Bug#885574: problems with USB-C DisplayPort adapters
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
Reply to: