On Fri, Jun 03, 2005 at 07:16:04PM -0400, Jeff Garzik wrote:
> 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.
Yes, roll that pci_intx() into the core and have it do the
pci_disable_msi() also if needed would be what I am thinking of.
> >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.
Ok, that's fine.
> 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.
Yes, I agree, but let's start with baby steps :)
> 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.
Also agreed.
thanks,
greg k-h
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