iwlwifi: use only one chain for scan in PS

When doing scan in power saving mode, choose only 1 valid RX chain instead of
turning all chains on.

Signed-off-by: Shanyu Zhao <shanyu.zhao@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-scan.c b/drivers/net/wireless/iwlwifi/iwl-scan.c
index 1eb0d0bf1fe4..48bc2636a8ef 100644
--- a/drivers/net/wireless/iwlwifi/iwl-scan.c
+++ b/drivers/net/wireless/iwlwifi/iwl-scan.c
@@ -581,6 +581,7 @@ static void iwl_bg_request_scan(struct work_struct *data)
         u8 rate;
         bool is_active = false;
         int  chan_mod;
+        u8 active_chains;
 
         conf = ieee80211_get_hw_conf(priv->hw);
 
@@ -734,9 +735,22 @@ static void iwl_bg_request_scan(struct work_struct *data)
         rate_flags |= iwl_ant_idx_to_flags(priv->scan_tx_ant[band]);
         scan->tx_cmd.rate_n_flags = iwl_hw_set_rate_n_flags(rate, rate_flags);
 
+        /* In power save mode use one chain, otherwise use all chains */
+        if (test_bit(STATUS_POWER_PMI, &priv->status)) {
+                /* rx_ant has been set to all valid chains previously */
+                active_chains = rx_ant &
+                                ((u8)(priv->chain_noise_data.active_chains));
+                if (!active_chains)
+                        active_chains = rx_ant;
+
+                IWL_DEBUG_SCAN(priv, "chain_noise_data.active_chains: %u\n",
+                                priv->chain_noise_data.active_chains);
+
+                rx_ant = first_antenna(active_chains);
+        }
         /* MIMO is not used here, but value is required */
         rx_chain |= ANT_ABC << RXON_RX_CHAIN_VALID_POS;
-        rx_chain |= ANT_ABC << RXON_RX_CHAIN_FORCE_MIMO_SEL_POS;
+        rx_chain |= rx_ant << RXON_RX_CHAIN_FORCE_MIMO_SEL_POS;
         rx_chain |= rx_ant << RXON_RX_CHAIN_FORCE_SEL_POS;
         rx_chain |= 0x1 << RXON_RX_CHAIN_DRIVER_FORCE_POS;
         scan->rx_chain = cpu_to_le16(rx_chain);