linux-kernel - [PATCH 4.9 087/109] net: fec: fix multicast filtering hardware setup

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Date:   Thu,  7 Dec 2017 13:57:11 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Rui Sousa <rui.sousa@....com>,
        Fugang Duan <fugang.duan@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 087/109] net: fec: fix multicast filtering hardware setup

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

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

From: Rui Sousa <rui.sousa@....com>


[ 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@....com>
Signed-off-by: Fugang Duan <fugang.duan@....com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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
@@ -2923,6 +2923,7 @@ 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);
@@ -2945,11 +2946,7 @@ 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;
@@ -2967,16 +2964,14 @@ static void set_multicast_list(struct ne
 		 */
 		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. */