[rtems-libbsd commit] if_dwc: Avoid tx defrag if possible
Sebastian Huber
sebh at rtems.org
Tue Jan 10 10:06:12 UTC 2017
Module: rtems-libbsd
Branch: master
Commit: 5deeb69c7ee3bcca615128487092346ea0da19ef
Changeset: http://git.rtems.org/rtems-libbsd/commit/?id=5deeb69c7ee3bcca615128487092346ea0da19ef
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Fri Mar 27 14:16:40 2015 +0100
if_dwc: Avoid tx defrag if possible
Drop packets in case of resource shortage.
---
freebsd/sys/dev/dwc/if_dwc.c | 143 ++++++++++++++++++++++++----------------
freebsd/sys/dev/dwc/if_dwcvar.h | 1 +
2 files changed, 89 insertions(+), 55 deletions(-)
diff --git a/freebsd/sys/dev/dwc/if_dwc.c b/freebsd/sys/dev/dwc/if_dwc.c
index f7e9775..e3ae559 100644
--- a/freebsd/sys/dev/dwc/if_dwc.c
+++ b/freebsd/sys/dev/dwc/if_dwc.c
@@ -157,10 +157,10 @@ next_rxidx(struct dwc_softc *sc, uint32_t curidx)
}
static inline uint32_t
-next_txidx(struct dwc_softc *sc, uint32_t curidx)
+next_txidx(struct dwc_softc *sc, uint32_t curidx, int inc)
{
- return ((curidx + 1) % TX_DESC_COUNT);
+ return ((curidx + (uint32_t)inc) % TX_DESC_COUNT);
}
static void
@@ -172,62 +172,100 @@ dwc_get1paddr(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
*(bus_addr_t *)arg = segs[0].ds_addr;
}
-inline static uint32_t
-dwc_setup_txdesc(struct dwc_softc *sc, int idx, bus_addr_t paddr,
- uint32_t len)
+static void
+dwc_setup_txdesc(struct dwc_softc *sc, int idx, bus_dma_segment_t segs[TX_MAX_DMA_SEGS],
+ int nsegs)
{
- uint32_t flags;
+ int i;
- ++sc->txcount;
+ sc->txcount += nsegs;
- sc->txdesc_ring[idx].addr = (uint32_t)(paddr);
- if (sc->mactype == DWC_GMAC_ALT_DESC) {
- flags = DDESC_CNTL_TXCHAIN | DDESC_CNTL_TXFIRST
- | DDESC_CNTL_TXLAST | DDESC_CNTL_TXINT;
- sc->txdesc_ring[idx].tdes0 = 0;
- sc->txdesc_ring[idx].tdes1 = flags | len;
- } else {
- flags = DDESC_TDES0_TXCHAIN | DDESC_TDES0_TXFIRST
- | DDESC_TDES0_TXLAST | DDESC_TDES0_TXINT;
- sc->txdesc_ring[idx].tdes0 = flags;
- sc->txdesc_ring[idx].tdes1 = len;
- }
- wmb();
+ idx = next_txidx(sc, idx, nsegs);
+ sc->tx_idx_head = idx;
- sc->txdesc_ring[idx].tdes0 = DDESC_TDES0_TXCHAIN | DDESC_TDES0_TXFIRST
- | DDESC_TDES0_TXLAST | DDESC_TDES0_TXINT | DDESC_TDES0_OWN;
- wmb();
+ /*
+ * Fill in the TX descriptors back to front so that OWN bit in first
+ * descriptor is set last.
+ */
+ for (i = nsegs - 1; i >= 0; i--) {
+ uint32_t flags;
+ uint32_t len;
+
+ idx = next_txidx(sc, idx, -1);
+
+ sc->txdesc_ring[idx].addr = segs[i].ds_addr;
+ len = segs[i].ds_len;
+
+ if (sc->mactype == DWC_GMAC_ALT_DESC) {
+ flags = DDESC_CNTL_TXCHAIN | DDESC_CNTL_TXINT;
+
+ if (i == 0)
+ flags |= DDESC_CNTL_TXFIRST;
+
+ if (i == nsegs - 1)
+ flags |= DDESC_CNTL_TXLAST;
+
+ sc->txdesc_ring[idx].tdes0 = 0;
+ sc->txdesc_ring[idx].tdes1 = flags | len;
+ } else {
+ flags = DDESC_TDES0_TXCHAIN | DDESC_TDES0_TXINT |
+ DDESC_TDES0_OWN;
+
+ if (i == 0)
+ flags |= DDESC_TDES0_TXFIRST;
+
+ if (i == nsegs - 1)
+ flags |= DDESC_TDES0_TXLAST;
+
+ sc->txdesc_ring[idx].tdes1 = len;
+ wmb();
+ sc->txdesc_ring[idx].tdes0 = flags;
+ }
- return (next_txidx(sc, idx));
+ wmb();
+
+ if (i != 0)
+ sc->txbuf_map[idx].mbuf = NULL;
+ }
}
-static int
-dwc_setup_txbuf(struct dwc_softc *sc, int idx, struct mbuf **mp)
+static void
+dwc_setup_txbuf(struct dwc_softc *sc, struct mbuf *m, int *start_tx)
{
- struct bus_dma_segment seg;
- int error, nsegs;
- struct mbuf * m;
-
- if ((m = m_defrag(*mp, M_NOWAIT)) == NULL)
- return (ENOMEM);
- *mp = m;
+ bus_dma_segment_t segs[TX_MAX_DMA_SEGS];
+ int error, nsegs, idx;
+ idx = sc->tx_idx_head;
error = bus_dmamap_load_mbuf_sg(sc->txbuf_tag, sc->txbuf_map[idx].map,
- m, &seg, &nsegs, 0);
+ m, &seg, &nsegs, BUS_DMA_NOWAIT);
+
+ if (error == EFBIG) {
+ /* Too many segments! Defrag and try again. */
+ struct mbuf *m2 = m_defrag(m, M_NOWAIT);
+
+ if (m2 == NULL) {
+ m_freem(m);
+ return;
+ }
+ m = m2;
+ error = bus_dmamap_load_mbuf_sg(sc->txbuf_tag,
+ sc->txbuf_map[idx].map, m, &seg, &nsegs, BUS_DMA_NOWAIT);
+ }
if (error != 0) {
- return (ENOMEM);
+ /* Give up. */
+ m_freem(m);
+ return;
}
- KASSERT(nsegs == 1, ("%s: %d segments returned!", __func__, nsegs));
+ sc->txbuf_map[idx].mbuf = m;
bus_dmamap_sync(sc->txbuf_tag, sc->txbuf_map[idx].map,
BUS_DMASYNC_PREWRITE);
- sc->txbuf_map[idx].mbuf = m;
-
- dwc_setup_txdesc(sc, idx, seg.ds_addr, seg.ds_len);
+ dwc_setup_txdesc(sc, idx, segs, nsegs);
- return (0);
+ ETHER_BPF_MTAP(sc->ifp, m);
+ *start_tx = 1;
}
static void
@@ -235,7 +273,7 @@ dwc_txstart_locked(struct dwc_softc *sc)
{
struct ifnet *ifp;
struct mbuf *m;
- int enqueued;
+ int start_tx;
DWC_ASSERT_LOCKED(sc);
@@ -244,10 +282,10 @@ dwc_txstart_locked(struct dwc_softc *sc)
ifp = sc->ifp;
- enqueued = 0;
+ start_tx = 0;
for (;;) {
- if (sc->txcount == (TX_DESC_COUNT-1)) {
+ if (sc->txcount >= (TX_DESC_COUNT - 1 - TX_MAX_DMA_SEGS)) {
ifp->if_drv_flags |= IFF_DRV_OACTIVE;
break;
}
@@ -255,16 +293,11 @@ dwc_txstart_locked(struct dwc_softc *sc)
IFQ_DRV_DEQUEUE(&ifp->if_snd, m);
if (m == NULL)
break;
- if (dwc_setup_txbuf(sc, sc->tx_idx_head, &m) != 0) {
- IFQ_DRV_PREPEND(&ifp->if_snd, m);
- break;
- }
- BPF_MTAP(ifp, m);
- sc->tx_idx_head = next_txidx(sc, sc->tx_idx_head);
- ++enqueued;
+
+ dwc_setup_txbuf(sc, m, &start_tx);
}
- if (enqueued != 0) {
+ if (start_tx != 0) {
WRITE4(sc, TRANSMIT_POLL_DEMAND, 0x1);
sc->tx_watchdog_count = WATCHDOG_TIMEOUT_SECS;
}
@@ -475,7 +508,7 @@ dwc_setup_rxdesc(struct dwc_softc *sc, int idx, bus_addr_t paddr)
static int
dwc_setup_rxbuf(struct dwc_softc *sc, int idx, struct mbuf *m)
{
- struct bus_dma_segment seg;
+ bus_dma_segment_t seg;
int error, nsegs;
m_adj(m, ETHER_ALIGN);
@@ -717,7 +750,7 @@ dwc_txfinish_locked(struct dwc_softc *sc)
m_freem(bmap->mbuf);
bmap->mbuf = NULL;
--sc->txcount;
- sc->tx_idx_tail = next_txidx(sc, sc->tx_idx_tail);
+ sc->tx_idx_tail = next_txidx(sc, sc->tx_idx_tail, 1);
}
sc->ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
@@ -876,7 +909,7 @@ setup_dma(struct dwc_softc *sc)
sc->txdesc_ring[idx].tdes0 = DDESC_TDES0_TXCHAIN;
sc->txdesc_ring[idx].tdes1 = 0;
}
- nidx = next_txidx(sc, idx);
+ nidx = next_txidx(sc, idx, 1);
sc->txdesc_ring[idx].addr_next = sc->txdesc_ring_paddr +
(nidx * sizeof(struct dwc_hwdesc));
}
@@ -887,7 +920,7 @@ setup_dma(struct dwc_softc *sc)
BUS_SPACE_MAXADDR_32BIT, /* lowaddr */
BUS_SPACE_MAXADDR, /* highaddr */
NULL, NULL, /* filter, filterarg */
- MCLBYTES, 1, /* maxsize, nsegments */
+ MCLBYTES, TX_MAX_DMA_SEGS, /* maxsize, nsegments */
MCLBYTES, /* maxsegsize */
0, /* flags */
NULL, NULL, /* lockfunc, lockarg */
diff --git a/freebsd/sys/dev/dwc/if_dwcvar.h b/freebsd/sys/dev/dwc/if_dwcvar.h
index d9198bd..d832f1a 100644
--- a/freebsd/sys/dev/dwc/if_dwcvar.h
+++ b/freebsd/sys/dev/dwc/if_dwcvar.h
@@ -49,6 +49,7 @@
#define RX_DESC_SIZE (sizeof(struct dwc_hwdesc) * RX_DESC_COUNT)
#define TX_DESC_COUNT 1024
#define TX_DESC_SIZE (sizeof(struct dwc_hwdesc) * TX_DESC_COUNT)
+#define TX_MAX_DMA_SEGS 8 /* maximum segs in a tx mbuf dma */
struct dwc_bufmap {
bus_dmamap_t map;
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