On Thu, 02 Apr 2026 09:14:46 +0200,
Stefan Sperling <stsp@stsp.name> wrote:
> 
> On Thu, Apr 02, 2026 at 12:39:32AM +0200, Kirill A. Korinsky wrote:
> > tech@,
> > 
> > Here the next small bit of my iwx rework.
> > 
> > I follow iwlwifi and advertise RX antenna pattern only when RX is
> > effectively 1x1: there is one usable RX antenna, or MIMO is disabled.
> > 
> > OK?
> 
> By itself, I believe this change won't have any effect. As far as
> I understand the antenna pattern is related to beamforming.
> 
> Is this change prepraring us for beamforming support on the Rx side,
> i.e. the AP will be able to use beamforming when sending us data?
> 
> What else will be needed for this?
>

I think the right path is:

1. TX antenna
2. + RX antenna and STBC
3. + beamformee
4. + LDPC

(1) is harmless and trivial, but since (2) some firmware commands are here.

So, here 1 + 2 steps in one diff where I follow iwlwifi for antenna pattern
and STBC advertisement. Advertise RX antenna pattern only when RX is
effectively 1x1; advertise HT and VHT STBC unconditionally, and VHT TX
antenna pattern only when TX is effectively 1x1, and program the firmware
TLC STBC flag when the peer advertises RX STBC and the device has more than
one valid TX antenna.

Index: sys/dev/pci/if_iwx.c
===================================================================
RCS file: /home/cvs/src/sys/dev/pci/if_iwx.c,v
diff -u -p -r1.227 if_iwx.c
--- sys/dev/pci/if_iwx.c	1 Apr 2026 02:29:37 -0000	1.227
+++ sys/dev/pci/if_iwx.c	2 Apr 2026 09:40:03 -0000
@@ -3149,6 +3149,13 @@ iwx_fw_valid_rx_ant(struct iwx_softc *sc
 	return rx_ant;
 }
 
+int
+iwx_fw_num_ant(uint8_t ant)
+{
+	return !!(ant & IWX_ANT_A) + !!(ant & IWX_ANT_B) +
+	    !!(ant & IWX_ANT_C);
+}
+
 void
 iwx_init_channel_map(struct iwx_softc *sc, uint16_t *channel_profile_v3,
     uint32_t *channel_profile_v4, int nchan_profile)
@@ -3250,6 +3257,13 @@ iwx_setup_ht_rates(struct iwx_softc *sc)
 	memset(ic->ic_sup_mcs, 0, sizeof(ic->ic_sup_mcs));
 	ic->ic_sup_mcs[0] = 0xff;		/* MCS 0-7 */
 
+	ic->ic_htcaps &= ~(IEEE80211_HTCAP_TXSTBC |
+	    IEEE80211_HTCAP_RXSTBC_MASK);
+	ic->ic_htcaps |= (1 << IEEE80211_HTCAP_RXSTBC_SHIFT);
+
+	if (iwx_fw_num_ant(iwx_fw_valid_tx_ant(sc)) > 1)
+		ic->ic_htcaps |= IEEE80211_HTCAP_TXSTBC;
+
 	if (!iwx_mimo_enabled(sc))
 		return;
 
@@ -3264,8 +3278,30 @@ iwx_setup_vht_rates(struct iwx_softc *sc
 {
 	struct ieee80211com *ic = &sc->sc_ic;
 	uint8_t rx_ant = iwx_fw_valid_rx_ant(sc);
+	uint8_t tx_ant = iwx_fw_valid_tx_ant(sc);
+	int num_rx_ant = iwx_fw_num_ant(rx_ant);
+	int num_tx_ant = iwx_fw_num_ant(tx_ant);
 	int n;
 
+	if (sc->sc_nvm.sku_cap_mimo_disable) {
+		num_rx_ant = 1;
+		num_tx_ant = 1;
+	}
+
+	ic->ic_vhtcaps &= ~(IEEE80211_VHTCAP_RX_ANT_PATTERN |
+	    IEEE80211_VHTCAP_TX_ANT_PATTERN |
+	    IEEE80211_VHTCAP_TX_STBC |
+	    IEEE80211_VHTCAP_RX_STBC_SS_MASK);
+	ic->ic_vhtcaps |= (1 << IEEE80211_VHTCAP_RX_STBC_SS_SHIFT);
+
+	if (num_rx_ant == 1)
+		ic->ic_vhtcaps |= IEEE80211_VHTCAP_RX_ANT_PATTERN;
+	if (num_tx_ant > 1)
+		ic->ic_vhtcaps |= IEEE80211_VHTCAP_TX_STBC;
+	else
+		ic->ic_vhtcaps |= IEEE80211_VHTCAP_TX_ANT_PATTERN;
+
 	ic->ic_vht_rxmcs = (IEEE80211_VHT_MCS_0_9 <<
 	    IEEE80211_VHT_MCS_FOR_SS_SHIFT(1));
 
@@ -8511,6 +8547,14 @@ iwx_rs_init_v3(struct iwx_softc *sc, str
 		cfg_cmd.max_mpdu_len = htole16(3839);
 	else
 		cfg_cmd.max_mpdu_len = IEEE80211_MAX_LEN;
+	if (iwx_fw_num_ant(iwx_fw_valid_tx_ant(sc)) > 1) {
+		if ((ni->ni_flags & IEEE80211_NODE_VHT) &&
+		    (ni->ni_vhtcaps & IEEE80211_VHTCAP_RX_STBC_SS_MASK))
+			cfg_cmd.flags |= htole16(IWX_TLC_MNG_CFG_FLAGS_STBC_MSK);
+		else if ((ni->ni_flags & IEEE80211_NODE_HT) &&
+		    (ni->ni_htcaps & IEEE80211_HTCAP_RXSTBC_MASK))
+			cfg_cmd.flags |= htole16(IWX_TLC_MNG_CFG_FLAGS_STBC_MSK);
+	}
 	if (ni->ni_flags & IEEE80211_NODE_HT) {
 		if (ieee80211_node_supports_ht_sgi20(ni)) {
 			cfg_cmd.sgi_ch_width_supp |= (1 <<
@@ -8607,6 +8651,14 @@ iwx_rs_init_v4(struct iwx_softc *sc, str
 		cfg_cmd.max_mpdu_len = htole16(3839);
 	else
 		cfg_cmd.max_mpdu_len = IEEE80211_MAX_LEN;
+	if (iwx_fw_num_ant(iwx_fw_valid_tx_ant(sc)) > 1) {
+		if ((ni->ni_flags & IEEE80211_NODE_VHT) &&
+		    (ni->ni_vhtcaps & IEEE80211_VHTCAP_RX_STBC_SS_MASK))
+			cfg_cmd.flags |= htole16(IWX_TLC_MNG_CFG_FLAGS_STBC_MSK);
+		else if ((ni->ni_flags & IEEE80211_NODE_HT) &&
+		    (ni->ni_htcaps & IEEE80211_HTCAP_RXSTBC_MASK))
+			cfg_cmd.flags |= htole16(IWX_TLC_MNG_CFG_FLAGS_STBC_MSK);
+	}
 	if (ni->ni_flags & IEEE80211_NODE_HT) {
 		if (ieee80211_node_supports_ht_sgi20(ni)) {
 			cfg_cmd.sgi_ch_width_supp |= (1 <<
@@ -12474,8 +12526,7 @@ iwx_attach(struct device *parent, struct
 	    IEEE80211_VHTCAP_MAX_AMPDU_LEN_SHIFT) |
 	    (IEEE80211_VHTCAP_CHAN_WIDTH_160 <<
 		IEEE80211_VHTCAP_CHAN_WIDTH_SHIFT) |
-	    IEEE80211_VHTCAP_SGI80 | IEEE80211_VHTCAP_SGI160 |
-	    IEEE80211_VHTCAP_RX_ANT_PATTERN | IEEE80211_VHTCAP_TX_ANT_PATTERN;
+	    IEEE80211_VHTCAP_SGI80 | IEEE80211_VHTCAP_SGI160;
 
 	ic->ic_sup_rates[IEEE80211_MODE_11A] = ieee80211_std_rateset_11a;
 	ic->ic_sup_rates[IEEE80211_MODE_11B] = ieee80211_std_rateset_11b;


-- 
wbr, Kirill