Changing 945G GPU IRQ assignment

[Justin Piszcz]

Hi Hugo,

I use a DG965 board currently with built-in video and a 3ware card in the 
x16 slot:

$ cat /proc/interrupts
            CPU0       CPU1       CPU2       CPU3
   0:       3241          0          0          0   IO-APIC-edge      timer
   1:          2          0          0          0   IO-APIC-edge      i8042
   8:          1          0          0          0   IO-APIC-edge      rtc0
   9:          0          0          0          0   IO-APIC-fasteoi   acpi
  12:          3          0          0          0   IO-APIC-edge      i8042
  16:    4383796   12792529    5711773    5079069   IO-APIC-fasteoi   3w-9xxx, uhci_hcd:usb3
  18:      57977      14740          0          0   IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb7
  19:      35308      35028          0          0   IO-APIC-fasteoi   uhci_hcd:usb6
  21:      57951   77630159    3692228   99277364   IO-APIC-fasteoi   uhci_hcd:usb4, eth1
  22:     552076    6937190   17079516   15588018   IO-APIC-fasteoi   HDA Intel, eth2
  23:    3448429   13678957          0          0   IO-APIC-fasteoi   ehci_hcd:usb2, uhci_hcd:usb5
  30:     455701     209453          0          0   PCI-MSI-edge      i915 at pci:0000:00:02.0
  31:     861003    3495076       9393    3194492   PCI-MSI-edge      ahci
  32:    2621566   20858202    5466083   85380656   PCI-MSI-edge      eth0

If you play around with the kernel options, I believe there is an option to
move things around so it goes onto its own IRQ (the graphics card).  I will
see if I can remember what it was, I had the same issue, i915 was on the same
IRQ as the 3ware card I believe.  I do not recall off-hand which option it was.
Will take a look and report back if I find anything.

Justin.


On Wed, 30 Sep 2009, Jacques, Hugo wrote:

> Hi,
>
> I have an Intel 945G-based system on which I installed a custom board (qhal_host below) into the PCIe x16 slot.
>
> I am running Linux 2.6.29.6, Xorg 1.6.0 and xf86-video-intel 2.7.0.
>
> Is there a way to have the Integrated Graphics Controller (i915 at pci:0000:00:02.0 below) being assigned to an IRQ different than 16?
>
> I am asking this because I want to debug an interrupt issue. At some point I get ~100000 interrupts a second on IRQ16 despite neither the qhal_host or the Intel GPU devices report the interrupt is theirs (through respective IIR registers).
>
> Anybody heard of 945G issues when both the GPU and a card in the PCIe x16 slot are generating interrupts as the same time?
>
> Thanks in advance.
>
> cat /proc/interrupts
>           CPU0       CPU1
>  0:         71          0   IO-APIC-edge      timer
>  1:          2          0   IO-APIC-edge      i8042
>  2:          0          0    XT-PIC-XT        cascade
>  4:         10          0   IO-APIC-edge
>  9:          0          0    XT-PIC-XT        acpi
> 14:       7882          0   IO-APIC-edge      ide0
> 16:       8586          0   IO-APIC-fasteoi   qhal_host,i915 at pci:0000:00:02.0
> 28:       5872          0   PCI-MSI-edge      eth0
> 30:          0          0   PCI-MSI-edge      ahci
> NMI:          0          0   Non-maskable interrupts
> LOC:    2170197    2053944   Local timer interrupts
> RES:        754        957   Rescheduling interrupts
> CAL:         35         22   Function call interrupts
> TLB:        409        421   TLB shootdowns
> TRM:          0          0   Thermal event interrupts
> SPU:          0          0   Spurious interrupts
> ERR:          0
> MIS:          0
>
>
>
>
>  
> Hugo Jacques, ing.
> Video Tech Leader
> Video Intelligence Solutions
> Verint Systems Inc.
>
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