From 02f18a908b8de64ffb2f18cc8acfd8892bc8b038 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Fri, 9 Aug 2019 08:51:43 +0100 Subject: [PATCH 767/826] net: bcmgenet: Workaround #2 for Pi4 Ethernet fail Some combinations of Pi 4Bs and Ethernet switches don't reliably get a DCHP-assigned IP address, leaving the unit with a self=assigned 169.254 address. In the failure case, the Pi is left able to receive packets but not send them, suggesting that the MAC<->PHY link is getting into a bad state. It has been found empirically that skipping a reset step by the genet driver prevents the failures. No downsides have been discovered yet, and unlike the forced renegotiation it doesn't increase the time to get an IP address, so the workaround is enabled by default; add genet.skip_umac_reset=n to the command line to disable it. See: https://github.com/raspberrypi/linux/issues/3108 Signed-off-by: Phil Elwell --- drivers/net/ethernet/broadcom/genet/bcmgenet.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c index b02f33a2ff08..251166dfb8a8 100644 --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -72,6 +72,10 @@ #define GENET_RDMA_REG_OFF (priv->hw_params->rdma_offset + \ TOTAL_DESC * DMA_DESC_SIZE) +static bool skip_umac_reset = true; +module_param(skip_umac_reset, bool, 0444); +MODULE_PARM_DESC(skip_umac_reset, "Skip UMAC reset step"); + static inline void bcmgenet_writel(u32 value, void __iomem *offset) { /* MIPS chips strapped for BE will automagically configure the @@ -1993,6 +1997,11 @@ static void reset_umac(struct bcmgenet_priv *priv) bcmgenet_rbuf_ctrl_set(priv, 0); udelay(10); + if (skip_umac_reset) { + pr_warn("Skipping UMAC reset\n"); + return; + } + /* disable MAC while updating its registers */ bcmgenet_umac_writel(priv, 0, UMAC_CMD); -- 2.22.0