From 103fdd9ca2033f18c5f8584e72db65a74d7dbd52 Mon Sep 17 00:00:00 2001 From: Nicolai Buchwitz Date: Wed, 20 May 2026 09:13:18 +0200 Subject: [PATCH] net: bcmgenet: keep RBUF EEE/PM disabled Setting RBUF_EEE_EN | RBUF_PM_EN in RBUF_ENERGY_CTRL breaks the RX path on GENET hardware once MAC EEE becomes active. RX traffic stops flowing while the link stays up and the usual descriptor/RX error counters remain quiet. In that state the MAC still accepts frames (rbuf_ovflow_cnt keeps climbing) but RBUF no longer forwards them to DMA, so rx_packets is no longer incremented at the netdev level. On some boards the corruption ends up as a paging fault in skb_release_data via bcmgenet_rx_poll on an LPI exit. Reproduced on Pi 4B (BCM2711 + BCM54213PE) and confirmed by Florian Fainelli on an internal Broadcom 4908-family board with the same crash signature. RBUF_PM_EN is not publicly documented. This shows up more often now that phy_support_eee() enables EEE by default, but it also affects older kernels as soon as TX LPI is turned on via ethtool, so it is not specific to recent changes. Always clear RBUF_EEE_EN | RBUF_PM_EN in bcmgenet_eee_enable_set so the bits stay off across resets. UMAC and TBUF setup is left alone so TX-side EEE keeps working. Link: https://github.com/raspberrypi/linux/issues/7304 Fixes: 6ef398ea60d9 ("net: bcmgenet: add EEE support") Cc: stable@vger.kernel.org Signed-off-by: Nicolai Buchwitz --- drivers/net/ethernet/broadcom/genet/bcmgenet.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c index 3b8a062004b733..d8d3a720d5ccab 100644 --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -1369,13 +1369,12 @@ void bcmgenet_eee_enable_set(struct net_device *dev, bool enable) reg &= ~(TBUF_EEE_EN | TBUF_PM_EN); bcmgenet_writel(reg, priv->base + off); - /* Do the same for thing for RBUF */ + /* RBUF EEE/PM can break the RX path on GENET. Keep it disabled. */ reg = bcmgenet_rbuf_readl(priv, RBUF_ENERGY_CTRL); - if (enable) - reg |= RBUF_EEE_EN | RBUF_PM_EN; - else + if (reg & (RBUF_EEE_EN | RBUF_PM_EN)) { reg &= ~(RBUF_EEE_EN | RBUF_PM_EN); - bcmgenet_rbuf_writel(priv, reg, RBUF_ENERGY_CTRL); + bcmgenet_rbuf_writel(priv, reg, RBUF_ENERGY_CTRL); + } if (!enable && priv->clk_eee_enabled) { clk_disable_unprepare(priv->clk_eee);