5.4-stable review patch. If anyone has any objections, please let me know.
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From: Mattias Barthel mattias.barthel@atlascopco.com
[ Upstream commit a179aad12badc43201cbf45d1e8ed2c1383c76b9 ]
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 mattias.barthel@atlascopco.com Reviewed-by: Andrew Lunn andrew@lunn.ch Link: https://patch.msgid.link/20250429090826.3101258-1-mattiasbarthel@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 5660a83356eb0..fd7c504b44f2e 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -605,7 +605,12 @@ 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; }