[PATCH net 1/3] net: dsa: mt7530: check bus->read() errors in the MDIO regmap backend
From: Daniel Golle <daniel@makrotopia.org>
Date: 2026-07-28 04:52:34
Also in:
linux-arm-kernel, linux-mediatek, lkml
Subsystem:
mediatek switch driver, networking drivers, networking [dsa], the rest · Maintainers:
Chester A. Unal, Daniel Golle, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Andrew Lunn, Vladimir Oltean, Linus Torvalds
bus->read() returns a negative errno on failure, but
mt7530_regmap_read() assigns it to a u16, truncating e.g. -ETIMEDOUT
into 0xff92, and returns success. The garbage word is then consumed as
register data, and read-modify-write cycles write it back to the
switch. Check both reads and propagate their errors.
The same defect existed in mt7530_mii_read() since the driver was
introduced and moved into the regmap backend unchanged.
Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
drivers/net/dsa/mt7530-mdio.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/net/dsa/mt7530-mdio.c b/drivers/net/dsa/mt7530-mdio.c
index 11ea924a9f35..784dd58a7158 100644
--- a/drivers/net/dsa/mt7530-mdio.c
+++ b/drivers/net/dsa/mt7530-mdio.c@@ -55,8 +55,15 @@ mt7530_regmap_read(void *context, unsigned int reg, unsigned int *val) if (ret < 0) return ret; - lo = bus->read(bus, priv->mdiodev->addr, r); - hi = bus->read(bus, priv->mdiodev->addr, 0x10); + ret = bus->read(bus, priv->mdiodev->addr, r); + if (ret < 0) + return ret; + lo = ret; + + ret = bus->read(bus, priv->mdiodev->addr, 0x10); + if (ret < 0) + return ret; + hi = ret; *val = (hi << 16) | (lo & 0xffff);
--
2.55.0