[3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt responses)

[Yinghai Lu]

On Mon, Mar 18, 2013 at 3:05 PM, Jiri Kosina <jkosina at suse.cz> wrote:
> On Mon, 18 Mar 2013, Yinghai Lu wrote:
>
>> > Yes, switching from MSI to IO-APIC-fasteoi makes the report about lost
>> > interrupts go away.
>> >
>> > My understanding from the other mail is that DAniel Vetter already has an
>> > idea what might be going wrong with IRQ acking on GM45 chipsets; hopefully
>> > this datapoint regarding MSI will fit into it.
>>
>> What is /proc/interrupts difference between with and without pci=nomsi ?
>>
>> drm is forced to share irq 16?
>
> Yup, IRQ 16 is being shared, and one of the owners is i915.

the vga report strange INTx status...

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series
Chipset Integrated Graphics Controller (rev 07) (prog-if 00 [VGA
controller])
	Subsystem: Lenovo Device 20e4
	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 44
	Region 0: Memory at f2000000 (64-bit, non-prefetchable) [size=4M]
	Region 2: Memory at d0000000 (64-bit, prefetchable) [size=256M]
	Region 4: I/O ports at 1800 [size=8]
	Expansion ROM at <unassigned> [disabled]
	Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
		Address: fee0100c  Data: 4142
	Capabilities: [d0] Power Management version 3
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Kernel driver in use: i915
	Kernel modules: i915

it should be INTx-, after we have set DisINTx+ in control.

So INTx can not be disabled after it get enabled before ?

the VGA on my T420 looks right.

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation
Core Processor Family Integrated Graphics Controller (rev 09) (prog-if
00 [VGA controller])
	Subsystem: Lenovo Device 21ce
	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-

Thanks

Yinghai