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>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 95a57aeb466e9a69ee9a83c368282006499546e9..409d5c3d76ea6fee386466a16578676bc0b6720a 100644 (file)
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2329,6 +2329,10 @@ 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 |