Re: [PATCH 7/8] pci: Add CircuitCo VENDOR ID and MinnowBoard DEVICE ID

["H. Peter Anvin" <hpa@zytor.com>]

On 06/26/2013 12:37 PM, Bjorn Helgaas wrote:
> 
> Yeah, that's what I was thinking.
> 
> But Peter's comment makes more sense to me now.  The spec refers to
> that config register as "Subsystem ID," not "Subsystem Device ID," but
> I was confused because most existing usage treats it as a device ID.
> For example, the field in struct pci_device_id is named "subdevice,"
> and all the existing #defines in pci_ids.h are of the form
> PCI_SUBDEVICE_ID_*.
> 
> Device IDs are pretty specific identifiers, so I was thinking that a
> "sub-device ID" would be even more specific.  Then it would make no
> sense to have a "sub-device ID" that was as generic as "MINNOWBOARD."
> But the register is actually *not* a "sub-device ID," and I can see
> that using the same Subsystem ID for all the devices on a board might
> make sense.
> 

Subsystem IDs is basically a board ID in the traditional PC view, but
they didn't call it that because it would have been confusing in other,
nontraditional configurations.

Microsoft has a "best practices" document, which may end up becoming
basis for a future PCI-SIG document clarifying the standard:

http://msdn.microsoft.com/en-us/library/windows/hardware/gg463287.aspx

	-hpa