ahci_port_signature_detect
ap->ap_type = ahci_port_signature_detect(ap, NULL);
if (ahci_port_signature_detect(ap, NULL) != ap->ap_type) {
int ahci_port_signature_detect(struct ahci_port *ap, struct ata_port *at);
sig = ahci_port_signature_detect(ap, NULL);
at->at_type = ahci_port_signature_detect(ap, at);
if (ahci_port_signature_detect(ap, at) != at->at_type) {