Hi,
I need to setup a three monitor system on an Intel based touchscreen POS machine using separate X screens so standalone fullscreen apps can be shown on each screen.
Using the Intel driver with two Section "Device" with Driver "intel" and different ZaphodHeads settings work so I can have DISPLAY=:0 and DISPLAY=:0.1 already.
What I can't seem to be able to achieve is using a 3rd Section "Device" that would use the modesetting driver over the udl / udldrmfb kernel driver. Setting
Option "kmsdev" "/dev/dri/card1"
does not help. Also, /dev/fb1 does not appear after udldrmfb is registered during boot. /dev/fb0 for i915 exists.
When Xorg attempts to use both the two device sections with the Intel driver AND the third device section with the modesetting driver to drive the Intel chip and the result is a crash in the server.
When I try with an empty configuration, Xorg picks up all Intel outputs and it also sees the XRandr provider from UDL but no output is activated for it.
The thing is that I need a fixed configuration with pre-set resolutions for all monitors in xorg.conf so I can also pre-calculate the touchscreen transformation matrix in advance. And the reason I need a pre-set touchscreen configuration (as opposed to using xinput map-to-output after X has started) is that as soon as the monitor is turned off and on or the USB connection is replugged, the xinput setup is lost from the X server.
So, how can I convince the modesetting driver to activate the UDL KMS mode from xorg.conf?
I am using kernel 4.18.11 and Xorg 1.19.6.
Thanks in advance, Zoltán Böszörményi