When servicing ATU violations we need to walk the VTU to find the vlan
id for the ATU's FID which is inefficient.

Add a cache for this association and replace the VTU walk so we don't
have to do this costly operation all the time.

Signed-off-by: Elliot Ayrey <elliot.ayrey@alliedtelesis.co.nz>
---
 drivers/net/dsa/mv88e6xxx/chip.h        |  2 ++
 drivers/net/dsa/mv88e6xxx/global1_vtu.c |  6 ++++-
 drivers/net/dsa/mv88e6xxx/switchdev.c   | 35 ++-----------------------
 3 files changed, 9 insertions(+), 34 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 48399ab5355a..91c3e4b304cf 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -445,6 +445,8 @@ struct mv88e6xxx_chip {
 
 	/* FID map */
 	DECLARE_BITMAP(fid_bitmap, MV88E6XXX_N_FID);
+
+	u16 vid_cache[MV88E6XXX_N_FID];
 };
 
 struct mv88e6xxx_bus_ops {
diff --git a/drivers/net/dsa/mv88e6xxx/global1_vtu.c b/drivers/net/dsa/mv88e6xxx/global1_vtu.c
index b524f27a2f0d..af1c40480303 100644
--- a/drivers/net/dsa/mv88e6xxx/global1_vtu.c
+++ b/drivers/net/dsa/mv88e6xxx/global1_vtu.c
@@ -464,7 +464,11 @@ int mv88e6390_g1_vtu_loadpurge(struct mv88e6xxx_chip *chip,
 	}
 
 	/* Load/Purge VTU entry */
-	return mv88e6xxx_g1_vtu_op(chip, MV88E6XXX_G1_VTU_OP_VTU_LOAD_PURGE);
+	err = mv88e6xxx_g1_vtu_op(chip, MV88E6XXX_G1_VTU_OP_VTU_LOAD_PURGE);
+	if (err == 0)
+		chip->vid_cache[entry->fid] = entry->valid ? entry->vid : 0;
+
+	return err;
 }
 
 int mv88e6xxx_g1_vtu_flush(struct mv88e6xxx_chip *chip)
diff --git a/drivers/net/dsa/mv88e6xxx/switchdev.c b/drivers/net/dsa/mv88e6xxx/switchdev.c
index 88761677ff10..e96daa2dcaf4 100644
--- a/drivers/net/dsa/mv88e6xxx/switchdev.c
+++ b/drivers/net/dsa/mv88e6xxx/switchdev.c
@@ -12,42 +12,11 @@
 #include "global1.h"
 #include "switchdev.h"
 
-struct mv88e6xxx_fid_search_ctx {
-	u16 fid_search;
-	u16 vid_found;
-};
-
-static int __mv88e6xxx_find_vid(struct mv88e6xxx_chip *chip,
-				const struct mv88e6xxx_vtu_entry *entry,
-				void *priv)
-{
-	struct mv88e6xxx_fid_search_ctx *ctx = priv;
-
-	if (ctx->fid_search == entry->fid) {
-		ctx->vid_found = entry->vid;
-		return 1;
-	}
-
-	return 0;
-}
-
 static int mv88e6xxx_find_vid(struct mv88e6xxx_chip *chip, u16 fid, u16 *vid)
 {
-	struct mv88e6xxx_fid_search_ctx ctx;
-	int err;
-
-	ctx.fid_search = fid;
-	mv88e6xxx_reg_lock(chip);
-	err = mv88e6xxx_vtu_walk(chip, __mv88e6xxx_find_vid, &ctx);
-	mv88e6xxx_reg_unlock(chip);
-	if (err < 0)
-		return err;
-	if (err == 1)
-		*vid = ctx.vid_found;
-	else
-		return -ENOENT;
+	*vid = chip->vid_cache[fid];
 
-	return 0;
+	return *vid ? 0 : -ENOENT;
 }
 
 int mv88e6xxx_handle_miss_violation(struct mv88e6xxx_chip *chip, int port,