Greg KH wrote:
> In talking with a few people about the MSI kernel code, they asked why
> we can't just do the pci_enable_msi() call for every pci device in the
> system (at somewhere like pci_enable_device() time or so).  That would
> let all drivers and devices get the MSI functionality without changing
> their code, and probably make the api a whole lot simpler.

Agreed.

And now is a good time to make changes, before bunches of drivers start 
using pci_enable_msi().  I am preparing such a change for the AHCI 
driver (see attached), which will be the standard SATA interface on most 
new motherboards.


> Now I know the e1000 driver would have to specifically disable MSI for
> some of their broken versions, and possibly some other drivers might
> need this, but the downside seems quite small.

tg3 needs to deal with some broken system chipsets as well.  See
tg3_test_msi(), which I would eventually prefer to eliminate in favor of 
PCI quirks and such.

An API note of warning though...   IMO eventually different drivers are 
going to want different behavior from pci_enable_device().  IDE already 
hacks around this, as Alan was required to do a while ago (IDE has a 
weird PCI BAR setup sometimes, requiring care during enabling).

Longer term, I think we will need a

	pci_enable(info on what to enable)

so that drivers can specify ahead of time "don't enable PIO, only MMIO", 
"don't enable MMIO, only PIO", "don't use MSI", etc.  and add a 
pci_disable() to undo all of that.

The more we add singleton functions like pci_enable_msi(), 
pci_set_master(), etc. the more I wish for a single function that 
handled all those details at one atomic point.  There is a lot of 
standard patterns that are hand-coded into every PCI driver's probe 
functions.

	Jeff