bnx2: Adjust flow control water marks.

The current water marks are too high and can cause unnecessary flow
control frames.
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NBenjamin Li <benli@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/bnx2.c

@@ -1277,7 +1277,7 @@ bnx2_init_rx_context(struct bnx2 *bp, u32 cid)
 		if (lo_water >= bp->rx_ring_size)
 			lo_water = 0;
 
-		hi_water = bp->rx_ring_size / 4;
+		hi_water = min_t(int, bp->rx_ring_size / 4, lo_water + 16);
 
 		if (hi_water <= lo_water)
 			lo_water = 0;

drivers/net/bnx2.h

@@ -349,7 +349,7 @@ struct l2_fhdr {
 #define BNX2_L2CTX_BD_PRE_READ				0x00000000
 #define BNX2_L2CTX_CTX_SIZE				0x00000000
 #define BNX2_L2CTX_CTX_TYPE				0x00000000
-#define BNX2_L2CTX_LO_WATER_MARK_DEFAULT		 32
+#define BNX2_L2CTX_LO_WATER_MARK_DEFAULT		 4
 #define BNX2_L2CTX_LO_WATER_MARK_SCALE			 4
 #define BNX2_L2CTX_LO_WATER_MARK_DIS			 0
 #define BNX2_L2CTX_HI_WATER_MARK_SHIFT			 4