From 430d5eb47db5cc30bde17bbc9c53479145c0d8ca Mon Sep 17 00:00:00 2001
From: Luiz Otavio O Souza <loos@FreeBSD.org>
Date: Mon, 3 Oct 2016 19:48:56 +0000
Subject: [PATCH] Enable the TX completion interrupt for the cpsw NIC to assure
 the free tx descriptors are reclaimed as soon as possible.

Without this the free buffers are reclaimed only on watchdog runs or after
trying to enqueue more packets.

Sponsored by:	Rubicon Communications, LLC (Netgte)
---
 sys/arm/ti/cpsw/if_cpsw.c | 48 ++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 16 deletions(-)

diff --git a/sys/arm/ti/cpsw/if_cpsw.c b/sys/arm/ti/cpsw/if_cpsw.c
index e3da058703f..783bedecfae 100644
--- a/sys/arm/ti/cpsw/if_cpsw.c
+++ b/sys/arm/ti/cpsw/if_cpsw.c
@@ -117,6 +117,7 @@ static void cpsw_intr_rx(void *arg);
 static struct mbuf *cpsw_rx_dequeue(struct cpsw_softc *);
 static void cpsw_rx_enqueue(struct cpsw_softc *);
 static void cpswp_start(struct ifnet *);
+static void cpsw_intr_tx(void *);
 static void cpswp_tx_enqueue(struct cpswp_softc *);
 static int cpsw_tx_dequeue(struct cpsw_softc *);
 
@@ -209,6 +210,15 @@ static struct resource_spec irq_res_spec[] = {
 	{ -1, 0 }
 };
 
+static struct {
+	void (*cb)(void *);
+} cpsw_intr_cb[] = {
+	{ cpsw_intr_rx_thresh },
+	{ cpsw_intr_rx },
+	{ cpsw_intr_tx },
+	{ cpsw_intr_misc },
+};
+
 /* Number of entries here must match size of stats
  * array in struct cpswp_softc. */
 static struct cpsw_stat {
@@ -590,13 +600,15 @@ cpsw_init(struct cpsw_softc *sc)
 	/* Enable Interrupts for core 0 */
 	cpsw_write_4(sc, CPSW_WR_C_RX_THRESH_EN(0), 0xFF);
 	cpsw_write_4(sc, CPSW_WR_C_RX_EN(0), 0xFF);
+	cpsw_write_4(sc, CPSW_WR_C_TX_EN(0), 0xFF);
 	cpsw_write_4(sc, CPSW_WR_C_MISC_EN(0), 0x1F);
 
 	/* Enable host Error Interrupt */
 	cpsw_write_4(sc, CPSW_CPDMA_DMA_INTMASK_SET, 3);
 
-	/* Enable interrupts for RX Channel 0 */
+	/* Enable interrupts for RX and TX on Channel 0 */
 	cpsw_write_4(sc, CPSW_CPDMA_RX_INTMASK_SET, 1);
+	cpsw_write_4(sc, CPSW_CPDMA_TX_INTMASK_SET, 1);
 
 	/* Initialze MDIO - ENABLE, PREAMBLE=0, FAULTENB, CLKDIV=0xFF */
 	/* TODO Calculate MDCLK=CLK/(CLKDIV+1) */
@@ -645,22 +657,14 @@ cpsw_probe(device_t dev)
 static int
 cpsw_intr_attach(struct cpsw_softc *sc)
 {
+	int i;
 
-	/* Note: We don't use sc->irq_res[2] (TX interrupt) */
-	if (bus_setup_intr(sc->dev, sc->irq_res[0],
-	    INTR_TYPE_NET | INTR_MPSAFE, NULL, cpsw_intr_rx_thresh,
-	    sc, &sc->ih_cookie[0]) != 0) {
-		return (-1);
-	}
-	if (bus_setup_intr(sc->dev, sc->irq_res[1],
-	    INTR_TYPE_NET | INTR_MPSAFE, NULL, cpsw_intr_rx,
-	    sc, &sc->ih_cookie[1]) != 0) {
-		return (-1);
-	}
-	if (bus_setup_intr(sc->dev, sc->irq_res[3],
-	    INTR_TYPE_NET | INTR_MPSAFE, NULL, cpsw_intr_misc,
-	    sc, &sc->ih_cookie[3]) != 0) {
-		return (-1);
+	for (i = 0; i < CPSW_INTR_COUNT; i++) {
+		if (bus_setup_intr(sc->dev, sc->irq_res[i],
+		    INTR_TYPE_NET | INTR_MPSAFE, NULL,
+		    cpsw_intr_cb[i].cb, sc, &sc->ih_cookie[i]) != 0) {
+			return (-1);
+		}
 	}
 
 	return (0);
@@ -1695,6 +1699,18 @@ cpswp_start(struct ifnet *ifp)
 	CPSW_TX_UNLOCK(sc->swsc);
 }
 
+static void
+cpsw_intr_tx(void *arg)
+{
+	struct cpsw_softc *sc;
+
+	sc = (struct cpsw_softc *)arg;
+	CPSW_TX_LOCK(sc);
+	cpsw_tx_dequeue(sc);
+	cpsw_write_4(sc, CPSW_CPDMA_CPDMA_EOI_VECTOR, 2);
+	CPSW_TX_UNLOCK(sc);
+}
+
 static void
 cpswp_tx_enqueue(struct cpswp_softc *sc)
 {