Add an option to allow the minimum number of delimiters to be tweaked.

This is primarily for debugging purposes.

Tested:

* AR5416, STA mode

4 files changed, 18 insertions, 2 deletions

diff --git a/sys/dev/ath/if_ath.c b/sys/dev/ath/if_ath.c
index 4388399..98c219bb 100644
--- a/sys/dev/ath/if_ath.c
+++ b/sys/dev/ath/if_ath.c
@@ -800,6 +800,7 @@ ath_attach(u_int16_t devid, struct ath_softc *sc)
 	sc->sc_tid_hwq_lo = ATH_AGGR_SCHED_LOW;
 	sc->sc_tid_hwq_hi = ATH_AGGR_SCHED_HIGH;
 	sc->sc_aggr_limit = ATH_AGGR_MAXSIZE;
+	sc->sc_delim_min_pad = 0;
 
 	/*
 	 * Check if the hardware requires PCI register serialisation.
diff --git a/sys/dev/ath/if_ath_sysctl.c b/sys/dev/ath/if_ath_sysctl.c
index bce4ee6..bbd1fe8 100644
--- a/sys/dev/ath/if_ath_sysctl.c
+++ b/sys/dev/ath/if_ath_sysctl.c
@@ -714,9 +714,16 @@ ath_sysctlattach(struct ath_softc *sc)
 
 	/* Aggregate length twiddles */
 	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
-		"aggr_limit", CTLFLAG_RW, &sc->sc_aggr_limit, 0, "");
+		"aggr_limit", CTLFLAG_RW, &sc->sc_aggr_limit, 0,
+		"Maximum A-MPDU size, or 0 for 'default'");
 	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
-		"rts_aggr_limit", CTLFLAG_RW, &sc->sc_rts_aggr_limit, 0, "");
+		"rts_aggr_limit", CTLFLAG_RW, &sc->sc_rts_aggr_limit, 0,
+		"Maximum A-MPDU size for RTS-protected frames, or '0' "
+		"for default");
+	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
+		"delim_min_pad", CTLFLAG_RW, &sc->sc_delim_min_pad, 0,
+		"Enforce a minimum number of delimiters per A-MPDU "
+		" sub-frame");
 
 	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
 		"txq_data_minfree", CTLFLAG_RW, &sc->sc_txq_data_minfree,
diff --git a/sys/dev/ath/if_ath_tx_ht.c b/sys/dev/ath/if_ath_tx_ht.c
index 022a00a..7245d06 100644
--- a/sys/dev/ath/if_ath_tx_ht.c
+++ b/sys/dev/ath/if_ath_tx_ht.c
@@ -364,6 +364,13 @@ ath_compute_num_delims(struct ath_softc *sc, struct ath_buf *first_bf,
 	    && ndelim < AH_FIRST_DESC_NDELIMS)
 		ndelim = AH_FIRST_DESC_NDELIMS;
 
+	/*
+	 * If sc_delim_min_pad is non-zero, enforce it as the minimum
+	 * pad delimiter count.
+	 */
+	if (sc->sc_delim_min_pad != 0)
+		ndelim = MAX(ndelim, sc->sc_delim_min_pad);
+
 	DPRINTF(sc, ATH_DEBUG_SW_TX_AGGR,
 	    "%s: pktlen=%d, ndelim=%d, mpdudensity=%d\n",
 	    __func__, pktlen, ndelim, mpdudensity);
diff --git a/sys/dev/ath/if_athvar.h b/sys/dev/ath/if_athvar.h
index 09d03bc..1b6e160 100644
--- a/sys/dev/ath/if_athvar.h
+++ b/sys/dev/ath/if_athvar.h
@@ -719,6 +719,7 @@ struct ath_softc {
 	int			sc_rxchainmask;	/* currently configured RX chainmask */
 	int			sc_rts_aggr_limit;	/* TX limit on RTS aggregates */
 	int			sc_aggr_limit;	/* TX limit on all aggregates */
+	int			sc_delim_min_pad;	/* Minimum delimiter count */
 
 	/* Queue limits */