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You will need to modify you driver and test on differant ac97 vendors, as they do not all work the same :'( .

do you have hints on how they differ ? or is it just about not having the same vendor/product IDs ?

I wish it was just the vendor/device IDs, but its more to do with which bits you need to change and delays etc, to get a responce, some vendors only need a small delay to get a clear to enter data or get data, others you need to wait for a bit to clear.
Also the offset to info is differant.
Example Vendor: VIA and Vendor: Intel
Need totally differant driver code for there AC97 onboard sound.
The best way to find which are the same is check our the linux drivers and see if they use the same basic driver for the differant vendors.

-> I have changed the INTLN register to 0xA, But it is still firing IRQ 3. Configuration space is always available to us. Isn't it? I read back and it says 0xA.
AC97 pin is internally Or'd to the interrupt controller with the PIRQB# channel.
What is this PRIQB#? What is its significance?