4k laptop eDP display not working on newer laptops
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
HWE Next |
Fix Released
|
Undecided
|
Unassigned | ||
linux (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Trusty |
Fix Released
|
Undecided
|
Robert Hooker |
Bug Description
Impact: Some new laptops with 4k screens are starting to use dp 1.2 only feature of supporting 5.4ghz link rates over displayport which was not turned on until 3.15 even though the plumbing for it was (mostly) there. This should only make more devices work since it has to advertise support for the feature in the dpcd. previously dp 1.2 screens which needed 5.4ghz link rates were forced to use 2.7ghz instead, which would not provide enough bandwidth for some high resolution/high bandwidth screens. It only affects haswell for trusty, broadwell is handled through i915_bdw module which already as this fix and the fix was upstream in 3.15-rc1 so utopic is unaffected.
Fix: Allow the 5.4ghz link rate over displayport.
This has been tested on an affected OEM laptop with a 4K display that requires 5.4ghz link rate to light up (without it the display never turns on) as well as 2 other haswell machines to be sure it doesn't regress.
[ 5.297037] [drm:intel_
[ 5.297038] [drm:intel_
[ 5.297040] [drm:connected_
[ 5.297042] [drm:intel_
[ 5.297045] [drm:intel_
[ 5.297046] [drm:intel_
[ 5.297047] [drm:intel_
Changed in linux (Ubuntu Trusty): | |
status: | New → Fix Committed |
assignee: | nobody → Robert Hooker (sarvatt) |
Changed in linux (Ubuntu): | |
status: | Incomplete → Fix Released |
summary: |
- 4k laptop eDP display not working on a dell precision m3800 + 4k laptop eDP display not working on newer laptops |
Changed in hwe-next: | |
status: | New → Fix Released |
This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:
apport-collect 1369633
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.