iwlagn: Enable/disable PS poll based on RSSI and BT coex traffic state

WiFi throughput drops drastically when BT is turned on, BT and WiFi
are simultaneously transmitting/receiving traffic. This is particularly true
when BT has higher priority over WiFi, and hence the device defers TX frames.
The AP assumes that the channel is bad and reduces the data rate, implying
longer airtime, which exacerbates the problem further, resulting ultimately
in what is popularly called the "death-spiral" phenomenon. The use of PS-poll
in such scenarios guarantees a low but consistent throughput.

Since the death-spiral phenomenon is observed only when the RSSI is low, use
PS-poll only when RSSI is low and disable when high, with a known hysterisis.

This feature specifies the high and low thresholds and implements the
callbacks registered with mac80211, which will be called when threshold events
occur.

iwlwifi: dynamic pspoll: optimize rssi monitor code

Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.h b/drivers/net/wireless/iwlwifi/iwl-agn.h
index bde03b4..81a009b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.h
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.h
@@ -261,6 +261,8 @@ void iwlagn_bt_coex_profile_notif(struct iwl_priv *priv,
 void iwlagn_bt_rx_handler_setup(struct iwl_priv *priv);
 void iwlagn_bt_setup_deferred_work(struct iwl_priv *priv);
 void iwlagn_bt_cancel_deferred_work(struct iwl_priv *priv);
+void iwlagn_bt_coex_rssi_monitor(struct iwl_priv *priv);
+void iwlagn_bt_adjust_rssi_monitor(struct iwl_priv *priv, bool rssi_ena);
 
 #ifdef CONFIG_IWLWIFI_DEBUG
 const char *iwl_get_tx_fail_reason(u32 status);