Messages in this thread | | | From | "Colin Coe" <> | Subject | Re: something strange - is it p2x4? | Date | Tue, 21 Apr 1998 21:05:44 +0800 |
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I am no expert, however, I believe that the first PCI device found by the BIOS is *always* IRQ 9, the second PCI device IRQ is dependant on whether IRQ 10 is being used by an ISA or EISA device.
This is from my limited understanding...
CC
-----Original Message----- From: Doug Ledford <dledford@dialnet.net> To: Neal Becker <neal@ctd.comsat.com> Cc: linux-kernel@vger.rutgers.edu <linux-kernel@vger.rutgers.edu> Date: Tuesday, 21 April 1998 20:52 Subject: Re: something strange - is it p2x4?
>Neal Becker wrote: >> >> I have an Intel AL440LX board. I have an AHA2940UW pci card. No >> matter what slot I plug the AHA2940 into, /proc/pci says it's INT9. >> >> The Intel doc on the AL440LX board says that the interrupt line will >> vary with the slot, from INTA - INTD. It says the p2x4 PCI/ISA chip >> will map INTA-INTD to various interrupts. I have NO interrupts >> reserved for ISA. I have NO other PCI cards. I have one AGP video >> card, which also reports it's on INT9 (which is the reason I have a >> problem). >> >> What sets up the mapping of PCI interrupts to INT1-15? I understand >> it's handled by the P2X4 chip. Is this strictly a bios function, or >> does the linux P2X4 driver set this up? >> >> Stranger still, if I stop the boot process when prompted by the >> AHA2940 bios and view the config, it claims it's using INT11. Did >> linux change it when it booted? Is /proc/pci lying? >> >> This is 2.1.96 BTW. > >Actually, from what I can tell so far, this isn't an isolated case. It >appears to be related to the switch over from pcibios_* function usage to >the newer pci_* functions. In the past, we could reliably read the irq >value for the card from the pcibios config space by reading the >PCI_CONFIG_IRQLINE area (I think that's the right mnemonic). Now, in 2.1.96 >and above, we instead get the irq value from the pdev->irq structure value. >If that value isn't right (and it appears to not be right on certain >machines, such as this) then we don't get any interrupts and the system ends >up hanging, or going into a timeout/reset loop. I would guess that the >actual PCI BIOS areas and the PCI CONFIG areas are disagreeing on what the >IRQ is, and that's causing the problem, but I'm not a PCI expert, so I would >defer the actual determination to Martin Mares. Any comments on this >Martin?
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