diff options
Diffstat (limited to 'sys/dev/ath/if_ath.c')
| -rw-r--r-- | sys/dev/ath/if_ath.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/sys/dev/ath/if_ath.c b/sys/dev/ath/if_ath.c index 4f37be2..c968179 100644 --- a/sys/dev/ath/if_ath.c +++ b/sys/dev/ath/if_ath.c @@ -1544,9 +1544,23 @@ ath_rxbuf_init(struct ath_softc *sc, struct ath_buf *bf) } bus_dmamap_sync(sc->sc_dmat, bf->bf_dmamap, BUS_DMASYNC_PREREAD); - /* setup descriptors */ + /* + * Setup descriptors. For receive we always terminate + * the descriptor list with a self-linked entry so we'll + * not get overrun under high load (as can happen with a + * 5212 when ANI processing enables PHY errors). + * + * To insure the last descriptor is self-linked we create + * each descriptor as self-linked and add it to the end. As + * each additional descriptor is added the previous self-linked + * entry is ``fixed'' naturally. This should be safe even + * if DMA is happening. When processing RX interrupts we + * never remove/process the last, self-linked, entry on the + * descriptor list. This insures the hardware always has + * someplace to write a new frame. + */ ds = bf->bf_desc; - ds->ds_link = 0; + ds->ds_link = bf->bf_daddr; /* link to self */ ds->ds_data = bf->bf_segs[0].ds_addr; ath_hal_setuprxdesc(ah, ds , m->m_len /* buffer size */ @@ -1584,12 +1598,16 @@ ath_rx_proc(void *arg, int npending) if_printf(ifp, "ath_rx_proc: no buffer!\n"); break; } + ds = bf->bf_desc; + if (ds->ds_link == bf->bf_daddr) { + /* NB: never process the self-linked entry at the end */ + break; + } m = bf->bf_m; if (m == NULL) { /* NB: shouldn't happen */ if_printf(ifp, "ath_rx_proc: no mbuf!\n"); continue; } - ds = bf->bf_desc; status = ath_hal_rxprocdesc(ah, ds); #ifdef AR_DEBUG if (ath_debug > 1) |
