Re: pci_enable_msi() for everyone?

[Greg KH]

On Fri, Jun 03, 2005 at 07:31:12PM -0600, Grant Grundler wrote:
> On Fri, Jun 03, 2005 at 03:45:51PM -0700, 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.
> 
> One complication is some drivers will want to register a different
> IRQ handler depending on if MSI is enabled or not.

That's fine, they can always check the device capabilities and do that.

> If MSI is enabled (and usable), then some MMIO reads can be omitted.
> I've posted a patch for tg3 driver:
> 	ftp://ftp.parisc-linux.org/patches/diff-2.6.10-tg3_MSI-03
> 
> (Just an example! It was not accepted because of buggy HW
>  though it worked great on the HW I have access to.)
> 
> drivers/infiniband/hw/mthca driver is another example.

But it doesn't do that yet either ;)

> > 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.
> > 
> > Or am I missing something pretty obvious here?
> 
> How can the driver know which IRQ handlers to register?

Same as always, use the dev->irq field like they do today.

thanks,

greg k-h
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