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    SubjectRe: [PATCH 4/25] msi: Simplify msi enable and disable.
    Date
    Rajesh Shah <rajesh.shah@intel.com> writes:

    > On Tue, Jun 20, 2006 at 04:28:17PM -0600, Eric W. Biederman wrote:
    >>
    >> @@ -937,27 +936,8 @@ int pci_enable_msi(struct pci_dev* dev)
    >> if (!pos)
    >> return -EINVAL;
    >>
    >> - if (!msi_lookup_vector(dev, PCI_CAP_ID_MSI)) {
    >> - /* Lookup Sucess */
    >> - unsigned long flags;
    >> + BUG_ON(!msi_lookup_vector(dev, PCI_CAP_ID_MSI));
    >>
    > A driver that calls pci_enable_msi() while MSI is already enabled
    > will hit this BUG_ON. This is different from the behavior of
    > some other pci functions like pci_enable_device(), which
    > silently return success if the requested operation is a nop.
    > It's pretty easy to do the same here too (ditto for MSI-X).

    With MSI-X we can't be a NOOP so it is clearly a bug.

    With MSI it might happen, and I don't have a problem if it becomes
    a noop. At the same time I'm not convinced it isn't a bug.

    All I really care about is that we don't try and do the impossible and
    enable the msi from a half initialized software state like we were doing
    before.

    That was really ugly and impossible to get right.

    Eric
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