[PATCH net-next 2/2] net: dsa: mv88e6xxx: Release mutex between each ATU read

[Andrew Lunn]

The PTP code needs low latency access to the PTP hardware timestamps.
Reading all the ATU entries in one go adds a lot of latency to the PTP
code. So take and release the reg_lock mutex for each individual MAC
address in the ATU, allowing the PTP thread jump in between.

Signed-off-by: Andrew Lunn <and...@lunn.ch>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index bd5cb8a0330e..39c7ad7e490f 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -1437,7 +1437,9 @@ static int mv88e6xxx_port_db_dump_fid(struct 
mv88e6xxx_chip *chip,
        eth_broadcast_addr(addr.mac);
 
        do {
+               mutex_lock(&chip->reg_lock);
                err = mv88e6xxx_g1_atu_getnext(chip, fid, &addr);
+               mutex_unlock(&chip->reg_lock);
                if (err)
                        return err;
 
@@ -1470,7 +1472,10 @@ static int mv88e6xxx_port_db_dump(struct mv88e6xxx_chip 
*chip, int port,
        int err;
 
        /* Dump port's default Filtering Information Database (VLAN ID 0) */
+       mutex_lock(&chip->reg_lock);
        err = mv88e6xxx_port_get_fid(chip, port, &fid);
+       mutex_unlock(&chip->reg_lock);
+
        if (err)
                return err;
 
@@ -1480,7 +1485,9 @@ static int mv88e6xxx_port_db_dump(struct mv88e6xxx_chip 
*chip, int port,
 
        /* Dump VLANs' Filtering Information Databases */
        do {
+               mutex_lock(&chip->reg_lock);
                err = mv88e6xxx_vtu_getnext(chip, &vlan);
+               mutex_unlock(&chip->reg_lock);
                if (err)
                        return err;
 
@@ -1500,13 +1507,8 @@ static int mv88e6xxx_port_fdb_dump(struct dsa_switch 
*ds, int port,
                                   dsa_fdb_dump_cb_t *cb, void *data)
 {
        struct mv88e6xxx_chip *chip = ds->priv;
-       int err;
-
-       mutex_lock(&chip->reg_lock);
-       err = mv88e6xxx_port_db_dump(chip, port, cb, data);
-       mutex_unlock(&chip->reg_lock);
 
-       return err;
+       return mv88e6xxx_port_db_dump(chip, port, cb, data);
 }
 
 static int mv88e6xxx_bridge_map(struct mv88e6xxx_chip *chip,
-- 
2.15.1