libata: minor whitespace, comment, debug message updates

drivers/scsi/libata-scsi.c

@@ -589,7 +589,8 @@ static unsigned int ata_scsi_verify_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
 		head  = track % dev->heads;
 		sect  = (u32)block % dev->sectors + 1;
 
-		DPRINTK("block[%u] track[%u] cyl[%u] head[%u] sect[%u] \n", (u32)block, track, cyl, head, sect);
+		DPRINTK("block %u track %u cyl %u head %u sect %u\n",
+			(u32)block, track, cyl, head, sect);
 		
 		/* Check whether the converted CHS can fit. 
 		   Cylinder: 0-65535 
@@ -665,6 +666,10 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
 		block |= ((u64)scsicmd[3]);
 
 		n_block |= ((u32)scsicmd[4]);
+
+		/* for 6-byte r/w commands, transfer length 0
+		 * means 256 blocks of data, not 0 block.
+		 */
 		if (!n_block)
 			n_block = 256;
 	
@@ -692,7 +697,11 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
 
 	/* Check and compose ATA command */
 	if (!n_block)
-		/* In ATA, sector count 0 means 256 or 65536 sectors, not 0 sectors. */
+		/* For 10-byte and 16-byte SCSI R/W commands, transfer
+		 * length 0 means transfer 0 block of data.
+		 * However, for ATA R/W commands, sector count 0 means
+		 * 256 or 65536 sectors, not 0 sectors as in SCSI.
+		 */
 		return 1;
 
 	if (lba) {
@@ -738,7 +747,7 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
 		head  = track % dev->heads;
 		sect  = (u32)block % dev->sectors + 1;
 
-		DPRINTK("block[%u] track[%u] cyl[%u] head[%u] sect[%u] \n", 
+		DPRINTK("block %u track %u cyl %u head %u sect %u\n",
 			(u32)block, track, cyl, head, sect);
 
 		/* Check whether the converted CHS can fit.