Add the 'nomimo' nwflag which disables MIMO in 11n mode.

This flag restricts a wireless driver to MCS0 - MCS7 for both transmission
and reception. It can be set to work around packet loss in 11n mode caused
by unused antenna connectors on a MIMO-capable wireless network device.

man page tweak from tracey@
ok deraadt@

4 files changed, 93 insertions, 50 deletions

diff --git a/sys/dev/ic/athn.c b/sys/dev/ic/athn.c
index 0683a8802b2..40725b02c43 100644
--- a/sys/dev/ic/athn.c
+++ b/sys/dev/ic/athn.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: athn.c,v 1.106 2020/04/28 06:58:09 stsp Exp $	*/
+/*	$OpenBSD: athn.c,v 1.107 2020/04/29 13:13:29 stsp Exp $	*/
 
 /*-
  * Copyright (c) 2009 Damien Bergamini <damien.bergamini@free.fr>
@@ -180,6 +180,53 @@ struct cfdriver athn_cd = {
 	NULL, "athn", DV_IFNET
 };
 
+void
+athn_config_ht(struct athn_softc *sc)
+{
+	struct ieee80211com *ic = &sc->sc_ic;
+	int i, ntxstreams, nrxstreams;
+
+	if ((sc->flags & ATHN_FLAG_11N) == 0)
+		return;
+
+	/* Set HT capabilities. */
+	ic->ic_htcaps = (IEEE80211_HTCAP_SMPS_DIS <<
+	    IEEE80211_HTCAP_SMPS_SHIFT);
+#ifdef notyet
+	ic->ic_htcaps |= IEEE80211_HTCAP_CBW20_40 |
+	    IEEE80211_HTCAP_SGI40 |
+	    IEEE80211_HTCAP_DSSSCCK40;
+#endif
+	ic->ic_htxcaps = 0;
+#ifdef notyet
+	if (AR_SREV_9271(sc) || AR_SREV_9287_10_OR_LATER(sc))
+		ic->ic_htcaps |= IEEE80211_HTCAP_SGI20;
+	if (AR_SREV_9380_10_OR_LATER(sc))
+		ic->ic_htcaps |= IEEE80211_HTCAP_LDPC;
+	if (AR_SREV_9280_10_OR_LATER(sc)) {
+		ic->ic_htcaps |= IEEE80211_HTCAP_TXSTBC;
+		ic->ic_htcaps |= 1 << IEEE80211_HTCAP_RXSTBC_SHIFT;
+	}
+#endif
+	ntxstreams = sc->ntxchains;
+	nrxstreams = sc->nrxchains;
+	if (!AR_SREV_9380_10_OR_LATER(sc)) {
+		ntxstreams = MIN(ntxstreams, 2);
+		nrxstreams = MIN(nrxstreams, 2);
+	}
+	/* Set supported HT rates. */
+	if (ic->ic_userflags & IEEE80211_F_NOMIMO)
+		ntxstreams = nrxstreams = 1;
+	memset(ic->ic_sup_mcs, 0, sizeof(ic->ic_sup_mcs));
+	for (i = 0; i < nrxstreams; i++)
+		ic->ic_sup_mcs[i] = 0xff;
+	ic->ic_tx_mcs_set = IEEE80211_TX_MCS_SET_DEFINED;
+	if (ntxstreams != nrxstreams) {
+		ic->ic_tx_mcs_set |= IEEE80211_TX_RX_MCS_NOT_EQUAL;
+		ic->ic_tx_mcs_set |= (ntxstreams - 1) << 2;
+	}
+}
+
 int
 athn_attach(struct athn_softc *sc)
 {
@@ -302,43 +349,7 @@ athn_attach(struct athn_softc *sc)
 	    IEEE80211_C_SHPREAMBLE |	/* Short preamble supported. */
 	    IEEE80211_C_PMGT;		/* Power saving supported. */
 
-	if (sc->flags & ATHN_FLAG_11N) {
-		int i, ntxstreams, nrxstreams;
-
-		/* Set HT capabilities. */
-		ic->ic_htcaps = (IEEE80211_HTCAP_SMPS_DIS <<
-		    IEEE80211_HTCAP_SMPS_SHIFT);
-#ifdef notyet
-		ic->ic_htcaps |= IEEE80211_HTCAP_CBW20_40 |
-		    IEEE80211_HTCAP_SGI40 |
-		    IEEE80211_HTCAP_DSSSCCK40;
-#endif
-		ic->ic_htxcaps = 0;
-#ifdef notyet
-		if (AR_SREV_9271(sc) || AR_SREV_9287_10_OR_LATER(sc))
-			ic->ic_htcaps |= IEEE80211_HTCAP_SGI20;
-		if (AR_SREV_9380_10_OR_LATER(sc))
-			ic->ic_htcaps |= IEEE80211_HTCAP_LDPC;
-		if (AR_SREV_9280_10_OR_LATER(sc)) {
-			ic->ic_htcaps |= IEEE80211_HTCAP_TXSTBC;
-			ic->ic_htcaps |= 1 << IEEE80211_HTCAP_RXSTBC_SHIFT;
-		}
-#endif
-		ntxstreams = sc->ntxchains;
-		nrxstreams = sc->nrxchains;
-		if (!AR_SREV_9380_10_OR_LATER(sc)) {
-			ntxstreams = MIN(ntxstreams, 2);
-			nrxstreams = MIN(nrxstreams, 2);
-		}
-		/* Set supported HT rates. */
-		for (i = 0; i < nrxstreams; i++)
-			ic->ic_sup_mcs[i] = 0xff;
-		ic->ic_tx_mcs_set |= IEEE80211_TX_MCS_SET_DEFINED;
-		if (ntxstreams != nrxstreams) {
-			ic->ic_tx_mcs_set |= IEEE80211_TX_RX_MCS_NOT_EQUAL;
-			ic->ic_tx_mcs_set |= (ntxstreams - 1) << 2;
-		}
-	}
+	athn_config_ht(sc);
 
 	/* Set supported rates. */
 	if (sc->flags & ATHN_FLAG_11G) {
@@ -3070,6 +3081,8 @@ athn_init(struct ifnet *ifp)
 		goto fail;
 	}
 
+	athn_config_ht(sc);
+
 	/* Enable Rx. */
 	athn_rx_start(sc);
 
diff --git a/sys/dev/pci/if_iwm.c b/sys/dev/pci/if_iwm.c
index 01c059a512b..906e910b02a 100644
--- a/sys/dev/pci/if_iwm.c
+++ b/sys/dev/pci/if_iwm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwm.c,v 1.307 2020/04/09 21:36:50 stsp Exp $	*/
+/*	$OpenBSD: if_iwm.c,v 1.308 2020/04/29 13:13:30 stsp Exp $	*/
 
 /*
  * Copyright (c) 2014, 2016 genua gmbh <info@genua.de>
@@ -324,6 +324,7 @@ int	iwm_nvm_read_section(struct iwm_softc *, uint16_t, uint8_t *,
 	    uint16_t *, size_t);
 void	iwm_init_channel_map(struct iwm_softc *, const uint16_t * const,
 	    const uint8_t *nvm_channels, int nchan);
+int	iwm_mimo_enabled(struct iwm_softc *);
 void	iwm_setup_ht_rates(struct iwm_softc *);
 void	iwm_htprot_task(void *);
 void	iwm_update_htprot(struct ieee80211com *, struct ieee80211_node *);
@@ -2861,6 +2862,15 @@ iwm_init_channel_map(struct iwm_softc *sc, const uint16_t * const nvm_ch_flags,
 	}
 }
 
+int
+iwm_mimo_enabled(struct iwm_softc *sc)
+{
+	struct ieee80211com *ic = &sc->sc_ic;
+
+	return !sc->sc_nvm.sku_cap_mimo_disable &&
+	    (ic->ic_userflags & IEEE80211_F_NOMIMO) == 0;
+}
+
 void
 iwm_setup_ht_rates(struct iwm_softc *sc)
 {
@@ -2870,9 +2880,10 @@ iwm_setup_ht_rates(struct iwm_softc *sc)
 	/* TX is supported with the same MCS as RX. */
 	ic->ic_tx_mcs_set = IEEE80211_TX_MCS_SET_DEFINED;
 
+	memset(ic->ic_sup_mcs, 0, sizeof(ic->ic_sup_mcs));
 	ic->ic_sup_mcs[0] = 0xff;		/* MCS 0-7 */
 
-	if (sc->sc_nvm.sku_cap_mimo_disable)
+	if (!iwm_mimo_enabled(sc))
 		return;
 
 	rx_ant = iwm_fw_valid_rx_ant(sc);
@@ -5245,7 +5256,7 @@ iwm_add_sta_cmd(struct iwm_softc *sc, struct iwm_node *in, int update)
 		    |= htole32(IWM_STA_FLG_MAX_AGG_SIZE_MSK |
 		    IWM_STA_FLG_AGG_MPDU_DENS_MSK);
 
-		if (!sc->sc_nvm.sku_cap_mimo_disable) {
+		if (iwm_mimo_enabled(sc)) {
 			if (in->in_ni.ni_rxmcs[1] != 0) {
 				add_sta_cmd.station_flags |=
 				    htole32(IWM_STA_FLG_MIMO_EN_MIMO2);
@@ -6629,7 +6640,7 @@ iwm_run(struct iwm_softc *sc)
 	/* Configure Rx chains for MIMO. */
 	if ((ic->ic_opmode == IEEE80211_M_MONITOR ||
 	    (in->in_ni.ni_flags & IEEE80211_NODE_HT)) &&
-	    !sc->sc_nvm.sku_cap_mimo_disable) {
+	    iwm_mimo_enabled(sc)) {
 		err = iwm_phy_ctxt_cmd(sc, &sc->sc_phyctxt[0],
 		    2, 2, IWM_FW_CTXT_ACTION_MODIFY, 0);
 		if (err) {
@@ -6755,7 +6766,7 @@ iwm_run_stop(struct iwm_softc *sc)
 
 	/* Reset Tx chains in case MIMO was enabled. */
 	if ((in->in_ni.ni_flags & IEEE80211_NODE_HT) &&
-	    !sc->sc_nvm.sku_cap_mimo_disable) {
+	    iwm_mimo_enabled(sc)) {
 		err = iwm_phy_ctxt_cmd(sc, &sc->sc_phyctxt[0], 1, 1,
 		    IWM_FW_CTXT_ACTION_MODIFY, 0);
 		if (err) {
@@ -7727,6 +7738,9 @@ iwm_init(struct ifnet *ifp)
 		return err;
 	}
 
+	if (sc->sc_nvm.sku_cap_11n_enable)
+		iwm_setup_ht_rates(sc);
+
 	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_flags |= IFF_RUNNING;
 
diff --git a/sys/dev/pci/if_iwx.c b/sys/dev/pci/if_iwx.c
index 27973d75877..64c3641a2d0 100644
--- a/sys/dev/pci/if_iwx.c
+++ b/sys/dev/pci/if_iwx.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwx.c,v 1.10 2020/04/03 08:32:21 stsp Exp $	*/
+/*	$OpenBSD: if_iwx.c,v 1.11 2020/04/29 13:13:30 stsp Exp $	*/
 
 /*
  * Copyright (c) 2014, 2016 genua gmbh <info@genua.de>
@@ -294,6 +294,7 @@ int	iwx_nvm_read_section(struct iwx_softc *, uint16_t, uint8_t *,
 void	iwx_init_channel_map(struct iwx_softc *, const uint16_t * const,
 	    const uint8_t *nvm_channels, int nchan);
 void	iwx_setup_ht_rates(struct iwx_softc *);
+int	iwx_mimo_enabled(struct iwx_softc *);
 void	iwx_htprot_task(void *);
 void	iwx_update_htprot(struct ieee80211com *, struct ieee80211_node *);
 int	iwx_ampdu_rx_start(struct ieee80211com *, struct ieee80211_node *,
@@ -2709,6 +2710,15 @@ iwx_init_channel_map(struct iwx_softc *sc, const uint16_t * const nvm_ch_flags,
 	}
 }
 
+int
+iwx_mimo_enabled(struct iwx_softc *sc)
+{
+	struct ieee80211com *ic = &sc->sc_ic;
+
+	return !sc->sc_nvm.sku_cap_mimo_disable &&
+	    (ic->ic_userflags & IEEE80211_F_NOMIMO) == 0;
+}
+
 void
 iwx_setup_ht_rates(struct iwx_softc *sc)
 {
@@ -2718,9 +2728,10 @@ iwx_setup_ht_rates(struct iwx_softc *sc)
 	/* TX is supported with the same MCS as RX. */
 	ic->ic_tx_mcs_set = IEEE80211_TX_MCS_SET_DEFINED;
 
+	memset(ic->ic_sup_mcs, 0, sizeof(ic->ic_sup_mcs));
 	ic->ic_sup_mcs[0] = 0xff;		/* MCS 0-7 */
 
-	if (sc->sc_nvm.sku_cap_mimo_disable)
+	if (!iwx_mimo_enabled(sc))
 		return;
 
 	rx_ant = iwx_fw_valid_rx_ant(sc);
@@ -5751,7 +5762,7 @@ iwx_run(struct iwx_softc *sc)
 	/* Configure Rx chains for MIMO. */
 	if ((ic->ic_opmode == IEEE80211_M_MONITOR ||
 	    (in->in_ni.ni_flags & IEEE80211_NODE_HT)) &&
-	    !sc->sc_nvm.sku_cap_mimo_disable) {
+	    iwx_mimo_enabled(sc)) {
 		err = iwx_phy_ctxt_cmd(sc, &sc->sc_phyctxt[0],
 		    2, 2, IWX_FW_CTXT_ACTION_MODIFY, 0);
 		if (err) {
@@ -5872,7 +5883,7 @@ iwx_run_stop(struct iwx_softc *sc)
 
 	/* Reset Tx chains in case MIMO was enabled. */
 	if ((in->in_ni.ni_flags & IEEE80211_NODE_HT) &&
-	    !sc->sc_nvm.sku_cap_mimo_disable) {
+	    iwx_mimo_enabled(sc)) {
 		err = iwx_phy_ctxt_cmd(sc, &sc->sc_phyctxt[0], 1, 1,
 		    IWX_FW_CTXT_ACTION_MODIFY, 0);
 		if (err) {
@@ -6430,6 +6441,9 @@ iwx_init(struct ifnet *ifp)
 		return err;
 	}
 
+	if (sc->sc_nvm.sku_cap_11n_enable)
+		iwx_setup_ht_rates(sc);
+
 	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_flags |= IFF_RUNNING;
 
diff --git a/sys/net80211/ieee80211_ioctl.h b/sys/net80211/ieee80211_ioctl.h
index 94931282fe5..98c08a621b1 100644
--- a/sys/net80211/ieee80211_ioctl.h
+++ b/sys/net80211/ieee80211_ioctl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_ioctl.h,v 1.39 2019/09/02 12:54:21 stsp Exp $	*/
+/*	$OpenBSD: ieee80211_ioctl.h,v 1.40 2020/04/29 13:13:30 stsp Exp $	*/
 /*	$NetBSD: ieee80211_ioctl.h,v 1.7 2004/04/30 22:51:04 dyoung Exp $	*/
 
 /*-
@@ -412,7 +412,8 @@ struct ieee80211_nodereq_all {
 #define IEEE80211_F_NOBRIDGE	0x00000002	/* CONF: no internal bridging */
 #define IEEE80211_F_HOSTAPMASK	0x00000003
 #define IEEE80211_F_STAYAUTH	0x00000004	/* CONF: ignore deauth */
-#define IEEE80211_F_USERBITS	"\20\01HIDENWID\02NOBRIDGE\03STAYAUTH"
+#define IEEE80211_F_NOMIMO	0x00000008	/* CONF: disable MIMO */
+#define IEEE80211_F_USERBITS	"\20\01HIDENWID\02NOBRIDGE\03STAYAUTH\04NOMIMO"
 
 struct ieee80211_flags {
 	const char		*f_name;
@@ -422,7 +423,8 @@ struct ieee80211_flags {
 #define IEEE80211_FLAGS	{			\
 	{ "hidenwid", IEEE80211_F_HIDENWID },	\
 	{ "nobridge", IEEE80211_F_NOBRIDGE },	\
-	{ "stayauth", IEEE80211_F_STAYAUTH }	\
+	{ "stayauth", IEEE80211_F_STAYAUTH },	\
+	{ "nomimo", IEEE80211_F_NOMIMO }	\
 }
 
 #define SIOCG80211FLAGS		_IOWR('i', 216, struct ifreq)