[PATCH net-next 2/2] net: dsa: mv88e6xxx: Only allow LAG offload on supported hardware

[Tobias Waldekranz]

There are chips that do have Global 2 registers, and therefore trunk
mapping/mask tables are not available. Additionally Global 2 register
support is build-time optional, so we have to make sure that it is
compiled in.

Fixes: 57e661aae6a8 ("net: dsa: mv88e6xxx: Link aggregation support")
Signed-off-by: Tobias Waldekranz <tob...@waldekranz.com>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 4 ++++
 drivers/net/dsa/mv88e6xxx/chip.h | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index dcb1726b68cc..c48d166c2a70 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -5385,9 +5385,13 @@ static bool mv88e6xxx_lag_can_offload(struct dsa_switch 
*ds,
                                      struct net_device *lag,
                                      struct netdev_lag_upper_info *info)
 {
+       struct mv88e6xxx_chip *chip = ds->priv;
        struct dsa_port *dp;
        int id, members = 0;
 
+       if (!mv88e6xxx_has_lag(chip))
+               return false;
+
        id = dsa_lag_id(ds->dst, lag);
        if (id < 0 || id >= ds->num_lag_ids)
                return false;
diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 3543055bcb51..333b4fab5aa2 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -662,6 +662,15 @@ static inline bool mv88e6xxx_has_pvt(struct mv88e6xxx_chip 
*chip)
        return chip->info->pvt;
 }
 
+static inline bool mv88e6xxx_has_lag(struct mv88e6xxx_chip *chip)
+{
+#if (defined(CONFIG_NET_DSA_MV88E6XXX_GLOBAL2))
+       return chip->info->global2_addr != 0;
+#else
+       return false;
+#endif
+}
+
 static inline unsigned int mv88e6xxx_num_databases(struct mv88e6xxx_chip *chip)
 {
        return chip->info->num_databases;
-- 
2.17.1