[PATCH 3.18 17/26] net: fec: fix multicast filtering hardware setup

From: Greg Kroah-Hartman
Date: Thu Dec 07 2017 - 07:49:45 EST


3.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Rui Sousa <rui.sousa@xxxxxxx>


[ Upstream commit 01f8902bcf3ff124d0aeb88a774180ebcec20ace ]

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: Rui Sousa <rui.sousa@xxxxxxx>
Signed-off-by: Fugang Duan <fugang.duan@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/freescale/fec_main.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)

--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2793,6 +2793,7 @@ static void set_multicast_list(struct ne
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);
@@ -2815,11 +2816,7 @@ static void set_multicast_list(struct ne
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;
@@ -2837,16 +2834,14 @@ static void set_multicast_list(struct ne
*/
hash = (crc >> (32 - 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. */