1 files changed, 17 insertions, 8 deletions

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 03b7a6dd95fe..d67c3fc98f7b 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/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) {
@@ -715,7 +724,7 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
 
                         tf->device |= (block >> 24) & 0xf;
                 }
-        
+
                 qc->nsect = n_block;
                 tf->nsect = n_block & 0xff;
 
@@ -731,23 +740,23 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                 /* The request -may- be too large for CHS addressing. */
                 if ((block >> 28) || (n_block > 256))
                         return 1;
-                        
+
                 /* Convert LBA to CHS */
                 track = (u32)block / dev->sectors;
                 cyl   = track / dev->heads;
                 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. 
                    Cylinder: 0-65535 
                    Head: 0-15
                    Sector: 1-255*/
-                if ((cyl >> 16) || (head >> 4) || (sect >> 8) || (!sect)) 
+                if ((cyl >> 16) || (head >> 4) || (sect >> 8) || (!sect))
                         return 1;
-                
+
                 qc->nsect = n_block;
                 tf->nsect = n_block & 0xff; /* Sector count 0 means 256 sectors */
                 tf->lbal = sect;