Bug 89177

After updating my fedora linux system to the 3.18 kernel I've been getting PCH fifo underrun errors on boot. Reverting the kernel back to 3.17 resolves the issues.

Setting drm.debug=14 on boot gives 

[jon@localhost]~% dmesg | grep drm
[    1.936241] [drm] Initialized drm 1.1.0 20060810
[    2.193043] [drm] Memory usable by graphics device = 2048M
[    2.193046] [drm] Replacing VGA console driver
[    2.199998] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    2.200000] [drm] Driver supports precise vblank timestamp query.
[    2.287949] [drm] GMBUS [i915 gmbus dpb] timed out, falling back to 
bit banging on pin 5
[    2.297614] fbcon: inteldrmfb (fb0) is primary device
[    2.576664] [drm:cpt_set_fifo_underrun_reporting] *ERROR* uncleared 
pch fifo underrun on pch transcoder A
[    2.576666] [drm:cpt_serr_int_handler] *ERROR* PCH transcoder A FIFO 
underrun

System specs follow

[jon@localhost]~% cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 58
model name	: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
stepping	: 9
microcode	: 0x1b
cpu MHz		: 1251.562
cache size	: 3072 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 2
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm ida arat epb pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt
bugs		:
bogomips	: 4988.60
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:

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[jon@localhost]~% lspci
00:00.0 Host bridge: Intel Corporation 3rd Gen Core processor DRAM Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
00:14.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller (rev 04)
00:16.0 Communication controller: Intel Corporation 7 Series/C210 Series Chipset Family MEI Controller #1 (rev 04)
00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 04)
00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1 (rev c4)
00:1c.1 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2 (rev c4)
00:1c.2 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 3 (rev c4)
00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation QM77 Express Chipset LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 7 Series Chipset Family 6-port SATA Controller [AHCI mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller (rev 04)
02:00.0 System peripheral: Ricoh Co Ltd PCIe SDXC/MMC Host Controller (rev 07)
03:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 [Taylor Peak] (rev 34)