wifi: iwlwifi: mei: make mei filtered scan more aggressive

When mei filtered scan is performed, it must find the AP on the first
scan, otherwise CSME will take the ownership of the NIC.
Make this scan more aggressive by scanning the channel the AP is
supposed to be on (as reported by CSME) several times.
Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230418122405.47e383b10b18.I14340a118acdb19ecb7214e7ff413054c77bd99c@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/scan.c

@@ -45,6 +45,9 @@
 /* minimal number of 2GHz and 5GHz channels in the regular scan request */
 #define IWL_MVM_6GHZ_PASSIVE_SCAN_MIN_CHANS 4
 
+/* Number of iterations on the channel for mei filtered scan */
+#define IWL_MEI_SCAN_NUM_ITER	5U
+
 struct iwl_mvm_scan_timing_params {
 	u32 suspend_time;
 	u32 max_out_time;
@@ -2665,6 +2668,7 @@ static void iwl_mvm_mei_limited_scan(struct iwl_mvm *mvm,
 	struct iwl_mvm_csme_conn_info *info = iwl_mvm_get_csme_conn_info(mvm);
 	struct iwl_mei_conn_info *conn_info;
 	struct ieee80211_channel *chan;
+	int scan_iters, i;
 
 	if (!info) {
 		IWL_DEBUG_SCAN(mvm, "mei_limited_scan: no connection info\n");
@@ -2690,8 +2694,16 @@ static void iwl_mvm_mei_limited_scan(struct iwl_mvm *mvm,
 		return;
 	}
 
-	params->n_channels = 1;
-	params->channels[0] = chan;
+	/* The mei filtered scan must find the AP, otherwise CSME will
+	 * take the NIC ownership. Add several iterations on the channel to
+	 * make the scan more robust.
+	 */
+	scan_iters = min(IWL_MEI_SCAN_NUM_ITER, params->n_channels);
+	params->n_channels = scan_iters;
+	for (i = 0; i < scan_iters; i++)
+		params->channels[i] = chan;
+
+	IWL_DEBUG_SCAN(mvm, "Mei scan: num iterations=%u\n", scan_iters);
 
 	params->n_ssids = 1;
 	params->ssids[0].ssid_len = conn_info->ssid_len;