Package: xserver-xorg-core Version: 1.19.2-1+deb9u2 Hardware configuration: Intel HD Graphics 620 (Kabylake GT2)
Sockets on PC: HDMI and USB-C Debian stretch was working fine with the HDMI output and the xserver-xorg-video-intel driver (specified manually in xorg.conf) and default 4.9 kernel I wanted to try attaching to the same monitor using DisplayPort. I tried two devices: - a basic USB-C to DisplayPort adapter cable ("Ibra" brand) - a USB-C hub/dock device with multiple outputs ("TNP" brand, Mini DisplayPort, HDMI, VGA, USB 3, card readers), lsusb mentions USB vendor:device = 05e3:0610 (Genesys Logic) Both of them worked immediately for text mode (BIOS screens and Linux boot process). For X, neither of them worked with the xserver-xorg-video-intel package/driver. I decided to remove that package and try running without any xorg.conf to make it use the modesetting driver. After that change, I found that the "Ibra" adapter would work with X but the hub would not work. Then I tried updating to the latest kernel from backports, 4.13.13-1~bpo9+1 and now the USB-C hub/DisplayPort is working with X too. When it wasn't working, I couldn't find any helpful feedback in the logs. The only thing I noticed sometimes is: (EE) open /dev/fb0: Permission denied