From 555d2e798de591dc2abe73159ee704bfb77822ca Mon Sep 17 00:00:00 2001 From: uwe Date: Thu, 28 Dec 2023 14:30:28 +0000 Subject: [PATCH] fix Tx watchdog trigger and freeze in dwqe(4) dwqe(4) interfaces may trigger the "dwqe_watchdog" function and stop transmitting packets under heavy Tx load. In this situation, ifconfig(8) will permanently show OACTIVE until the interface is restarted (ifconfig down/up). The problem seems to be triggered by writing to the Tx ring tail pointer register multiple times during dwqe_start(). Updating the Tx ring tail pointer only after all Tx descriptors have been updated seems to fix it. The fix is based on the eqos(4) driver in NetBSD. Verified on an Intel Elkhart Lake machine but might affect other platforms with DesignWare Ethernet Quality-of-Service Controller version 4. Testing by bluhm@, ok kettenis@ --- sys/dev/ic/dwqe.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/sys/dev/ic/dwqe.c b/sys/dev/ic/dwqe.c index f853fcc109f..e515fd03374 100644 --- a/sys/dev/ic/dwqe.c +++ b/sys/dev/ic/dwqe.c @@ -1,4 +1,4 @@ -/* $OpenBSD: dwqe.c,v 1.15 2023/11/10 15:51:20 bluhm Exp $ */ +/* $OpenBSD: dwqe.c,v 1.16 2023/12/28 14:30:28 uwe Exp $ */ /* * Copyright (c) 2008, 2019 Mark Kettenis * Copyright (c) 2017, 2022 Patrick Wildt @@ -338,11 +338,18 @@ dwqe_start(struct ifqueue *ifq) #endif } - if (sc->sc_tx_prod != idx) { + if (used > 0) { sc->sc_tx_prod = idx; /* Set a timeout in case the chip goes out to lunch. */ ifp->if_timer = 5; + + /* + * Start the transmit process after the last in-use Tx + * descriptor's OWN bit has been updated. + */ + dwqe_write(sc, GMAC_CHAN_TX_END_ADDR(0), DWQE_DMA_DVA(sc->sc_txring) + + idx * sizeof(struct dwqe_desc)); } } @@ -1055,9 +1062,6 @@ dwqe_encap(struct dwqe_softc *sc, struct mbuf *m, int *idx, int *used) bus_dmamap_sync(sc->sc_dmat, DWQE_DMA_MAP(sc->sc_txring), *idx * sizeof(*txd), sizeof(*txd), BUS_DMASYNC_PREWRITE); - dwqe_write(sc, GMAC_CHAN_TX_END_ADDR(0), DWQE_DMA_DVA(sc->sc_txring) + - frag * sizeof(*txd)); - KASSERT(sc->sc_txbuf[cur].tb_m == NULL); sc->sc_txbuf[*idx].tb_map = sc->sc_txbuf[cur].tb_map; sc->sc_txbuf[cur].tb_map = map; -- 2.20.1