[SCSI] mvsas: expander write performance enhancement

with 1 expander, connect 8 HDD, the write performance will be
improved by 80%.

Signed-off-by: Xiangliang Yu <yuxiangl@marvell.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/mvsas/mv_94xx.c

@@ -510,6 +510,15 @@ static int __devinit mvs_94xx_init(struct mvs_info *mvi)
 	tmp |= CINT_PHY_MASK;
 	mw32(MVS_INT_MASK, tmp);
 
+	/* tune STP performance */
+	tmp = 0x003F003F;
+	mvs_cw32(mvi, CMD_PL_TIMER, tmp);
+
+	/* This can improve expander large block size seq write performance */
+	tmp = mvs_cr32(mvi, CMD_PORT_LAYER_TIMER1);
+	tmp |= 0xFFFF007F;
+	mvs_cw32(mvi, CMD_PORT_LAYER_TIMER1, tmp);
+
 	/* change the connection open-close behavior (bit 9)
 	 * set bit8 to 1 for performance tuning */
 	tmp = mvs_cr32(mvi, CMD_SL_MODE0);

drivers/scsi/mvsas/mv_defs.h

@@ -387,6 +387,7 @@ enum sas_cmd_port_registers {
 	CMD_SL_MODE0		= 0x1BC, /* SL Mode 0 */
 	CMD_SL_MODE1		= 0x1C0, /* SL Mode 1 */
 	CMD_PND_FIFO_CTL1	= 0x1C4, /* Pending FIFO Control 1 */
+	CMD_PORT_LAYER_TIMER1	= 0x1E0, /* Port Layer Timer 1 */
 };
 
 enum mvs_info_flags {