[lkml]   [2009]   [Jan]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: libata, devm_*, and MSI ?
    Mark Lord wrote:
    > Tejun / Jeff,
    > I am working on MSI support for sata_mv, and am trying to puzzle out
    > exactly what the kernel expects for this. Looking at other drivers,
    > both libata and otherwise, yields a variety of conflicting implementations.
    > For starters, the MSI HOW-TO suggests that drivers must be careful
    > to invoke pci_disable_msi() on module unload, but I don't see that
    > happening anywhere in libata.
    > Unless, Tejun, the devm_* routines automatically do this.. do they?
    > Next, there's no mention of a need for invoking pci_intx() in the HOW-TO,
    > yet some device drivers call it, and others do not.
    > Eg. from ahci.c, we have this:
    > if ((hpriv->flags & AHCI_HFLAG_NO_MSI) || pci_enable_msi(pdev))
    > pci_intx(pdev, 1);
    > Which agrees with the existing code in sata_mv:
    > if (msi && pci_enable_msi(pdev))
    > pci_intx(pdev, 1);
    > Which seems to call pci_intx() only when MSI is *not* used. Fine.
    > But then in sata_vsc.c, we do sort of the opposite:
    > if (pci_enable_msi(pdev) == 0)
    > pci_intx(pdev, 0);
    > Either that one is wrong, or pci_intx() is unnecessary in all cases.
    > Again, the MSI HOW-TO doesn't even mention this routine.
    > Looking through the network drivers, it seems that some of them
    > do the pci_intx(pdev,1) call for the cases where pci_enable_msi() fails,
    > similar to ahci.c and sata_mv.c.
    > But not all of them do that.

    Looking through drivers/pci/*, it appears that the call to pci_intx()
    should be totally redundant. pci_enable_msi() does pci_intx(pdev,0)
    on success only, and doesn't touch it otherwise.

    Similarly, pci_disable_msi() does pci_intx(pdev,1).

    So, where does libata cause pci_disable_msi() to be invoked?
    Or is that just missing at the moment?


     \ /
      Last update: 2009-01-20 17:11    [W:0.037 / U:29.956 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site