[PATCH net 1/2] net: dsa: realtek: rtl8365mb: use IVL in VLAN 0

[Stijn Cleynhens <stijncleynhens@gmail.com>]

DSA installs the FDB and MDB entries of standalone ports and of
VLAN-unaware bridges with VID 0, and the driver writes them with
Independent VLAN Learning. No bridge VLAN sets up the VLAN4k entry of
VID 0 though, and it defaults to Shared VLAN Learning, so the switch
looks up and learns frames classified to VID 0 by FID. Lookups never hit
the IVL-keyed static entries, and a learned entry for the same MAC sits
alongside the static one.

Set up VID 0 with IVL, like every other VLAN the driver programs.

On its own this has no visible effect: standalone ports do not learn and
the driver does not control host flooding, so the unused static entries
only meant that traffic was flooded to the CPU. The next patch, which
moves VLAN-unaware bridges onto VID 0, depends on it.

Fixes: 336e3e4a1ab3 ("net: dsa: realtek: rtl8365mb: add FDB support")
Signed-off-by: Stijn Cleynhens <stijncleynhens@gmail.com>
---
 drivers/net/dsa/realtek/rtl8365mb_main.c |  8 ++++++
 drivers/net/dsa/realtek/rtl8365mb_vlan.c | 31 ++++++++++++++++++++++++
 drivers/net/dsa/realtek/rtl8365mb_vlan.h |  1 +
 3 files changed, 40 insertions(+)

diff --git a/drivers/net/dsa/realtek/rtl8365mb_main.c b/drivers/net/dsa/realtek/rtl8365mb_main.c
index da06f952a..b90e46c16 100644
--- a/drivers/net/dsa/realtek/rtl8365mb_main.c
+++ b/drivers/net/dsa/realtek/rtl8365mb_main.c
@@ -2232,6 +2232,14 @@ static int rtl8365mb_vlan_setup(struct dsa_switch *ds)
 		}
 	}
 
+	mutex_lock(&priv->vlan_lock);
+	ret = rtl8365mb_vlan_4k_setup_neutral(priv);
+	mutex_unlock(&priv->vlan_lock);
+	if (ret) {
+		dev_err(priv->dev, "Failed to set up VLAN 0\n");
+		return ret;
+	}
+
 	/* VLAN is always enabled. */
 	ret = regmap_update_bits(priv->map, RTL8365MB_VLAN_CTRL_REG,
 				 RTL8365MB_VLAN_CTRL_EN_MASK,
diff --git a/drivers/net/dsa/realtek/rtl8365mb_vlan.c b/drivers/net/dsa/realtek/rtl8365mb_vlan.c
index 8d49ffadc..58948e76f 100644
--- a/drivers/net/dsa/realtek/rtl8365mb_vlan.c
+++ b/drivers/net/dsa/realtek/rtl8365mb_vlan.c
@@ -322,6 +322,37 @@ rtl8365mb_vlan_4k_port_set(struct dsa_switch *ds, int port,
 	return 0;
 }
 
+/*
+ * rtl8365mb_vlan_4k_setup_neutral() - Use IVL in the neutral VLAN
+ * @priv: realtek_priv pointer
+ *
+ * Untagged frames of standalone ports and of ports in a VLAN-unaware bridge
+ * are classified to VID 0, the VID of the neutral PVID. No bridge VLAN sets
+ * up its VLAN4k entry, which by default uses Shared VLAN Learning, so the
+ * switch would learn these frames by FID while the driver installs its FDB
+ * and MDB entries for VID 0 with Independent VLAN Learning. Use IVL in VID 0
+ * as in every other VLAN.
+ *
+ * Context: Can sleep. Must be called with &priv->vlan_lock held.
+ * Takes and releases &priv->map_lock.
+ * Return: 0 on success, or a negative error code on failure.
+ */
+int rtl8365mb_vlan_4k_setup_neutral(struct realtek_priv *priv)
+{
+	struct rtl8365mb_vlan4k vlan4k = {0};
+	int ret;
+
+	lockdep_assert_held(&priv->vlan_lock);
+
+	ret = rtl8365mb_vlan_4k_read(priv, 0, &vlan4k);
+	if (ret)
+		return ret;
+
+	vlan4k.ivl_en = true;
+
+	return rtl8365mb_vlan_4k_write(priv, &vlan4k);
+}
+
 /*
  * rtl8365mb_vlan_4k_port_add() - Add a port to a VLAN 4K table entry
  * @ds: dsa switch instance
diff --git a/drivers/net/dsa/realtek/rtl8365mb_vlan.h b/drivers/net/dsa/realtek/rtl8365mb_vlan.h
index 27a526b61..809034009 100644
--- a/drivers/net/dsa/realtek/rtl8365mb_vlan.h
+++ b/drivers/net/dsa/realtek/rtl8365mb_vlan.h
@@ -28,6 +28,7 @@ int
 rtl8365mb_vlan_port_set_framefilter(struct realtek_priv *priv,
 				    int port,
 				    enum rtl8365mb_frame_ingress frame_type);
+int rtl8365mb_vlan_4k_setup_neutral(struct realtek_priv *priv);
 int rtl8365mb_vlan_4k_port_add(struct dsa_switch *ds, int port,
 			       const struct switchdev_obj_port_vlan *vlan,
 			       struct netlink_ext_ack *extack);
-- 
2.56.0