[PATCH net 1/1] net: fec: fix multicast filtering hardware setup

[Andy Duan]

Fix hardware setup of multicast address hash:
- Never clear the hardware hash (to avoid packet loss)
- Construct the hash register values in software and then write once
to hardware

Signed-off-by: Fugang Duan <fugang.d...@nxp.com>
Signed-off-by: Rui Sousa <rui.so...@nxp.com>
---
 drivers/net/ethernet/freescale/fec_main.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c 
b/drivers/net/ethernet/freescale/fec_main.c
index 2cc552d..91a1664 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2910,6 +2910,7 @@ static void set_multicast_list(struct net_device *ndev)
        struct netdev_hw_addr *ha;
        unsigned int i, bit, data, crc, tmp;
        unsigned char hash;
+       unsigned int hash_high = 0, hash_low = 0;
 
        if (ndev->flags & IFF_PROMISC) {
                tmp = readl(fep->hwp + FEC_R_CNTRL);
@@ -2932,11 +2933,7 @@ static void set_multicast_list(struct net_device *ndev)
                return;
        }
 
-       /* Clear filter and add the addresses in hash register
-        */
-       writel(0, fep->hwp + FEC_GRP_HASH_TABLE_HIGH);
-       writel(0, fep->hwp + FEC_GRP_HASH_TABLE_LOW);
-
+       /* Add the addresses in hash register */
        netdev_for_each_mc_addr(ha, ndev) {
                /* calculate crc32 value of mac address */
                crc = 0xffffffff;
@@ -2954,16 +2951,14 @@ static void set_multicast_list(struct net_device *ndev)
                 */
                hash = (crc >> (32 - FEC_HASH_BITS)) & 0x3f;
 
-               if (hash > 31) {
-                       tmp = readl(fep->hwp + FEC_GRP_HASH_TABLE_HIGH);
-                       tmp |= 1 << (hash - 32);
-                       writel(tmp, fep->hwp + FEC_GRP_HASH_TABLE_HIGH);
-               } else {
-                       tmp = readl(fep->hwp + FEC_GRP_HASH_TABLE_LOW);
-                       tmp |= 1 << hash;
-                       writel(tmp, fep->hwp + FEC_GRP_HASH_TABLE_LOW);
-               }
+               if (hash > 31)
+                       hash_high |= 1 << (hash - 32);
+               else
+                       hash_low |= 1 << hash;
        }
+
+       writel(hash_high, fep->hwp + FEC_GRP_HASH_TABLE_HIGH);
+       writel(hash_low, fep->hwp + FEC_GRP_HASH_TABLE_LOW);
 }
 
 /* Set a MAC change in hardware. */
-- 
1.9.1