[PATCH 5/6] libata: support ATAPI devices

[Albert Lee <albertcc@tw.ibm.com>]

Patch 5/6:
 Support ATA passthru to ATAPI devices.
Revised based on Mark's patch and Jeff's comments.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Cc: Mark Lord <mlord@pobox.com> 
---
After reading Mark's patch, I guess we can safely by-pass the 
cdb_len check: the ATA_12/ATA_16 are for the libata SATL and
get unwrapped to ATA taskfiles before the devices ever see them.

diff -Nrup 04_dev_bit/drivers/ata/libata-scsi.c 05_supp_atapi/drivers/ata/libata-scsi.c
--- 04_dev_bit/drivers/ata/libata-scsi.c	2007-06-07 14:44:27.000000000 +0800
+++ 05_supp_atapi/drivers/ata/libata-scsi.c	2007-06-07 14:44:30.000000000 +0800
@@ -2701,10 +2701,6 @@ static inline ata_xlat_func_t ata_get_xl
 	case VERIFY_16:
 		return ata_scsi_verify_xlat;
 
-	case ATA_12:
-	case ATA_16:
-		return ata_scsi_pass_thru;
-
 	case START_STOP:
 		return ata_scsi_start_stop_xlat;
 	}
@@ -2740,8 +2736,14 @@ static inline int __ata_scsi_queuecmd(st
 				      void (*done)(struct scsi_cmnd *),
 				      struct ata_device *dev)
 {
+	u8 cmd = scmd->cmnd[0];
 	int rc = 0;
 
+	if (unlikely(cmd == ATA_12 || cmd == ATA_16)) {
+		rc = ata_scsi_translate(dev, scmd, done, ata_scsi_pass_thru);
+		return rc;
+	}
+
 	if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len)) {
 		DPRINTK("bad CDB len=%u, max=%u\n",
 			scmd->cmd_len, dev->cdb_len);
@@ -2751,8 +2753,7 @@ static inline int __ata_scsi_queuecmd(st
 	}
 
 	if (dev->class == ATA_DEV_ATA) {
-		ata_xlat_func_t xlat_func = ata_get_xlat_func(dev,
-							      scmd->cmnd[0]);
+		ata_xlat_func_t xlat_func = ata_get_xlat_func(dev, cmd);
 
 		if (xlat_func)
 			rc = ata_scsi_translate(dev, scmd, done, xlat_func);