Hi and thanks for the explanation.

Because I really need UDMA and I don't know how to properly add this controller
I tried modifying the following bit of code

unknown:
            aprint_normal("unknown VIA ATA controller\n");
            sc->sc_wdcdev.sc_atac.atac_udma_cap = 0;
        }

to set the sc->sc_wdcdev.sc_atac.atac_udma_cap to 5 regardless. But this gave me
DMA errors where the disks were falling back by several UDMA modes.

Any hints? Otherwise, I'll just file a PR.

Thanks again and best regards,

ND