Screen flickering and horizontal black/white lines mixed in with output on
redraw. This only happens when using HDMI output to a single external 1920x1080
monitor and not when using dual monitors or the single laptop screen. If the
screen is static or I move the mouse over a single color background, no
glitching happens. It seems that the more that needs to get redrawn in the
frame, the worse it gets.

I'm not sure how long this has been a problem because I rarely use a single
monitor. I'll report back when mesa 10.1 is released on Arch.

System info from Phoronix Test Suite:
Hardware:
Processor: Intel Core 2 Duo P8400 @ 2.27GHz (2 Cores), Motherboard: Sony VAIO,
Chipset: Intel Mobile 4 MCH + ICH9M, Memory: 3072MB, Disk: 320GB Western
Digital WD3200BEKT-7, Graphics: AMD Mobility Radeon HD 3450/3470 256MB
(680/800MHz), Audio: Realtek ALC262, Monitor: DELL ST2220L, Network: Marvell
88E8055 PCI-E Gigabit + Qualcomm Atheros AR928X Wireless

Software:
OS: Linux, Kernel: 3.13.5-1-ARCH (x86_64), Desktop: Cinnamon 2.0.14, Display
Server: X Server 1.15.0, Display Driver: radeon 7.3.0, OpenGL: 3.1 Mesa 10.0.3
Gallium 0.4, Compiler: GCC 4.8.2 20140206 + Clang 3.4 + LLVM 3.4, File-System:
ext4, Screen Resolution: 1920x1080