ACPI ATA Driver
ACPI provides a set of BIOS methods that allow an SFF compliant controller to be configured and managed by the OS without specific OS support for the controller.
PIO and DMA modes as selected by the BIOS. BIOS choice of PIO or DMA is respected so the BIOS options should be correctly set.
No mode change down.
On Linux 2.6.24 and 2.6.25 loading pata_acpi before pata_atiixp will cause the ATI IXP interface to be reported as simplex. Fixed in 2.6.26. pata_acpi and ata_generic should be the last PCI ATA drivers to be loaded anyway however.