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

[Andrew Vasquez <andrew.vasquez@qlogic.com>]

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).

* 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?

Thanks,
Andrew