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Sandy Bridge PCI Card Drivers Fail with "Disabling IRQ"

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  • Sandy Bridge PCI Card Drivers Fail with "Disabling IRQ"

    I wasn't aware of problems with PCI cards on Sandy Bridge (until I bought an Asus P8Z68-V LX) even though there seem to be quite a few reports out there. No fix appears to have been developed (I have tried 3.1-rc10). The only thing to help is booting with irqpoll kernel parameter which seems to reduce the number of occurrences.

    Most reports appear to be about Asus boards, but I did find one about an Intel DH67BL:

    Some other reports, there are some links in them to but of course they are impossible to read at the moment.

  • #2
    Seems to be a more general regression introduced by IRQ code re-factoring in recent kernels:

    One fix already committed for 3.2:

    Is there more needed?:

    Thanks Edward!!!


    • #3
      First fix now in 3.1.3 too and second accepted for 3.2:

      But... although they plus irqpoll reduces the frequency it is still not completely fixed for me.


      • #4
        Looks like suspicion is falling on the ASM1083 PCI Express-to-PCI bridge chip:

        Hopefully this interest means there will be a complete solution.


        • #5
          The Sandy Bridge chipsets don't have PCI support anymore, that's why board vendors use a bridge chip. The ASM1083 is quite a common one but ASMedia doesn't seem to be very Linux-friendly. Usually PCI or PCI Express bridges just work, without needing a driver, but this chip is buggy and probably only tested with Windows.

          I hope motherboard vendors will start to use JMicron chips instead. JMicron supports Linux somehow, as they list the minimal kernel version required for a device to work on their website.


          • #6
            The Intel DH67BL mentioned above uses an ITE IT8892E:

            Not that Intel claims Linux support:

            Gigabyte also appear to use ITE, with the GA-H67A-USB3-B3 manual saying it has an ITE IT8892.

            It would be interesting to hear from anyone that does have PCI working.


            • #7
              That ITE chip is not the PCI bridge. It's the Super I/O chip which means it handles PS/2, parallel, serial, and floppy, and often also hardware monitoring, along with a lot of BIOS stuff. It's not related to PCI at all. You can't even see the Super I/O chip of a motherboard in the lspci output.

              The first link clearly mentions it as a Super I/O chip.


              • #8
                Here's a picture of the ASMedia chip:


                • #9
                  Every link I can find says the ITE IT8892E is the PCI bridge - although I can't find an actual specification.


                  • #10
                    (please remove this post)
                    Last edited by AlbertP; 12-24-2011, 06:30 AM.


                    • #11
                      Including Gigabyte:

                      Anyway, the real point was what is the PCI bridge on the Intel DH67BL? Are there more bridges than the ASMedia causing problems on Linux? Are there any PCI bridges that are working with Linux?


                      • #12
                        A PCI bridge shouldn't even need a driver. They just work, like the ASM1083 did in previous kernels. But the chip is buggy, so you have to copy Windows's behaviour on PCI bridges to get it working, instead of just following the specs.

                        Nearly every chipset has a PCI bridge built-in. I know two exceptions:
                        • Newer Intel chipsets lack PCI so they use a third-party chip.
                        • SiS has an entirely different configuration on their chipsets. The OS talks directly to the PCI devices, through the northbridge, and doesn't know that the southbridge's PCI bridge is in-between. This works fine on Linux, including IRQs.
                        All those PCI bridges in chipsets just work. Intel, AMD, nVidia, all working fine.
                        I'm sorry. Most ITE devices on motherboards are Super I/O chips but they also appear to sell PCI bridges. I had never seen those chips before while ITE I/O chips are quite common, also on motherboards where the PCI is built-in into the chipset.
                        The chip is, however, not listed on ITE's webpage. I couldn't find any official documentation on it.
                        I've removed my previous post.
                        Last edited by AlbertP; 12-24-2011, 06:53 AM.