iwlwifi: mvm: update the rssi calculation

Make the rssi more accurate by taking in count per-chain AGC
values. Without this, the RSSI reports inaccurate values.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 23 insertions, 14 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/rx.c b/drivers/net/wireless/iwlwifi/mvm/rx.c
index 3f40ab05bbd8..b0b190d0ec23 100644
--- a/drivers/net/wireless/iwlwifi/mvm/rx.c
+++ b/drivers/net/wireless/iwlwifi/mvm/rx.c
@@ -131,33 +131,42 @@ static void iwl_mvm_pass_packet_to_mac80211(struct iwl_mvm *mvm,
 static int iwl_mvm_calc_rssi(struct iwl_mvm *mvm,
                              struct iwl_rx_phy_info *phy_info)
 {
-        u32 rssi_a, rssi_b, rssi_c, max_rssi, agc_db;
+        int rssi_a, rssi_b, rssi_a_dbm, rssi_b_dbm, max_rssi_dbm;
+        int rssi_all_band_a, rssi_all_band_b;
+        u32 agc_a, agc_b, max_agc;
         u32 val;
 
-        /* Find max rssi among 3 possible receivers.
+        /* Find max rssi among 2 possible receivers.
          * These values are measured by the Digital Signal Processor (DSP).
          * They should stay fairly constant even as the signal strength varies,
          * if the radio's Automatic Gain Control (AGC) is working right.
          * AGC value (see below) will provide the "interesting" info.
          */
+        val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_AGC_IDX]);
+        agc_a = (val & IWL_OFDM_AGC_A_MSK) >> IWL_OFDM_AGC_A_POS;
+        agc_b = (val & IWL_OFDM_AGC_B_MSK) >> IWL_OFDM_AGC_B_POS;
+        max_agc = max_t(u32, agc_a, agc_b);
+
         val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_RSSI_AB_IDX]);
         rssi_a = (val & IWL_OFDM_RSSI_INBAND_A_MSK) >> IWL_OFDM_RSSI_A_POS;
         rssi_b = (val & IWL_OFDM_RSSI_INBAND_B_MSK) >> IWL_OFDM_RSSI_B_POS;
-        val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_RSSI_C_IDX]);
-        rssi_c = (val & IWL_OFDM_RSSI_INBAND_C_MSK) >> IWL_OFDM_RSSI_C_POS;
-
-        val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_AGC_IDX]);
-        agc_db = (val & IWL_OFDM_AGC_DB_MSK) >> IWL_OFDM_AGC_DB_POS;
+        rssi_all_band_a = (val & IWL_OFDM_RSSI_ALLBAND_A_MSK) >>
+                                IWL_OFDM_RSSI_ALLBAND_A_POS;
+        rssi_all_band_b = (val & IWL_OFDM_RSSI_ALLBAND_B_MSK) >>
+                                IWL_OFDM_RSSI_ALLBAND_B_POS;
 
-        max_rssi = max_t(u32, rssi_a, rssi_b);
-        max_rssi = max_t(u32, max_rssi, rssi_c);
+        /*
+         * dBm = rssi dB - agc dB - constant.
+         * Higher AGC (higher radio gain) means lower signal.
+         */
+        rssi_a_dbm = rssi_a - IWL_RSSI_OFFSET - agc_a;
+        rssi_b_dbm = rssi_b - IWL_RSSI_OFFSET - agc_b;
+        max_rssi_dbm = max_t(int, rssi_a_dbm, rssi_b_dbm);
 
-        IWL_DEBUG_STATS(mvm, "Rssi In A %d B %d C %d Max %d AGC dB %d\n",
-                        rssi_a, rssi_b, rssi_c, max_rssi, agc_db);
+        IWL_DEBUG_STATS(mvm, "Rssi In A %d B %d Max %d AGCA %d AGCB %d\n",
+                        rssi_a_dbm, rssi_b_dbm, max_rssi_dbm, agc_a, agc_b);
 
-        /* dBm = max_rssi dB - agc dB - constant.
-         * Higher AGC (higher radio gain) means lower signal. */
-        return max_rssi - agc_db - IWL_RSSI_OFFSET;
+        return max_rssi_dbm;
 }
 
 /*