2 files changed, 17 insertions, 5 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index f70431a4c9e9..8a66ca5f9530 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2551,10 +2551,6 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
         if (tf->protocol == ATA_PROT_DMA && dev->dma_mode == 0)
                 goto invalid_fld;
 
-        if (cdb[1] & 0xe0)
-                /* PIO multi not supported yet */
-                goto invalid_fld;
-
         /*
          * 12 and 16 byte CDBs use different offsets to
          * provide the various register values.
@@ -2606,6 +2602,22 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
                 tf->device = qc->dev->devno ?
                         tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;
 
+        /* sanity check for pio multi commands */
+        if ((cdb[1] & 0xe0) && !is_multi_taskfile(tf))
+                goto invalid_fld;
+
+        if (is_multi_taskfile(tf)) {
+                unsigned int multi_count = 1 << (cdb[1] >> 5);
+
+                /* compare the passed through multi_count
+                 * with the cached multi_count of libata
+                 */
+                if (multi_count != dev->multi_count)
+                        ata_dev_printk(dev, KERN_WARNING,
+                                       "invalid multi_count %u ignored\n",
+                                       multi_count);
+        }       
+
         /* READ/WRITE LONG use a non-standard sect_size */
         qc->sect_size = ATA_SECT_SIZE;
         switch (tf->command) {
diff --git a/include/linux/ata.h b/include/linux/ata.h
index edb31bfff68f..3e95e5c402d4 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -249,7 +249,7 @@ enum ata_tf_protocols {
         /* ATA taskfile protocols */
         ATA_PROT_UNKNOWN,       /* unknown/invalid */
         ATA_PROT_NODATA,        /* no data */
-        ATA_PROT_PIO,           /* PIO single sector */
+        ATA_PROT_PIO,           /* PIO data xfer */
         ATA_PROT_DMA,           /* DMA */
         ATA_PROT_NCQ,           /* NCQ */
         ATA_PROT_ATAPI,         /* packet command, PIO data xfer*/