Gentoo's Bugzilla –
Attachment 391962 Details for
Bug 532950Irregular screen blanking in X.Org probably due to DRM errors in i915 driver on Lenovo Thinkpad T440p - WARNING: CPU: 2 PID: 2909 at drivers/gpu/drm/i915/intel_display.c:7256 hsw_enable_pc8+0x465/0x5e0()