monitor connected via Displayport not detected anymore (kernel 5.11 -> 5.12)
Hello,
I have Fedora 33 running, and with the Fedore kernel update from 5.11 series to 5.12 my external monitor is not detected anymore. Same is true with the Fedora supplied 5.13 kernel version.
Hardware in use:
- ThinkPad X1 Yoga 4th / Carbon 7th
- Intel(R) Core(TM) i5-8265U CPU @ 1.60GHz
The Thinkpad is connected to a ThinkPad Thunderbolt 3 Dock with a Thunderbolt cable and a monitor (Eizo EV3285) is connected via Displayport to the docking station.
So I tried with vanilla kernel 5.11 and latest git head from Linus' tree. 5.11 works while latest git head does not. I could bisect that down to kernel commit
ef79d62b5ce5 ("drm/i915: Encapsulate dbuf state handling harder")
With that commit the problem occurs one commit previous to that one the monitor is still detected. I also reported that on mailing list(s) with developers on "To:"