Infinite interrupt loop, INTSTAT = 0 in ahd driver?

[Don Bowman]

> From: Justin T. Gibbs [mailto:gibbs at scsiguy.com]
> > In aic79xx.c, in ahd_pause_and_flushwork() there 
> > is a heuristic to prevent looping more than 1000 times.
> > If this happens a message like
> > "Infinite interrupt loop, INTSTAT = 0" is emitted.
> > 
> > I am hitting this case.
> > System has a aic7902. If i set the clock to 20MHz,
> > disable wide negotiation, disable packetisation and 
> > qas, the system will come up. There appears to 
> > be no trouble for the bios to access the drive, it
> > is only the driver that hits this case.
> 
> The BIOS does not operate in packetized mode.  It also only
> sends one trasaction at a time.  This roughly equivalent
> to the behavior you've setup for the driver with your
> settings in SCSI-Select.
> 
> The ahd_pause_and_flushwork() routine is only called from
> timeouts.  While there may be a bug in this routine, it
> is not the root cause of your failure.  What drives are
> you using?  Is the controller operating in PCI or PCI-X
> mode?  Are there any other busmasters on the same PCI(-X)
> segment?  What chipset is on your MB (include revision numbers
> if your system is using the P64H2 PCI-X hub)?
> 

P64H2 is B1 rev [rev 4].
Its e7501 chipset.
its pci-x.
its the only master on the bus.

chip0 at pci0:0:0: class=0x060000 card=0x358015d9 chip=0x254c8086 rev=0x01
hdr=0x00
    vendor   = 'Intel Corporation'
    device   = 'E7501 Host Controller'
    class    = bridge
    subclass = HOST-PCI
none0 at pci0:0:1: class=0xff0000 card=0x358015d9 chip=0x25418086 rev=0x01
hdr=0x00
    vendor   = 'Intel Corporation'
    device   = 'E7500 System Controller (MCH, Hub Interface A) Error
Reporter'
pcib1 at pci0:2:0: class=0x060400 card=0x00000000 chip=0x25438086 rev=0x01
hdr=0x01
    vendor   = 'Intel Corporation'
    device   = 'E7500/E7501 HI_B Virtual PCI-to-PCI Bridge'
    class    = bridge
    subclass = PCI-PCI
none1 at pci0:29:0:        class=0x0c0300 card=0x358015d9 chip=0x24828086
rev=0x02 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82801CA/CAM (ICH3-S/ICH3-M) USB Controller #1'
    class    = serial bus
    subclass = USB
none2 at pci0:29:1:        class=0x0c0300 card=0x358015d9 chip=0x24848086
rev=0x02 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82801CA/CAM (ICH3-S/ICH3-M) USB Controller #2'
    class    = serial bus
    subclass = USB
none3 at pci0:29:2:        class=0x0c0300 card=0x358015d9 chip=0x24878086
rev=0x02 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82801CA/CAM (ICH3-S/ICH3-M) USB Controller #3'
    class    = serial bus
    subclass = USB
pcib4 at pci0:30:0:        class=0x060400 card=0x00000000 chip=0x244e8086
rev=0x42 hdr=0x01
    vendor   = 'Intel Corporation'
    device   = '82801BA/CA/DB (ICH2/3/4) Hub Interface to PCI Bridge (244E)'
    class    = bridge
    subclass = PCI-PCI
isab0 at pci0:31:0:        class=0x060100 card=0x00000000 chip=0x24808086
rev=0x02 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82801CA/CAM (ICH3-S/ICH3-M) LPC Interface'
    class    = bridge
    subclass = PCI-ISA
atapci0 at pci0:31:1:      class=0x01018a card=0x358015d9 chip=0x248b8086
rev=0x02 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82801CA (ICH3) UltraATA/100 EIDE Controller'
    class    = mass storage
    subclass = ATA
ichsmb0 at pci0:31:3:      class=0x0c0500 card=0x358015d9 chip=0x24838086
rev=0x02 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82801CA/CAM (ICH3-S/ICH3-M) SMBus Controller'
    class    = serial bus
    subclass = SMBus
none4 at pci1:28:0:        class=0x080020 card=0x358015d9 chip=0x14618086
rev=0x04 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82870P2 I/OxAPIC Interrupt Controller'
    class    = base peripheral
    subclass = interrupt controller
pcib2 at pci1:29:0:        class=0x060400 card=0x00000050 chip=0x14608086
rev=0x04 hdr=0x01
    vendor   = 'Intel Corporation'
    device   = '82870P2 P64H2 PCI/PCI-X Hub Controller'
    class    = bridge
    subclass = PCI-PCI
none5 at pci1:30:0:        class=0x080020 card=0x358015d9 chip=0x14618086
rev=0x04 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82870P2 I/OxAPIC Interrupt Controller'
    class    = base peripheral
    subclass = interrupt controller
pcib3 at pci1:31:0:        class=0x060400 card=0x00000050 chip=0x14608086
rev=0x04 hdr=0x01
    vendor   = 'Intel Corporation'
    device   = '82870P2 P64H2 PCI/PCI-X Hub Controller'
    class    = bridge
    subclass = PCI-PCI
em0 at pci2:1:0:   class=0x020000 card=0x10118086 chip=0x10108086 rev=0x01
hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82546EB Gigabit Ethernet Controller (copper)'
    class    = network
    subclass = ethernet
em1 at pci2:1:1:   class=0x020000 card=0x10118086 chip=0x10108086 rev=0x01
hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82546EB Gigabit Ethernet Controller (copper)'
    class    = network
    subclass = ethernet
em2 at pci2:3:0:   class=0x020000 card=0x10118086 chip=0x10108086 rev=0x01
hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82546EB Gigabit Ethernet Controller (copper)'
    class    = network
    subclass = ethernet
em3 at pci2:3:1:   class=0x020000 card=0x10118086 chip=0x10108086 rev=0x01
hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82546EB Gigabit Ethernet Controller (copper)'
    class    = network
    subclass = ethernet
ahd0 at pci3:2:0:  class=0x010000 card=0x005f9005 chip=0x801f9005 rev=0x03
hdr=0x00
    vendor   = 'Adaptec'
    device   = 'AIC-7902 Ultra320 SCSI Host Adapter'
    class    = mass storage
    subclass = SCSI
ahd1 at pci3:2:1:  class=0x010000 card=0x005f9005 chip=0x801f9005 rev=0x03
hdr=0x00
    vendor   = 'Adaptec'
    device   = 'AIC-7902 Ultra320 SCSI Host Adapter'
    class    = mass storage
    subclass = SCSI
none6 at pci4:1:0: class=0x030000 card=0x00081002 chip=0x47521002 rev=0x27
hdr=0x00
    vendor   = 'ATI Technologies'
    device   = 'Rage XL PCI'
    class    = display
    subclass = VGA