I recently installed Linux Mint 18 on my ThinkPad T460p. Having a dual monitor set-up with a internal HiDPI display and a full HD external display connected via Display Port, I tried to adjust the scaling factor of the internal one while leaving the external one untouched.

For that matter, I first ran xrandr -q to check the respective ports, and, subsequently,

xrandr --output eDP-1-1 --auto --output DP-1-2-8 --auto --scale 2x2 --right-of eDP-1-1

As a result, the following error messages were printed:

X Error of failed request:  BadValue (integer parameter out of range for operation)
Major opcode of failed request:  140 (RANDR)
Minor opcode of failed request:  26 (RRSetCrtcTransform)
Value in failed request:  0x40
Serial number of failed request:  47
Current serial number in output stream:  48

The same was printed when running

xrandr --output eDP-1-1 --auto --output DP-1-2-8 --auto --panning 3840x2400+2560+0 --scale 2.0x2.0 --right-of eDP-1-1

To me, these error messages are entirely cryptic. The lack of information on the opcodes makes this a difficult, almost undebugable problem for me. For the commands, I followed the instructions given on ArchWiki.

What intuitively might be of interest to that problem is that instead of running nouveau, I run the proprietary nvidia (nvidia-367, to be precise) drivers to power my GeForce 940MX.

Thanks for your input.

  • If for a moment forget the HiDPI scaling, have you succeed to have both monitors operating, either as mirror or desktop extension....? – George Vasiliou Nov 28 '16 at 23:46
  • Yes, besides the scaling factor everything works fine. I have the external monitor set up as a desktop extension. – foobar Nov 29 '16 at 11:58
  • I never found the method to set different scaling factors for different displays TBH. The graphic driver support is not nearly as good as on Windows, especially for newer NVidia cards. I currently just go along with 1920x1080 on a 15'' screen. The characters are a bit smaller but not that unbearable. Maybe you can consider using some software scaling on your laptop screen instead of through display setting? – xji Nov 29 '16 at 19:40
  • Well, according to the ArchWiki article I linked, setting different scaling factors for different displays should work. However, it is likely that this tutorial was written with noveau (or bumblebee) in mind, an open source alternative to the drivers from nvidia. I am going with your suggestion for now, but hope this problem will be resolved at one point. – foobar Nov 29 '16 at 21:35
  • @foobar Could you try my answer here askubuntu.com/a/867431/26246 (method2 using nvidia-settings) , I think xrandr will work with any scaling function (based on --transform that's includes --scale & --scale-from) . all I can say some nvidia adapters with nvidia proprietary driver version combination don't work even with --scale 1x1 which is the default anyway. – user.dz Jan 5 '17 at 12:24

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