From 3fb8841513c4ec3a2e5d366df86230c45f239a57 Mon Sep 17 00:00:00 2001
From: Alexander Couzens <lynxis@fe80.eu>
Date: Sat, 13 Aug 2022 13:08:22 +0200
Subject: [PATCH 03/10] net: mt7531: ensure all MACs are powered down before
 reset

The datasheet [1] explicit describes it as requirement for a reset.

[1] MT7531 Reference Manual for Development Board rev 1.0, page 735

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
---
 drivers/net/dsa/mt7530.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2422,7 +2422,7 @@ mt7531_setup(struct dsa_switch *ds)
 	struct mt7530_priv *priv = ds->priv;
 	struct mt7530_dummy_poll p;
 	u32 val, id;
-	int ret;
+	int ret, i;
 
 	/* Reset whole chip through gpio pin or memory-mapped registers for
 	 * different type of hardware
@@ -2454,6 +2454,10 @@ mt7531_setup(struct dsa_switch *ds)
 		return -ENODEV;
 	}
 
+	/* all MACs must be forced link-down before sw reset */
+	for (i = 0; i < MT7530_NUM_PORTS; i++)
+		mt7530_write(priv, MT7530_PMCR_P(i), MT7531_FORCE_LNK);
+
 	/* Reset the switch through internal reset */
 	mt7530_write(priv, MT7530_SYS_CTRL,
 		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
