From: Pradeep kumar Chitrapu <pradeepc@codeaurora.org>
Date: Mon, 10 Dec 2018 20:56:11 -0800
Subject: ath10k: fix incorrect multicast/broadcast rate setting

Invalid rate code is sent to firmware when multicast rate value of 0 is
sent to driver indicating disabled case, causing broken mesh path.
so fix that.

Tested on QCA9984 with firmware 10.4-3.6.1-00827

Fixes: cd93b83ad92 ("ath10k: support for multicast rate control")
Co-developed-by: Zhi Chen <zhichen@codeaurora.org>
Signed-off-by: Zhi Chen <zhichen@codeaurora.org>
Signed-off-by: Pradeep Kumar Chitrapu <pradeepc@codeaurora.org>

Origin: other, https://patchwork.kernel.org/patch/10723033/

--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -5494,8 +5494,8 @@ static void ath10k_bss_info_changed(stru
 	struct cfg80211_chan_def def;
 	u32 vdev_param, pdev_param, slottime, preamble;
 	u16 bitrate, hw_value;
-	u8 rate, basic_rate_idx;
-	int rateidx, ret = 0, hw_rate_code;
+	u8 rate, basic_rate_idx, rateidx;
+	int ret = 0, hw_rate_code, mcast_rate;
 	enum nl80211_band band;
 	const struct ieee80211_supported_band *sband;
 
@@ -5668,7 +5668,11 @@ static void ath10k_bss_info_changed(stru
 	if (changed & BSS_CHANGED_MCAST_RATE &&
 	    !ath10k_mac_vif_chan(arvif->vif, &def)) {
 		band = def.chan->band;
-		rateidx = vif->bss_conf.mcast_rate[band] - 1;
+		mcast_rate = vif->bss_conf.mcast_rate[band];
+		if (mcast_rate > 0)
+			rateidx = mcast_rate - 1;
+		else
+			rateidx = ffs(vif->bss_conf.basic_rates) - 1;
 
 		if (ar->phy_capability & WHAL_WLAN_11A_CAPABILITY)
 			rateidx += ATH10K_MAC_FIRST_OFDM_RATE_IDX;