One person claims a similar problem disappeared between v5.14.6 and v5.15.7. Possible fixes are: 9af4bf2171c1 drm/i915/dp: return proper DPRX link training result c8dead5751b8 drm/i915/dp: Use max params for panels < eDP 1.4 Both were backported to the 15.4 kernel in mid/late September.