qcacld-3.0: Allow channel 12, 13 in 2.4ghz for ACS

Currently the driver does not allow the channels
12 and 13 for SAP ACS because most of the legacy
stations don't scan them and they can cause many
IOT issues. But if they are the only channels left
in the spectrum (for eg. all other channels became
unsafe), then the SAP would fail as the driver did
not consider channel 12-14 for ACS.

Fix is to consider 12-14 for ACS, remove them if
other channels are available and if they are the
only channels available in the spectrum, then start
the SAP on any one of these channels.

Change-Id: I599d0e95e9bdc3aed70d6a515d7a52c39846b6f2
CRs-Fixed: 2576635

core/sap/src/sap_api_link_cntl.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2019 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2020 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -275,6 +275,36 @@ wlansap_filter_unsafe_ch(struct wlan_objmgr_psoc *psoc,
 		sap_debug("Safe freq %d", sap_ctx->acs_cfg->freq_list[i]);
 }
 
+static void
+wlan_sap_filter_non_preferred_channels(struct wlan_objmgr_pdev *pdev,
+				       struct sap_context *sap_ctx)
+{
+	uint16_t i;
+	uint16_t num_ch = 0;
+	bool preferred_freq_found = false;
+
+	for (i = 0; i < sap_ctx->acs_cfg->ch_list_count; i++) {
+		if (sap_ctx->acs_cfg->freq_list[i] == 2467 ||
+		    sap_ctx->acs_cfg->freq_list[i] == 2472 ||
+		    sap_ctx->acs_cfg->freq_list[i] == 2477) {
+			sap_debug("Skip freq %d if preferred freq present",
+				  sap_ctx->acs_cfg->freq_list[i]);
+			continue;
+		}
+		sap_ctx->acs_cfg->freq_list[num_ch++] =
+						sap_ctx->acs_cfg->freq_list[i];
+		preferred_freq_found = true;
+	}
+
+	if (!preferred_freq_found) {
+		sap_debug("No preferred freq, list unchanged");
+		return;
+	}
+	sap_debug("preferred frequencies found updated ACS ch list len %d",
+		  num_ch);
+	sap_ctx->acs_cfg->ch_list_count = num_ch;
+}
+
 QDF_STATUS wlansap_pre_start_bss_acs_scan_callback(mac_handle_t mac_handle,
 						   struct sap_context *sap_ctx,
 						   uint8_t sessionid,
@@ -290,6 +320,7 @@ QDF_STATUS wlansap_pre_start_bss_acs_scan_callback(mac_handle_t mac_handle,
 	/* This has to be done before the ACS selects default channel */
 	wlansap_filter_unsafe_ch(mac_ctx->psoc, sap_ctx);
 
+	wlan_sap_filter_non_preferred_channels(mac_ctx->pdev, sap_ctx);
 	if (!sap_ctx->acs_cfg->ch_list_count) {
 		sap_err("No channel left for SAP operation, hotspot fail");
 		sap_ctx->chan_freq = SAP_CHANNEL_NOT_SELECTED;

core/sap/src/sap_fsm.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2019 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2020 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -3330,10 +3330,6 @@ static QDF_STATUS sap_get_freq_list(struct sap_context *sap_ctx,
 		if (start_ch_freq > WLAN_REG_CH_TO_FREQ(loop_count) ||
 		    end_ch_freq < WLAN_REG_CH_TO_FREQ(loop_count))
 			continue;
-		/* Skip channel 12, and 13 for IOT issues for now */
-		if (loop_count == CHAN_ENUM_2467 ||
-		    loop_count == CHAN_ENUM_2472)
-			continue;
 		/*
 		 * go to next channel if none of these condition pass
 		 * - DFS scan enabled and chan not in CHANNEL_STATE_DISABLE