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if_awg: store mbuf and dma mapping in the last segment of a tx frame instead of the first

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According to the datasheet, TX_DESC_CTL is cleared when whole frame is transmitted or all
data in the current descriptor's buffer are transmitted.
When the mbuf and mapping are stored in the first segment and in a scenario where a tx
completion interrupt arrives for a frame and only the start of the next frame was transmitted,
at the time of interrupt processing the mbuf and mapping will be freed when processing the
first segment of the next frame but the other untrasmitted segments still need to use them.

Submitted by:	Guy Yur <guyyur@gmail.com>
Differential Revision:	https://reviews.freebsd.org/D13031
This commit is contained in:
Emmanuel Vadot 2017-11-18 20:46:31 +00:00
parent c6110e7514
commit fce9d29f8d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=325979
1 changed files with 13 additions and 8 deletions
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21
sys/arm/allwinner/if_awg.c
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@ -390,17 +390,19 @@ awg_media_change(if_t ifp)
static int
awg_setup_txbuf(struct awg_softc *sc, int index, struct mbuf **mp)
{
bus_dmamap_t map;
bus_dma_segment_t segs[TX_MAX_SEGS];
int error, nsegs, cur, first, i;
int error, nsegs, cur, first, last, i;
u_int csum_flags;
uint32_t flags, status;
struct mbuf *m;
cur = first = index;
map = sc->tx.buf_map[first].map;
m = *mp;
error = bus_dmamap_load_mbuf_sg(sc->tx.buf_tag,
sc->tx.buf_map[index].map, m, segs, &nsegs, BUS_DMA_NOWAIT);
error = bus_dmamap_load_mbuf_sg(sc->tx.buf_tag, map, m, segs,
&nsegs, BUS_DMA_NOWAIT);
if (error == EFBIG) {
m = m_collapse(m, M_NOWAIT, TX_MAX_SEGS);
if (m == NULL) {
@ -408,16 +410,15 @@ awg_setup_txbuf(struct awg_softc *sc, int index, struct mbuf **mp)
return (0);
}
*mp = m;
error = bus_dmamap_load_mbuf_sg(sc->tx.buf_tag,
sc->tx.buf_map[index].map, m, segs, &nsegs, BUS_DMA_NOWAIT);
error = bus_dmamap_load_mbuf_sg(sc->tx.buf_tag, map, m,
segs, &nsegs, BUS_DMA_NOWAIT);
}
if (error != 0) {
device_printf(sc->dev, "awg_setup_txbuf: bus_dmamap_load_mbuf_sg failed\n");
return (0);
}
bus_dmamap_sync(sc->tx.buf_tag, sc->tx.buf_map[index].map,
BUS_DMASYNC_PREWRITE);
bus_dmamap_sync(sc->tx.buf_tag, map, BUS_DMASYNC_PREWRITE);
flags = TX_FIR_DESC;
status = 0;
@ -458,7 +459,11 @@ awg_setup_txbuf(struct awg_softc *sc, int index, struct mbuf **mp)
cur = TX_NEXT(cur);
}
sc->tx.buf_map[first].mbuf = m;
/* Store mapping and mbuf in the last segment */
last = TX_SKIP(cur, TX_DESC_COUNT - 1);
sc->tx.buf_map[first].map = sc->tx.buf_map[last].map;
sc->tx.buf_map[last].map = map;
sc->tx.buf_map[last].mbuf = m;
/*
* The whole mbuf chain has been DMA mapped,