On Wed, Mar 18, 2009 at 09:55:29AM +1100, Michael Ellerman wrote:
> > +4.3.1 pci_enable_msix
> > +
> > +int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
> > +
> > +Calling this function asks the PCI subsystem to allocate 'nvec' MSIs.
> > +The 'entries' argument is a pointer to an array of msix_entry structs
> > +which should be at least 'nvec' entries in size. On success, the
> > +function will return 0 and the device will have been switched into
> > +MSI-X interrupt mode. The 'vector' elements in each entry will have
> > +been filled in with the interrupt number. The driver should then call
> > +request_irq() for each 'vector' that it decides to use.
> > +
> > +If this function returns a negative number, it indicates an error and
> > +the driver should not attempt to allocate any more MSI-X interrupts for
> > +this device. If it returns a positive number, it indicates the maximum
> > +number of interrupt vectors that could have been allocated.
>
> .. that perhaps we should have an example here. eg:
>
> static int foo_driver_enable_msix(struct foo_adapter *adapter, int nvec)
> {
> while (nvec >= FOO_DRIVER_MINIMUM_NVEC) {
> rc = pci_enable_msix(adapter->pdev, adapter->msix_entries, nvec);
> if (rc > 0)
> nvec = rc;
> else
> return rc;
> }
>
> return -ENOSPC;
> }
>
>
> To at least plant the seed in driver writers' minds that they should try
> and support a variable number of MSI-X.
I think that's a great thing to add. It probably doesn't need to delay
these patches going upstream, but if I need to respin the series, I'll
add it. We can always add it later ...
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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