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net: dsa: mt7530: fix roaming from DSA user ports
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When a client moves from a DSA user port to a software port in a bridge,
it cannot reach any other clients that connected to the DSA user ports.
That is because SA learning on the CPU port is disabled, so the switch
ignores the client's frames from the CPU port and still thinks it is at
the user port.

Fix it by enabling SA learning on the CPU port.

To prevent the switch from learning from flooding frames from the CPU
port, set skb->offload_fwd_mark to 1 for unicast and broadcast frames,
and let the switch flood them instead of trapping to the CPU port.
Multicast frames still need to be trapped to the CPU port for snooping,
so set the SA_DIS bit of the MTK tag to 1 when transmitting those frames
to disable SA learning.

Fixes: b8f126a ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Signed-off-by: DENG Qingfang <dqfext@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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LGA1150 authored and davem330 committed May 16, 2020
1 parent b6dd5ac commit 5e5502e
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Showing 3 changed files with 18 additions and 7 deletions.
9 changes: 2 additions & 7 deletions drivers/net/dsa/mt7530.c
Original file line number Diff line number Diff line change
Expand Up @@ -628,11 +628,8 @@ mt7530_cpu_port_enable(struct mt7530_priv *priv,
mt7530_write(priv, MT7530_PVC_P(port),
PORT_SPEC_TAG);

/* Disable auto learning on the cpu port */
mt7530_set(priv, MT7530_PSC_P(port), SA_DIS);

/* Unknown unicast frame fordwarding to the cpu port */
mt7530_set(priv, MT7530_MFC, UNU_FFP(BIT(port)));
/* Unknown multicast frame forwarding to the cpu port */
mt7530_rmw(priv, MT7530_MFC, UNM_FFP_MASK, UNM_FFP(BIT(port)));

/* Set CPU port number */
if (priv->id == ID_MT7621)
Expand Down Expand Up @@ -1294,8 +1291,6 @@ mt7530_setup(struct dsa_switch *ds)
/* Enable and reset MIB counters */
mt7530_mib_reset(ds);

mt7530_clear(priv, MT7530_MFC, UNU_FFP_MASK);

for (i = 0; i < MT7530_NUM_PORTS; i++) {
/* Disable forwarding by default on all ports */
mt7530_rmw(priv, MT7530_PCR_P(i), PCR_MATRIX_MASK,
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1 change: 1 addition & 0 deletions drivers/net/dsa/mt7530.h
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ enum {
#define MT7530_MFC 0x10
#define BC_FFP(x) (((x) & 0xff) << 24)
#define UNM_FFP(x) (((x) & 0xff) << 16)
#define UNM_FFP_MASK UNM_FFP(~0)
#define UNU_FFP(x) (((x) & 0xff) << 8)
#define UNU_FFP_MASK UNU_FFP(~0)
#define CPU_EN BIT(7)
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15 changes: 15 additions & 0 deletions net/dsa/tag_mtk.c
Original file line number Diff line number Diff line change
Expand Up @@ -15,13 +15,17 @@
#define MTK_HDR_XMIT_TAGGED_TPID_8100 1
#define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
#define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
#define MTK_HDR_XMIT_SA_DIS BIT(6)

static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
u8 *mtk_tag;
bool is_vlan_skb = true;
unsigned char *dest = eth_hdr(skb)->h_dest;
bool is_multicast_skb = is_multicast_ether_addr(dest) &&
!is_broadcast_ether_addr(dest);

/* Build the special tag after the MAC Source Address. If VLAN header
* is present, it's required that VLAN header and special tag is
Expand All @@ -47,6 +51,10 @@ static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
MTK_HDR_XMIT_UNTAGGED;
mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;

/* Disable SA learning for multicast frames */
if (unlikely(is_multicast_skb))
mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;

/* Tag control information is kept for 802.1Q */
if (!is_vlan_skb) {
mtk_tag[2] = 0;
Expand All @@ -61,6 +69,9 @@ static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
{
int port;
__be16 *phdr, hdr;
unsigned char *dest = eth_hdr(skb)->h_dest;
bool is_multicast_skb = is_multicast_ether_addr(dest) &&
!is_broadcast_ether_addr(dest);

if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
return NULL;
Expand All @@ -86,6 +97,10 @@ static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
if (!skb->dev)
return NULL;

/* Only unicast or broadcast frames are offloaded */
if (likely(!is_multicast_skb))
skb->offload_fwd_mark = 1;

return skb;
}

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