[coreboot] r3705 - in trunk/coreboot-v2/src: include/device northbridge/intel/i945 southbridge/intel/i82801gx

Uwe Hermann uwe at hermann-uwe.de
Wed Oct 29 18:26:42 CET 2008

On Wed, Oct 29, 2008 at 05:02:17PM +0100, Peter Stuge wrote:
> svn at coreboot.org wrote:
> >  static const struct pci_driver mc_driver __pci_driver = {
> >  	.ops    = &mc_ops,
> >  	.vendor = PCI_VENDOR_ID_INTEL,
> > -	.device = 0x27a0,
> > +	.device = PCI_DEVICE_ID_INTEL_945_HOST_BRIDGE,
> Sorry, but I don't really agree with these changes.

Yes, we really seems to have a disagreement here. I think the device
names from pci_ids.h make perfect sense, that's why we (and Linux for
that matters) has such a file in the first place, and why we use the
#defines instead of hard-coded PCI device numbers in the code.

> >  static const struct pci_driver i82801gx_ide __pci_driver = {
> >  	.ops	= &ide_ops,
> >  	.vendor	= PCI_VENDOR_ID_INTEL,
> > -	.device	= 0x27df,
> > +	.device	= PCI_DEVICE_ID_INTEL_82801GB_IDE,
> >  };
> My reasoning is that #defines should add information to the code and
> not be an end in itself.

That's exactly my reasoning as well. The number 0x27df is utterly
useless and conveys not information at all. The #define
PCI_DEVICE_ID_INTEL_82801GB_IDE however, where-ever in the code I
stumble upon it, I immediately know that it's an Intel device,
it belongs to the 82801GB chipset/southbridge, and it refers to
the IDE device (not audio, not USB, not anything else).

Yes, if you really want to know the hex number you'll have to look it
up in the pci_ids.h file but that's the case for all other PCI device
numbers we use all over the place (and for all #defines in general).
That shouldn't be a reason to _not_ use them, IMO.

Or, to put it in another way, if we all agree to not use #defines for
PCI IDs (or no #defines at all), we should just drop pci_ids.h (or all
*.h files with #defines in them) entirely. I cannot image we'd want that.

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