likely does not support the gtf 3840x2160 modeline, the clock
is way too high.  Try cvt.  It's also possible the monitor does not
support 3840x2160 at all, otherwise it would be exposed already.

Alex

>
> andrej:/var/log$ xrandr --newmode "3840x2160_60.00"  712.34  3840 4152 4576
> 5312  2160 2161 2164 2235  -HSync +Vsync
> andrej:/var/log$  xrandr --addmode DP1  "3840x2160_60.00"
> andrej:/var/log$ xrandr --verbose --output DP1 --mode  "3840x2160_60.00"
> screen 0: 6720x2160 1777x571 mm  96.05dpi
> crtc 1: 3840x2160_60.00  60.00 +2880+0 "DP1"
> xrandr: Configure crtc 1 failed
> crtc 0: disable
> crtc 1: disable
> crtc 2: disable
> crtc 3: disable
> screen 0: revert
> crtc 0: revert
> crtc 1: revert
> crtc 2: revert
> crtc 3: revert
>