From 960e77ce14a83ef7f226e8e4b4d75765633ba48b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Nerijus=20Bend=C5=BEi=C5=ABnas?= Date: Sat, 16 May 2026 18:02:51 +0300 Subject: [PATCH] net: phy: skip EEE advertisement write when autoneg is disabled MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit genphy_c45_an_config_eee_aneg() writes the EEE advertisement to the auto-negotiation device's MMD register space (MDIO_MMD_AN, register MDIO_AN_EEE_ADV). These registers are read by the link partner only during auto-negotiation, so writing them while autoneg is disabled cannot influence the link. On some PHYs (e.g. Broadcom BCM54213PE) the write nevertheless reaches the chip and disturbs the receive datapath. Concretely, running ethtool -s eth0 speed 100 duplex full autoneg off ethtool --set-eee eth0 eee off leaves eth0 with TX working and RX completely silent on a Raspberry Pi 4 / CM4 board (bcmgenet + BCM54213PE in rgmii-rxid). Switching back to autoneg recovers the link. Prior to commit f26a29a038ee ("net: phy: ensure that genphy_c45_an_config_eee_aneg() sees new value of phydev->eee_cfg.eee_enabled"), the disable path was effectively a no-op because the helper read the stale eee_cfg.eee_enabled, so the underlying PHY behavior never surfaced. Bisected on rpi-6.12.y between commits 83943264 (good) and effcbc88 (bad) to f26a29a038ee. Fixes: f26a29a038ee ("net: phy: ensure that genphy_c45_an_config_eee_aneg() sees new value of phydev->eee_cfg.eee_enabled") Cc: stable@vger.kernel.org Signed-off-by: Nerijus Bendžiūnas Reviewed-by: Nicolai Buchwitz Tested-by: Nicolai Buchwitz Link: https://patch.msgid.link/20260516150251.879680-1-nerijus.bendziunas@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/phy/phy-c45.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c index d48aa7231b37..126951741428 100644 --- a/drivers/net/phy/phy-c45.c +++ b/drivers/net/phy/phy-c45.c @@ -940,6 +940,14 @@ EXPORT_SYMBOL_GPL(genphy_c45_read_eee_abilities); */ int genphy_c45_an_config_eee_aneg(struct phy_device *phydev) { + /* Writing MMD AN advertisements while autoneg is disabled has no + * effect on link-partner negotiation, but on some PHYs (e.g. the + * Broadcom BCM54213PE) the write itself disturbs the receive + * datapath. Skip it. + */ + if (phydev->autoneg == AUTONEG_DISABLE) + return 0; + if (!phydev->eee_cfg.eee_enabled) { __ETHTOOL_DECLARE_LINK_MODE_MASK(adv) = {};