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net: dsa: sja1105: prepare tagger for handling DSA tags and VLAN simultaneously

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In VLAN-unaware mode, sja1105 uses VLAN tags with a custom TPID of
0xdadb. While in the yet-to-be introduced best_effort_vlan_filtering
mode, it needs to work with normal VLAN TPID values.

A complication arises when we must transmit a VLAN-tagged packet to the
switch when it's in VLAN-aware mode. We need to construct a packet with
2 VLAN tags, and the switch will use the outer header for routing and
pop it on egress. But sadly, here the 2 hardware generations don't
behave the same:

- E/T switches won't pop an ETH_P_8021AD tag on egress, it seems
  (packets will remain double-tagged).
- P/Q/R/S switches will drop a packet with 2 ETH_P_8021Q tags (it looks
  like it tries to prevent VLAN hopping).

But looks like the reverse is also true:

- E/T switches have no problem popping the outer tag from packets with
  2 ETH_P_8021Q tags.
- P/Q/R/S will have no problem popping a single tag even if that is
  ETH_P_8021AD.

So it is clear that if we want the hardware to work with dsa_8021q
tagging in VLAN-aware mode, we need to send different TPIDs depending on
revision. Keep that information in priv->info->qinq_tpid.

The per-port tagger structure will hold an xmit_tpid value that depends
not only upon the qinq_tpid, but also upon the VLAN awareness state
itself (in case we must transmit using 0xdadb).

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vladimir Oltean
2020-05-12 20:20:32 +03:00
committed by David S. Miller
parent cfa36b1fff
commit 38b5beeae7
5 changed files with 44 additions and 11 deletions
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6
drivers/net/dsa/sja1105/sja1105.h
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@@ -87,6 +87,12 @@ struct sja1105_info {
const struct sja1105_dynamic_table_ops *dyn_ops;
const struct sja1105_table_ops *static_ops;
const struct sja1105_regs *regs;
/* Both E/T and P/Q/R/S have quirks when it comes to popping the S-Tag
* from double-tagged frames. E/T will pop it only when it's equal to
* TPID from the General Parameters Table, while P/Q/R/S will only
* pop it when it's equal to TPID2.
*/
u16 qinq_tpid;
int (*reset_cmd)(struct dsa_switch *ds);
int (*setup_rgmii_delay)(const void *ctx, int port);
/* Prototypes from include/net/dsa.h */