scsi: bnx2fc: Limit the IO size according to the FW capability

- Reduce the sg_tablesize to 255.

 - Reduce the MAX BDs firmware can handle to 255.

 - Return IO to ML if BD goes more then 255 after split.

 - Correct the size of each BD split to 0xffff.

Signed-off-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/bnx2fc/bnx2fc.h

@@ -75,8 +75,9 @@
 #define BNX2X_DOORBELL_PCI_BAR		2
 
 #define BNX2FC_MAX_BD_LEN		0xffff
-#define BNX2FC_BD_SPLIT_SZ		0x8000
-#define BNX2FC_MAX_BDS_PER_CMD		256
+#define BNX2FC_BD_SPLIT_SZ		0xffff
+#define BNX2FC_MAX_BDS_PER_CMD		255
+#define BNX2FC_FW_MAX_BDS_PER_CMD	255
 
 #define BNX2FC_SQ_WQES_MAX	256
 

drivers/scsi/bnx2fc/bnx2fc_fcoe.c

@@ -2971,7 +2971,8 @@ static struct scsi_host_template bnx2fc_shost_template = {
 	.this_id		= -1,
 	.cmd_per_lun		= 3,
 	.sg_tablesize		= BNX2FC_MAX_BDS_PER_CMD,
-	.max_sectors		= 1024,
+	.dma_boundary           = 0x7fff,
+	.max_sectors		= 0x3fbf,
 	.track_queue_depth	= 1,
 	.slave_configure	= bnx2fc_slave_configure,
 	.shost_attrs		= bnx2fc_host_attrs,

drivers/scsi/bnx2fc/bnx2fc_io.c

@@ -1660,6 +1660,7 @@ static int bnx2fc_map_sg(struct bnx2fc_cmd *io_req)
 	u64 addr;
 	int i;
 
+	WARN_ON(scsi_sg_count(sc) > BNX2FC_MAX_BDS_PER_CMD);
 	/*
 	 * Use dma_map_sg directly to ensure we're using the correct
 	 * dev struct off of pcidev.
@@ -1707,6 +1708,16 @@ static int bnx2fc_build_bd_list_from_sg(struct bnx2fc_cmd *io_req)
 	}
 	io_req->bd_tbl->bd_valid = bd_count;
 
+	/*
+	 * Return the command to ML if BD count exceeds the max number
+	 * that can be handled by FW.
+	 */
+	if (bd_count > BNX2FC_FW_MAX_BDS_PER_CMD) {
+		pr_err("bd_count = %d exceeded FW supported max BD(255), task_id = 0x%x\n",
+		       bd_count, io_req->xid);
+		return -ENOMEM;
+	}
+
 	return 0;
 }