Newbie question about PCI detection...

[Philip Prindeville]

I was wondering why a lot of drivers go for subsystem vendor ids
and subsystem device ids, rather than just going off the vendor ids
and device ids.  For example, I have an MSI K8MM-V motherboard
(1462:7142), which has onboard graphics using the Via Tech S3
Unichrome Pro chipset (1106:3108).

A quick look at the drivers for this card show that it detects based on
the card id, and not on the chipset.  This is fairly common.

Wouldn't it be simpler to detect first on the card id (since some cards are
quirky), and then detect on the chipset?

What am I missing here?

Thanks,

-Philip