qcacld-3.0: Handle ACS freq list zero

When all chan in ACS freq list is filtered out
by wlan_hdd_trim_acs_channel_list, the hostapd start will
fail. This happens when PCL is PM_24G_SCC_CH_SBS_CH,
and SAP acs range includes 5G channel list.
One example is STA active on 6Ghz chan. Hostapd start
SAP on 5G ACS range. The intersection of PCL and ACS range
is zero.
Instead of ACS failure, add API wlan_hdd_handel_zero_acs_list
to select one channel from ACS range and report to Hostapd.
When hostapd "start_ap", the driver will force SCC to 6G
or move SAP to 2G based on SAP's configuration.

Change-Id: Ice8bef2a82f43940c570c74c0af8b05d18159f52
CRs-Fixed: 2603699

core/hdd/src/wlan_hdd_cfg80211.c

@@ -2770,6 +2770,64 @@ static void wlan_hdd_trim_acs_channel_list(uint32_t *pcl, uint8_t pcl_count,
 	*org_ch_list_count = ch_list_count;
 }
 
+/**
+ * wlan_hdd_handle_zero_acs_list() - Handle worst case of acs channel
+ * trimmed to zero
+ * @hdd_ctx: struct hdd_context
+ * @org_ch_list: ACS channel list from user space
+ * @org_ch_list_count: ACS channel count from user space
+ *
+ * When all chan in ACS freq list is filtered out
+ * by wlan_hdd_trim_acs_channel_list, the hostapd start will fail.
+ * This happens when PCL is PM_24G_SCC_CH_SBS_CH, and SAP acs range includes
+ * 5G channel list. One example is STA active on 6Ghz chan. Hostapd
+ * start SAP on 5G ACS range. The intersection of PCL and ACS range is zero.
+ * Instead of ACS failure, this API selects one channel from ACS range
+ * and report to Hostapd. When hostapd do start_ap, the driver will
+ * force SCC to 6G or move SAP to 2G based on SAP's configuration.
+ *
+ * Return: None
+ */
+static void wlan_hdd_handle_zero_acs_list(struct hdd_context *hdd_ctx,
+					  uint32_t *acs_freq_list,
+					  uint8_t *acs_ch_list_count,
+					  uint32_t *org_freq_list,
+					  uint8_t org_ch_list_count)
+{
+	uint16_t i, sta_count;
+	uint32_t acs_chan_default = 0;
+
+	if (!acs_ch_list_count || *acs_ch_list_count > 0 ||
+	    !acs_freq_list) {
+		return;
+	}
+	if (!org_ch_list_count || !org_freq_list)
+		return;
+
+	if (!policy_mgr_is_force_scc(hdd_ctx->psoc))
+		return;
+	sta_count = policy_mgr_mode_specific_connection_count
+			(hdd_ctx->psoc, PM_STA_MODE, NULL);
+	sta_count += policy_mgr_mode_specific_connection_count
+			(hdd_ctx->psoc, PM_P2P_CLIENT_MODE, NULL);
+	if (!sta_count)
+		return;
+
+	for (i = 0; i < org_ch_list_count; i++) {
+		if (!wlan_reg_is_dfs_for_freq(hdd_ctx->pdev,
+					      org_freq_list[i])) {
+			acs_chan_default = org_freq_list[i];
+			break;
+		}
+	}
+	if (!acs_chan_default)
+		acs_chan_default = org_freq_list[0];
+
+	acs_freq_list[0] = acs_chan_default;
+	*acs_ch_list_count = 1;
+	hdd_debug("retore acs chan list to single freq %d", acs_chan_default);
+}
+
 /**
  * __wlan_hdd_cfg80211_do_acs(): CFG80211 handler function for DO_ACS Vendor CMD
  * @wiphy:  Linux wiphy struct pointer
@@ -2918,7 +2976,7 @@ static int __wlan_hdd_cfg80211_do_acs(struct wiphy *wiphy,
 
 	qdf_mem_zero(&sap_config->acs_cfg, sizeof(struct sap_acs_cfg));
 
-	hdd_debug("channel width =%d", ch_width);
+	hdd_debug("channel width =%d hw_mode %d", ch_width, hw_mode);
 	if (ch_width == 160)
 		sap_config->acs_cfg.ch_width = CH_WIDTH_160MHZ;
 	else if (ch_width == 80)
@@ -3036,7 +3094,14 @@ static int __wlan_hdd_cfg80211_do_acs(struct wiphy *wiphy,
 					sap_config->acs_cfg.pcl_ch_count,
 					sap_config->acs_cfg.freq_list,
 					&sap_config->acs_cfg.ch_list_count);
-
+		if (!sap_config->acs_cfg.ch_list_count &&
+		    sap_config->acs_cfg.master_ch_list_count)
+			wlan_hdd_handle_zero_acs_list(
+				hdd_ctx,
+				sap_config->acs_cfg.freq_list,
+				&sap_config->acs_cfg.ch_list_count,
+				sap_config->acs_cfg.master_freq_list,
+				sap_config->acs_cfg.master_ch_list_count);
 		/* if it is only one channel, send ACS event to upper layer */
 		if (sap_config->acs_cfg.ch_list_count == 1) {
 			sap_config->acs_cfg.pri_ch_freq =