[PATCH net-next v6 17/25] net: dsa: qca8k: clear MASTER_EN after phy read/write

Ansuel Smith
2021-05-14T21:01:48Z

Clear MDIO_MASTER_EN bit from MDIO_MASTER_CTRL after read/write
operation. The MDIO_MASTER_EN bit is not reset after read/write
operation and the next operation can be wrongly interpreted by the
switch as a mdio operation. This cause a production of wrong/garbage
data from the switch and underfined bheavior. (random port drop,
unplugged port flagged with link up, wrong port speed)
Also on driver remove the MASTER_CTRL can be left set and cause the
malfunction of any next driver using the mdio device.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
drivers/net/dsa/qca8k.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index dedbc6565516..a2b4d5097868 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -649,8 +649,14 @@ qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
if (ret)
return ret;

- return qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
- QCA8K_MDIO_MASTER_BUSY);
+ ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
+ QCA8K_MDIO_MASTER_BUSY);
+
+ /* even if the busy_wait timeouts try to clear the MASTER_EN */
+ qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
+ QCA8K_MDIO_MASTER_EN);
+
+ return ret;
}

static int
@@ -685,6 +691,10 @@ qca8k_mdio_read(struct qca8k_priv *priv, int port, u32 regnum)

val &= QCA8K_MDIO_MASTER_DATA_MASK;

+ /* even if the busy_wait timeouts try to clear the MASTER_EN */
+ qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
+ QCA8K_MDIO_MASTER_EN);
+
return val;
}

--
2.30.2