From a52cadbf76593f8fcb2f4f62cb006e3f2a22ad06 Mon Sep 17 00:00:00 2001 From: Daniel Golle Date: Mon, 3 Apr 2023 02:19:28 +0100 Subject: [PATCH 11/13] net: dsa: mt7530: skip locking if MDIO bus isn't present As MT7530 and MT7531 internally use 32-bit wide registers, each access to any register of the switch requires several operations on the MDIO bus. Hence if there is congruent access, e.g. due to PCS or PHY polling, this can mess up and interfere with another ongoing register access sequence. However, the MDIO bus mutex is only relevant for MDIO-connected switches. Prepare switches which have there registers directly mapped into the SoCs register space via MMIO which do not require such locking. There we can simply use regmap's default locking mechanism. Hence guard mutex operations to only be performed in case of MDIO connected switches. Signed-off-by: Daniel Golle Reviewed-by: Andrew Lunn Signed-off-by: David S. Miller --- drivers/net/dsa/mt7530.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/net/dsa/mt7530.c +++ b/drivers/net/dsa/mt7530.c @@ -144,13 +144,15 @@ err: static void mt7530_mutex_lock(struct mt7530_priv *priv) { - mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED); + if (priv->bus) + mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED); } static void mt7530_mutex_unlock(struct mt7530_priv *priv) { - mutex_unlock(&priv->bus->mdio_lock); + if (priv->bus) + mutex_unlock(&priv->bus->mdio_lock); } static void