From a179aad12badc43201cbf45d1e8ed2c1383c76b9 Mon Sep 17 00:00:00 2001 From: Mattias Barthel Date: Tue, 29 Apr 2025 11:08:26 +0200 Subject: [PATCH] net: fec: ERR007885 Workaround for conventional TX Activate TX hang workaround also in fec_enet_txq_submit_skb() when TSO is not enabled. Errata: ERR007885 Symptoms: NETDEV WATCHDOG: eth0 (fec): transmit queue 0 timed out commit 37d6017b84f7 ("net: fec: Workaround for imx6sx enet tx hang when enable three queues") There is a TDAR race condition for mutliQ when the software sets TDAR and the UDMA clears TDAR simultaneously or in a small window (2-4 cycles). This will cause the udma_tx and udma_tx_arbiter state machines to hang. So, the Workaround is checking TDAR status four time, if TDAR cleared by hardware and then write TDAR, otherwise don't set TDAR. Fixes: 53bb20d1faba ("net: fec: add variable reg_desc_active to speed things up") Signed-off-by: Mattias Barthel Reviewed-by: Andrew Lunn Link: https://patch.msgid.link/20250429090826.3101258-1-mattiasbarthel@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/freescale/fec_main.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index a86cfebedaa8b..17e9bddb9ddd5 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -714,7 +714,12 @@ static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq, txq->bd.cur = bdp; /* Trigger transmission start */ - writel(0, txq->bd.reg_desc_active); + if (!(fep->quirks & FEC_QUIRK_ERR007885) || + !readl(txq->bd.reg_desc_active) || + !readl(txq->bd.reg_desc_active) || + !readl(txq->bd.reg_desc_active) || + !readl(txq->bd.reg_desc_active)) + writel(0, txq->bd.reg_desc_active); return 0; } -- 2.39.5