sata_down_spd_limit
if (sata_down_spd_limit(link, 0) == 0) {
sata_down_spd_limit(link, 0);
sata_down_spd_limit(slave, 0);
sata_down_spd_limit(failed_link, 0);
sata_down_spd_limit(link, 1);
sata_down_spd_limit(ata_dev_phys_link(dev), 0);
sata_down_spd_limit(link, 0);
int sata_down_spd_limit(struct ata_link *link, u32 spd_limit);