On Mon, Jun 06, 2005 at 08:00:26AM +1000, Benjamin Herrenschmidt wrote:
>
> > Hm, here's a possible function to do it (typed into my email client, not
> > compiled, no warranties, etc...):
> >
> > /* returns 1 if device is in MSI mode, 0 otherwise */
> > int pci_in_msi_mode(struct pci_dev *dev)
> > {
> > int pos;
> > u16 control;
> >
> > pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
> > if (!pos)
> > return 0;
> > pci_read_config_word(dev, msi_control_reg(pos), &control);
> > if (control & PCI_MSI_FLAGS_ENABLE);
> > return 1;
> > return 0;
> > }
>
> That would assume the architecture/slot/hw_setup always support MSI.
> What if you put an SMI capable card in a machine that doesn't do MSI ?
The ENABLE flag would not have been set by the current pci_enable_msi()
function.
> > If you use the above function, then you can tell the difference and
> > register different irq handlers if you wish.
>
> No you can't because you lack the result code from pci_enable_msi()
> which can fail (because it's veto'd by the arch for example)
That's what the above function is for. To call before setting up the
irq handlers.
> > The main point being is that the pci_enable_msi() function would not
> > have to be explicitly called by your driver, it would have already been
> > taken care of earlier by the PCI core. That's what I want to do and am
> > wondering if there would be any bad side affects to it.
>
> Disagreed.
Disagreed in what way? What's the bad side affects?
thanks,
greg k-h
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