The mt7530_{r,w}32 operation over MDIO uses 3 mdiobus operations and
does not hold a lock, which causes a race condition when multiple
threads try to access a register, they may get unexpected results.
To avoid this, handle the MDIO lock manually, and use the unlocked
__mdiobus_{read,write} in the critical section.
This fixes the "Ghost VLAN" artifact[1] in MT7530/7621 when the VLAN
operation and the swconfig LED link status poll race between each other.
[1] https://forum.openwrt.org/t/mysterious-vlan-ids-on-mt7621-device/64495
Signed-off-by: DENG Qingfang <[email protected]>
---
Please backport this to 21.02/19.07, thanks!
.../files/drivers/net/ethernet/ralink/mt7530.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/target/linux/ramips/files/drivers/net/ethernet/ralink/mt7530.c
b/target/linux/ramips/files/drivers/net/ethernet/ralink/mt7530.c
index be1b8a6d8e..b4632d3990 100644
--- a/target/linux/ramips/files/drivers/net/ethernet/ralink/mt7530.c
+++ b/target/linux/ramips/files/drivers/net/ethernet/ralink/mt7530.c
@@ -290,9 +290,11 @@ mt7530_r32(struct mt7530_priv *priv, u32 reg)
if (priv->bus) {
u16 high, low;
- mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff);
- low = mdiobus_read(priv->bus, 0x1f, (reg >> 2) & 0xf);
- high = mdiobus_read(priv->bus, 0x1f, 0x10);
+ mutex_lock(&priv->bus->mdio_lock);
+ __mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff);
+ low = __mdiobus_read(priv->bus, 0x1f, (reg >> 2) & 0xf);
+ high = __mdiobus_read(priv->bus, 0x1f, 0x10);
+ mutex_unlock(&priv->bus->mdio_lock);
return (high << 16) | (low & 0xffff);
}
@@ -307,9 +309,11 @@ static void
mt7530_w32(struct mt7530_priv *priv, u32 reg, u32 val)
{
if (priv->bus) {
- mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff);
- mdiobus_write(priv->bus, 0x1f, (reg >> 2) & 0xf, val & 0xffff);
- mdiobus_write(priv->bus, 0x1f, 0x10, val >> 16);
+ mutex_lock(&priv->bus->mdio_lock);
+ __mdiobus_write(priv->bus, 0x1f, 0x1f, (reg >> 6) & 0x3ff);
+ __mdiobus_write(priv->bus, 0x1f, (reg >> 2) & 0xf, val &
0xffff);
+ __mdiobus_write(priv->bus, 0x1f, 0x10, val >> 16);
+ mutex_unlock(&priv->bus->mdio_lock);
return;
}
--
2.25.1
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