Chris Wilson is out with yet another Intel X.Org graphics driver update in the xf86-video-intel 2.20.x series.
The xf86-video-intel 2.20.15 update comes days after the 2.20.14 driver that improved old Intel hardware support
, namely for the "Gen4" series. The xf86-video-intel 2.20.14 driver ended up hitting a new bug that dealt with Y-tiling surface preparation for rendering and would result in GPU hangs, so for now that's being disabled. This new driver is also not clobbering the render state after failing to convert the operation to use the blitter and disabling shadow tracking upon server regeneration.
The xf86-video-intel 2.20.15 driver was tagged this morning in Intel Git