[PATCH net 2/3] net: dsa: mt7530: error out on failed reads in ATC/VTCR command polling

[Daniel Golle]

mt7530_fdb_cmd() and mt7530_vlan_cmd() poll the command register
through a helper which returns 0 when the underlying read fails. A
failed bus transaction thus clears ATC_BUSY/VTCR_BUSY and is treated
as successful command completion, and the subsequent ATC_INVALID and
VTCR_INVALID checks are defeated the same way.

Poll using regmap_read_poll_timeout(), which stops on read errors and
propagates them, and check the completion status read as well. Take
the MDIO bus lock across the sequence as the switch regmap is set up
with locking disabled.

Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Fixes: 83163f7dca56 ("net: dsa: mediatek: add VLAN support for MT7530")
Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
---
 drivers/net/dsa/mt7530.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 6c8ed00ee9e7..51555060b5eb 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -248,15 +248,20 @@ mt7530_fdb_cmd(struct mt7530_priv *priv, enum mt7530_fdb_cmd cmd, u32 *rsp)
 {
 	u32 val;
 	int ret;
-	struct mt7530_dummy_poll p;
 
 	/* Set the command operating upon the MAC address entries */
 	val = ATC_BUSY | ATC_MAT(0) | cmd;
 	mt7530_write(priv, MT7530_ATC, val);
 
-	INIT_MT7530_DUMMY_POLL(&p, priv, MT7530_ATC);
-	ret = readx_poll_timeout(_mt7530_read, &p, val,
-				 !(val & ATC_BUSY), 20, 20000);
+	mt7530_mutex_lock(priv);
+
+	ret = regmap_read_poll_timeout(priv->regmap, MT7530_ATC, val,
+				       !(val & ATC_BUSY), 20, 20000);
+	if (!ret)
+		ret = regmap_read(priv->regmap, MT7530_ATC, &val);
+
+	mt7530_mutex_unlock(priv);
+
 	if (ret < 0) {
 		dev_err(priv->dev, "reset timeout\n");
 		return ret;
@@ -265,7 +270,6 @@ mt7530_fdb_cmd(struct mt7530_priv *priv, enum mt7530_fdb_cmd cmd, u32 *rsp)
 	/* Additional sanity for read command if the specified
 	 * entry is invalid
 	 */
-	val = mt7530_read(priv, MT7530_ATC);
 	if ((cmd == MT7530_FDB_READ) && (val & ATC_INVALID))
 		return -EINVAL;
 
@@ -1626,22 +1630,26 @@ mt7530_port_bridge_join(struct dsa_switch *ds, int port,
 static int
 mt7530_vlan_cmd(struct mt7530_priv *priv, enum mt7530_vlan_cmd cmd, u16 vid)
 {
-	struct mt7530_dummy_poll p;
 	u32 val;
 	int ret;
 
 	val = VTCR_BUSY | VTCR_FUNC(cmd) | vid;
 	mt7530_write(priv, MT7530_VTCR, val);
 
-	INIT_MT7530_DUMMY_POLL(&p, priv, MT7530_VTCR);
-	ret = readx_poll_timeout(_mt7530_read, &p, val,
-				 !(val & VTCR_BUSY), 20, 20000);
+	mt7530_mutex_lock(priv);
+
+	ret = regmap_read_poll_timeout(priv->regmap, MT7530_VTCR, val,
+				       !(val & VTCR_BUSY), 20, 20000);
+	if (!ret)
+		ret = regmap_read(priv->regmap, MT7530_VTCR, &val);
+
+	mt7530_mutex_unlock(priv);
+
 	if (ret < 0) {
 		dev_err(priv->dev, "poll timeout\n");
 		return ret;
 	}
 
-	val = mt7530_read(priv, MT7530_VTCR);
 	if (val & VTCR_INVALID) {
 		dev_err(priv->dev, "read VTCR invalid\n");
 		return -EINVAL;
-- 
2.55.0