Re: [RFC PATCH] PCI: remove access to pci_[enable|disable]_msi() for drivers

[Grant Grundler]

On Tue, Jun 07, 2005 at 09:31:39AM +0200, Arjan van de Ven wrote:
> 
> > > * What if the driver writer does not want MSI enabled for their
> > >   hardware (even though there is an MSI capabilities entry)?  Reasons
> > >   include: overhead involved in initiating the MSI; no support in some
> > >   versions of firmware (QLogic hardware).
> > 
> > Yes, a very good point.  I guess I should keep the pci_enable_msi() and
> > pci_disable_msi() functions exported for this reason.
> > 
> 
> well... only pci_disable_msi() is needed for this ;)

It depends on how the switch from MSI to MSI-X is supposed to work.
I'm thinking of the following sort of sequence:
	pci_disable_msi(dev);
	if (pci_enable_msix(dev,...)) {
		register MSIX stuff
	} else {
		/* MSIX won't work...fall back to MSI */
		pci_enable_msi(dev);
	}

and that makes a bad assumption MSI will work.

grant
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/