It very much sounds like you have a docking station that requires support for displayport MST (Multi Stream Transport).
That was first available in Linux 3.17 where as the inteldrm code in the tree is currently based on Linux 3.14. On Sun, Sep 25, 2016 at 11:01:20PM +0200, S??awomir Gonet wrote: > Good evening! > > After few tries, I am finally sending bug-maybe-feature report: > > * Software: > - OpenBSD from most recent snapshot (problem exists) > - OpenBSD from most recent snapshot with -current kernel, built with > DEBUGDRM (problem exists) > > * Hardware: > - Dell E7450 > - Dell E-Port Plus Replicator > - 2?? BENQ G2420HD connected to Replicator via DVI-DVI cable > > * Issue: > External monitors, connected to two separate DVI ports on Port > Replicator are cloned (they display exactly the same image) and are > detected by `xrandr' as a single monitor (1920x1080, DP-1). In total, > only two displays are being detected: eDP1 (internal laptop display) and > DP-1 (both DVI-connected displays). > > * Clues?: > On the same machine with Linux 4.8.0-rc7 `xrandr' detects following > displays: > eDP1 (internal) > DP1 (disconnected) > DP1-1 (first DVI display) > DP1-2 (second DPI display) > DP1-3 (disconnected) > DP2 (disconnected) > HDMI1 (disconnected) > HDMI2 (disconnected) > > It seems like OpenBSD has no support/for any other reason is not > detecting those ???nested??? DP's - DP1-1, -2 and -3 and instead showing > "merged" DP1 as connected, with both displays assigned to it. > > * Attachments: > - From OpenBSD-current: > - /var/log/messages > - Xorg.0.log > - output of `xrandr --verbose' > - From Linux 4.8.0-rc7: > - output of `dmesg' > - Xorg.0.log > - output of `xrandr --verbose' > > Sorry for not sending this bug report using sendbug(1) - by the time I > am writing it, it was impossible for me to boot into OpenBSD anytime > soon by multiple reasons. > > Best regards, > Slawek >
