Experiencing FIFO underruns on Intel Skylake platform

[Jani Nikula]

+intel-gfx

On Tue, 19 May 2015, Rainer Koenig <Rainer.Koenig at ts.fujitsu.com> wrote:
> Hi,
>
> I'm testing the vanilla kernel on prototype boards for Intel Skylake.
> The graphics adapter on those boards identifies like this:
>
> 00:02.0 0300: 8086:1912 (rev 04) (prog-if 00 [VGA controller])
> 	Subsystem: 1734:121c
> 	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
> Stepping- SERR- FastB2B- DisINTx+
> 	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
> <MAbort- >SERR- <PERR- INTx-
> 	Latency: 0
> 	Interrupt: pin A routed to IRQ 123
> 	Region 0: Memory at d0000000 (64-bit, non-prefetchable) [size=16M]
> 	Region 2: Memory at c0000000 (64-bit, prefetchable) [size=256M]
> 	Region 4: I/O ports at f000 [size=64]
> 	Expansion ROM at <unassigned> [disabled]
> 	Capabilities: [40] Vendor Specific Information: Len=0c <?>
> 	Capabilities: [70] Express (v2) Root Complex Integrated Endpoint, MSI 00
> 		DevCap:	MaxPayload 128 bytes, PhantFunc 0
> 			ExtTag- RBE+
> 		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
> 			RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
> 			MaxPayload 128 bytes, MaxReadReq 128 bytes
> 		DevSta:	CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
> 		DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, OBFF
> Not Supported
> 		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF
> Disabled
> 	Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
> 		Address: fee00018  Data: 0000
> 	Capabilities: [d0] Power Management version 2
> 		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
> 		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
> 	Capabilities: [100 v1] #1b
> 	Capabilities: [200 v1] Address Translation Service (ATS)
> 		ATSCap:	Invalidate Queue Depth: 00
> 		ATSCtl:	Enable-, Smallest Translation Unit: 00
> 	Capabilities: [300 v1] #13
> 	Kernel driver in use: i915
> 	Kernel modules: i915
>
>
> I'm running both Fedora 21 and OpenSUSE 13.2 on those boards at the
> moment, both with a self compiled Kernel 4.1-rc4 (latest git pull was
> today).
>
> Problem: Whenever power management kicks in and blanks the screen the
> systems behave very strange when trying to get the screen back. The
> screen is not fully restored then, but when I move the mouse (Gnome 3 or
> XFCE desktops) up and down the image rolls up and down like a curtain. I
> see no mouse cursor anymore and can't resume to normal operation.
>
> When this happens I see the following line in dmesg:
>
> [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO
> underrun
>
> Hardware is still the first prototypes for Skylake, BIOS is beta too.
> But I wanted to give a note about that problem here, maybe someone has
> an idea what is missing.

For brand new platforms you should be running drm-intel-nightly branch
from http://cgit.freedesktop.org/drm-intel.

Double check that you have either i915.preliminary_hw_support=1 module
parameter set or CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT=y config option
set.

BR,
Jani.



>
> Regards
> Rainer
> -- 
> Dipl.-Inf. (FH) Rainer Koenig
> Project Manager Linux Clients
> Dept. PDG WPS R&D SW OSE
>
> Fujitsu Technology Solutions
> Bürgermeister-Ullrich-Str. 100
> 86199 Augsburg
> Germany
>
> Telephone: +49-821-804-3321
> Telefax:   +49-821-804-2131
> Mail:      mailto:Rainer.Koenig at ts.fujitsu.com
>
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-- 
Jani Nikula, Intel Open Source Technology Center