if we run out of mbufs for the rx ring, run a timeout to refill them

claudio@ (i think) hit this a while back, and i've had this diff
in my tree since then. i'm putting it in now since it empirically
solved the problem and im sick of carrying the diff around.

1 files changed, 44 insertions, 5 deletions

diff --git a/sys/dev/fdt/if_dwxe.c b/sys/dev/fdt/if_dwxe.c
index 3a561f76968..d39bde3e3f3 100644
--- a/sys/dev/fdt/if_dwxe.c
+++ b/sys/dev/fdt/if_dwxe.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_dwxe.c,v 1.10 2018/08/06 10:52:30 patrick Exp $	*/
+/*	$OpenBSD: if_dwxe.c,v 1.11 2019/01/03 00:59:58 dlg Exp $	*/
 /*
  * Copyright (c) 2008 Mark Kettenis
  * Copyright (c) 2017 Patrick Wildt <patrick@blueri.se>
@@ -298,6 +298,7 @@ struct dwxe_softc {
 	int			sc_rx_cons;
 
 	struct timeout		sc_tick;
+	struct timeout		sc_rxto;
 
 	uint32_t		sc_clk;
 };
@@ -335,6 +336,7 @@ void	dwxe_lladdr_read(struct dwxe_softc *, uint8_t *);
 void	dwxe_lladdr_write(struct dwxe_softc *);
 
 void	dwxe_tick(void *);
+void	dwxe_rxtick(void *);
 
 int	dwxe_intr(void *);
 void	dwxe_tx_proc(struct dwxe_softc *);
@@ -423,6 +425,7 @@ dwxe_attach(struct device *parent, struct device *self, void *aux)
 		dwxe_phy_setup_emac(sc);
 
 	timeout_set(&sc->sc_tick, dwxe_tick, sc);
+	timeout_set(&sc->sc_rxto, dwxe_rxtick, sc);
 
 	ifp = &sc->sc_ac.ac_if;
 	ifp->if_softc = sc;
@@ -812,6 +815,37 @@ dwxe_tick(void *arg)
 	timeout_add_sec(&sc->sc_tick, 1);
 }
 
+void
+dwxe_rxtick(void *arg)
+{
+	struct dwxe_softc *sc = arg;
+	uint32_t ctl;
+	int s;
+
+	s = splnet();
+
+	ctl = dwxe_read(sc, DWXE_RX_CTL1);
+	dwxe_write(sc, DWXE_RX_CTL1, ctl & ~DWXE_RX_CTL1_RX_DMA_EN);
+
+	bus_dmamap_sync(sc->sc_dmat, DWXE_DMA_MAP(sc->sc_rxring),
+	    0, DWXE_DMA_LEN(sc->sc_rxring),
+	    BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);
+
+	dwxe_write(sc, DWXE_RX_DESC_LIST, 0);
+
+	sc->sc_rx_prod = sc->sc_rx_cons = 0;
+	dwxe_fill_rx_ring(sc);
+
+	bus_dmamap_sync(sc->sc_dmat, DWXE_DMA_MAP(sc->sc_rxring),
+	    0, DWXE_DMA_LEN(sc->sc_rxring),
+	    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
+
+	dwxe_write(sc, DWXE_RX_DESC_LIST, DWXE_DMA_DVA(sc->sc_rxring));
+	dwxe_write(sc, DWXE_RX_CTL1, ctl);
+
+	splx(s);
+}
+
 int
 dwxe_intr(void *arg)
 {
@@ -989,14 +1023,15 @@ dwxe_up(struct dwxe_softc *sc)
 		    ((i+1) % DWXE_NRXDESC) * sizeof(struct dwxe_desc);
 	}
 
-	bus_dmamap_sync(sc->sc_dmat, DWXE_DMA_MAP(sc->sc_rxring),
-	    0, DWXE_DMA_LEN(sc->sc_rxring), BUS_DMASYNC_PREWRITE);
+	if_rxr_init(&sc->sc_rx_ring, 2, DWXE_NRXDESC);
 
 	sc->sc_rx_prod = sc->sc_rx_cons = 0;
-
-	if_rxr_init(&sc->sc_rx_ring, 2, DWXE_NRXDESC);
 	dwxe_fill_rx_ring(sc);
 
+	bus_dmamap_sync(sc->sc_dmat, DWXE_DMA_MAP(sc->sc_rxring),
+	    0, DWXE_DMA_LEN(sc->sc_rxring),
+	    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
+
 	dwxe_write(sc, DWXE_RX_DESC_LIST, DWXE_DMA_DVA(sc->sc_rxring));
 
 	dwxe_lladdr_write(sc);
@@ -1038,6 +1073,7 @@ dwxe_down(struct dwxe_softc *sc)
 	uint32_t dmactrl;
 	int i;
 
+	timeout_del(&sc->sc_rxto);
 	timeout_del(&sc->sc_tick);
 
 	ifp->if_flags &= ~IFF_RUNNING;
@@ -1344,4 +1380,7 @@ dwxe_fill_rx_ring(struct dwxe_softc *sc)
 			sc->sc_rx_prod++;
 	}
 	if_rxr_put(&sc->sc_rx_ring, slots);
+
+	if (if_rxr_inuse(&sc->sc_rx_ring) == 0)
+		timeout_add(&sc->sc_rxto, 1);
 }