diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index a168b52..bb3686a 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -680,7 +680,7 @@
 	 	 * not being called from the SCSI EH.
 	 	 */
 		qc->scsidone = scsi_finish_command;
-		qc->err_mask |= AC_ERR_OTHER;
+		qc->err_mask |= AC_ERR_TIMEOUT;
 		ata_qc_complete(qc);
 	}
 
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 43a2328..f5519f0 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1142,7 +1142,7 @@
 		 * spurious interrupt.  We can live with that.
 		 */
 		if (qc->flags & ATA_QCFLAG_ACTIVE) {
-			qc->err_mask = AC_ERR_OTHER;
+			qc->err_mask = AC_ERR_TIMEOUT;
 			ata_qc_complete(qc);
 			printk(KERN_WARNING "ata%u: qc timeout (cmd 0x%x)\n",
 			       ap->id, command);
@@ -2917,7 +2917,7 @@
 	status = ata_chk_status(ap);
 	if (status & ATA_BUSY) {
 		if (time_after(jiffies, ap->pio_task_timeout)) {
-			qc->err_mask |= AC_ERR_ATA_BUS;
+			qc->err_mask |= AC_ERR_TIMEOUT;
 			ap->hsm_task_state = HSM_ST_TMOUT;
 			return 0;
 		}
@@ -3295,7 +3295,7 @@
 err_out:
 	printk(KERN_INFO "ata%u: dev %u: ATAPI check failed\n",
 	      ap->id, dev->devno);
-	qc->err_mask |= AC_ERR_ATA_BUS;
+	qc->err_mask |= AC_ERR_HSM;
 	ap->hsm_task_state = HSM_ST_ERR;
 }
 
@@ -3353,7 +3353,7 @@
 	} else {
 		/* handle BSY=0, DRQ=0 as error */
 		if ((status & ATA_DRQ) == 0) {
-			qc->err_mask |= AC_ERR_ATA_BUS;
+			qc->err_mask |= AC_ERR_HSM;
 			ap->hsm_task_state = HSM_ST_ERR;
 			return;
 		}
@@ -4159,14 +4159,14 @@
 	/* sleep-wait for BSY to clear */
 	DPRINTK("busy wait\n");
 	if (ata_busy_sleep(ap, ATA_TMOUT_CDB_QUICK, ATA_TMOUT_CDB)) {
-		qc->err_mask |= AC_ERR_ATA_BUS;
+		qc->err_mask |= AC_ERR_TIMEOUT;
 		goto err_out;
 	}
 
 	/* make sure DRQ is set */
 	status = ata_chk_status(ap);
 	if ((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ) {
-		qc->err_mask |= AC_ERR_ATA_BUS;
+		qc->err_mask |= AC_ERR_HSM;
 		goto err_out;
 	}
 
diff --git a/drivers/scsi/sata_mv.c b/drivers/scsi/sata_mv.c
index cd54244..89bcd85 100644
--- a/drivers/scsi/sata_mv.c
+++ b/drivers/scsi/sata_mv.c
@@ -1866,7 +1866,7 @@
 	 	 */
 		spin_lock_irqsave(&ap->host_set->lock, flags);
 		qc->scsidone = scsi_finish_command;
-		qc->err_mask |= AC_ERR_OTHER;
+		qc->err_mask |= AC_ERR_TIMEOUT;
 		ata_qc_complete(qc);
 		spin_unlock_irqrestore(&ap->host_set->lock, flags);
 	}
diff --git a/drivers/scsi/sata_sil24.c b/drivers/scsi/sata_sil24.c
index 9231301..fb59012 100644
--- a/drivers/scsi/sata_sil24.c
+++ b/drivers/scsi/sata_sil24.c
@@ -653,7 +653,7 @@
 	 */
 	printk(KERN_ERR "ata%u: command timeout\n", ap->id);
 	qc->scsidone = scsi_finish_command;
-	qc->err_mask |= AC_ERR_OTHER;
+	qc->err_mask |= AC_ERR_TIMEOUT;
 	ata_qc_complete(qc);
 
 	sil24_reset_controller(ap);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index d58b659..8ff3a7f 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -222,10 +222,15 @@
 };
 
 enum ata_completion_errors {
-	AC_ERR_OTHER		= (1 << 0),
-	AC_ERR_DEV		= (1 << 1),
-	AC_ERR_ATA_BUS		= (1 << 2),
-	AC_ERR_HOST_BUS		= (1 << 3),
+	AC_ERR_DEV		= (1 << 0), /* device reported error */
+	AC_ERR_HSM		= (1 << 1), /* host state machine violation */
+	AC_ERR_TIMEOUT		= (1 << 2), /* timeout */
+	AC_ERR_MEDIA		= (1 << 3), /* media error */
+	AC_ERR_ATA_BUS		= (1 << 4), /* ATA bus error */
+	AC_ERR_HOST_BUS		= (1 << 5), /* host bus error */
+	AC_ERR_SYSTEM		= (1 << 6), /* system error */
+	AC_ERR_INVALID		= (1 << 7), /* invalid argument */
+	AC_ERR_OTHER		= (1 << 8), /* unknown */
 };
 
 /* forward declarations */
@@ -833,7 +838,7 @@
 static inline unsigned int ac_err_mask(u8 status)
 {
 	if (status & ATA_BUSY)
-		return AC_ERR_ATA_BUS;
+		return AC_ERR_HSM;
 	if (status & (ATA_ERR | ATA_DF))
 		return AC_ERR_DEV;
 	return 0;