Lenovo x120e resume regression in 3.15-rc1 bisected to 'drm/crtc-helpers: fix dpms on logic'

I've bisected a resume regression on a Lenovo x120e to 177cf92de4aa97ec1435987e91696ed8b5023130 (drm/crtc-helpers: fix dpms on logic). Everything works fine with this patch reverted on top of 3.15-rc3. I realize it is correcting a coding error that has been in place since 3.11, but it is also causing this laptop to resume to a black screen wherein the platform appears to be locked up (no console, no network). See attached bisect log and lspci. The BIOS version is 1.15.

rtg