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

[Greg KH <gregkh@suse.de>]

On Mon, Jun 06, 2005 at 06:09:11PM -0700, Andrew Vasquez wrote:
> On Mon, 06 Jun 2005, Greg KH wrote:
> 
> > 
> > Ok, as it seems there is a bit of confusion, here's real code that
> > should help explain what I am proposing.  This works on my desktop, but
> > I don't think it supports MSI :)
> > 
> > I'll go dig out an old 4-way AMD box that has MSI to see if this still
> > works properly, but comments are welcome.
> 
> 
> Thanks for posting some sample code.  Some comments though:
> 
> * 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.

> * A device (notably, our 4gb PCIe fibre-channel products) can support
>   both MSI and MSI-X.  Since the driver has no way of 'disabling' MSI,
>   how would it enable MSI-X?

Agreed, let me respin the patches again, because I think I got the logic
wrong on some of these drivers because of this...

thanks,

greg k-h