I build a kernel based on v5.12-rc4, and cherry-pick below commit, this issue is fixed.
3f3a9bc1f6df drm/i915/ilk-glk: Fix link training on links with LTTPRs And I tried to cherry-pick the other two commits. It's still good. ab03631087f5 drm/i915: Disable LTTPR support when the LTTPR rev < 1.4 7dffbdedb96a drm/i915: Disable LTTPR support when the DPCD rev < 1.4 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1938999 Title: External displays not working on Thinkpad T490 with ThinkPad Thunderbolt 3 Dock To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1938999/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
