ATA_R_AT_HEAD
request->flags = (ATA_R_READ|ATA_R_AT_HEAD|ATA_R_DIRECT|ATA_R_QUIET);
if (request->flags & ATA_R_AT_HEAD) {
request->flags |= (ATA_R_AT_HEAD | ATA_R_REQUEUE);
request->flags |= (ATA_R_AT_HEAD | ATA_R_REQUEUE);
request->flags |= (ATA_R_READ | ATA_R_AT_HEAD | ATA_R_REQUEUE);