Vertical Sync broken on Broadwell

Submitted by Lyude Paul @lyudess

Assigned to Chris Wilson @ickle

Link to original bug (#91366)

Description

Hi! So I've got another bug to report with the Broadwell chipset. Vertical sync seems to be rather broken with Broadwell. I consistently see display tearing around the top of my screen regardless of the conditions. Like the last bug, I've been able to reproduce this with:

• ThinkPad T450s
  
• ThinkPad X1 carbon (latest revision)
  
• Chromebook Pixel
  

All running Fedora 22 and version 2.99.917 of the Intel Xorg driver.