ath10k: AP: handle HT station which does not have HT RX MCS

This is a workaround for HT-enabled STAs which break the spec
and have no HT capabilities RX mask (no HT RX MCS map).

As per spec, in section 20.3.5 Modulation and coding scheme (MCS),
MCS 0 through 7 are mandatory in 20MHz with 800 ns GI at all STAs.

Firmware asserts if such situation occurs.
Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/mac.c

@@ -1148,8 +1148,23 @@ static void ath10k_peer_assoc_h_ht(struct ath10k *ar,
 		if (ht_cap->mcs.rx_mask[i/8] & (1 << i%8))
 			arg->peer_ht_rates.rates[n++] = i;
 
+	/*
+	 * This is a workaround for HT-enabled STAs which break the spec
+	 * and have no HT capabilities RX mask (no HT RX MCS map).
+	 *
+	 * As per spec, in section 20.3.5 Modulation and coding scheme (MCS),
+	 * MCS 0 through 7 are mandatory in 20MHz with 800 ns GI at all STAs.
+	 *
+	 * Firmware asserts if such situation occurs.
+	 */
+	if (n == 0) {
+		arg->peer_ht_rates.num_rates = 8;
+		for (i = 0; i < arg->peer_ht_rates.num_rates; i++)
+			arg->peer_ht_rates.rates[i] = i;
+	} else {
 		arg->peer_ht_rates.num_rates = n;
 		arg->peer_num_spatial_streams = sta->rx_nss;
+	}
 
 	ath10k_dbg(ATH10K_DBG_MAC, "mac ht peer %pM mcs cnt %d nss %d\n",
 		   arg->addr,