jhdl
05-17-2016, 08:20 PM
I have a D3100. I'm running Ubuntu Gnome 16.04 (and also Ubuntu Unity) with the latest DisplayLink driver (thanks for that!).
My laptop (Dell XPS 15 9550) has a 4k display (3840x2160).
My two external monitors are also 4K displays (but much larger, of course).
So the resolutions are the same.. but the DPI of the laptop (eDP1) is of course more dense.
If I attach one of my external monitors to the HDMI port of the laptop, the display goes through just fine - I get 4K resolution, and the entire X screen appears on the external monitor.
If I attach one (or both, but to keep it simple I'll discuss attaching just one) of my external monitors to the D3100 attached to the laptop, then I do not get a proper display.
The good news is that I do get a display. However something strange happens with scaling(?) and only a portion of the screen is displayed on the monitor. The monitor appears (and reports) to be in the proper mode (3840x2160), however only about 2/3 of the screen contents are shown on the monitor - and they seem to be stretched/scaled to fill the monitor. In other words all pixels/display area of the monitor is used, but only the central ~70% of the screen is displayed. The remainder of the screen is outside the bounds of the display - I can move the mouse and windows over into that area - it is there (just off of the display). Further, if I take a screenshot, the entirety of the screen (including what is off the monitor) is captured, and it is captured as two 4K screens (my laptop and the external monitor). So the resolution of the screen is all correct, it's just that the 3840x2160 pixels being sent to the monitor are scaled up (or something) by about 130% such that a lot of it doesn't fit on the monitor, and what does appear is large.
NOTE: I also tried this with another laptop running ubuntu 14.04 (kernel 3.16, and running Unity, not Gnome3) which has an HD (1080) display rather than a 4k display - using the D3100 and the same 4K monitor, and I got the same results - plugging the monitor into HDMi port of the laptop everything is fine, plugging the monitor into the D3100 and the very same scaling issue occurs - part of the screen is outside the bounds of what displays on the monitor.
Does anyone have an idea what is happening?
My laptop (Dell XPS 15 9550) has a 4k display (3840x2160).
My two external monitors are also 4K displays (but much larger, of course).
So the resolutions are the same.. but the DPI of the laptop (eDP1) is of course more dense.
If I attach one of my external monitors to the HDMI port of the laptop, the display goes through just fine - I get 4K resolution, and the entire X screen appears on the external monitor.
If I attach one (or both, but to keep it simple I'll discuss attaching just one) of my external monitors to the D3100 attached to the laptop, then I do not get a proper display.
The good news is that I do get a display. However something strange happens with scaling(?) and only a portion of the screen is displayed on the monitor. The monitor appears (and reports) to be in the proper mode (3840x2160), however only about 2/3 of the screen contents are shown on the monitor - and they seem to be stretched/scaled to fill the monitor. In other words all pixels/display area of the monitor is used, but only the central ~70% of the screen is displayed. The remainder of the screen is outside the bounds of the display - I can move the mouse and windows over into that area - it is there (just off of the display). Further, if I take a screenshot, the entirety of the screen (including what is off the monitor) is captured, and it is captured as two 4K screens (my laptop and the external monitor). So the resolution of the screen is all correct, it's just that the 3840x2160 pixels being sent to the monitor are scaled up (or something) by about 130% such that a lot of it doesn't fit on the monitor, and what does appear is large.
NOTE: I also tried this with another laptop running ubuntu 14.04 (kernel 3.16, and running Unity, not Gnome3) which has an HD (1080) display rather than a 4k display - using the D3100 and the same 4K monitor, and I got the same results - plugging the monitor into HDMi port of the laptop everything is fine, plugging the monitor into the D3100 and the very same scaling issue occurs - part of the screen is outside the bounds of what displays on the monitor.
Does anyone have an idea what is happening?