iwlwifi: add documentation for bt reduced tx power

Change-Id: Ia6294d651dcffdcaf8b62e67bcef52bd8c158dea
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Reviewed-on: http://git-mwg.jer.intel.com/gerrit/1947
Tested-by: Jenkins
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
index 9d88565..cb4b31f 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
@@ -274,9 +274,20 @@ void iwlagn_send_advance_bt_config(struct iwl_priv *priv)
                return;
        }
 
+       /*
+        * Possible situations when BT needs to take over for receive,
+        * at the same time where STA needs to response to AP's frame(s),
+        * reduce the tx power of the required response frames, by that,
+        * allow the concurrent BT receive & WiFi transmit
+        * (BT - ANT A, WiFi -ANT B), without interference to one another
+        *
+        * Reduced tx power apply to control frames only (ACK/Back/CTS)
+        * when indicated by the BT config command
+        */
        basic.kill_ack_mask = priv->kill_ack_mask;
        basic.kill_cts_mask = priv->kill_cts_mask;
-       basic.reduce_txpower = priv->reduced_txpower;
+       if (priv->reduced_txpower)
+               basic.reduce_txpower = IWLAGN_BT_REDUCED_TX_PWR;
        basic.valid = priv->bt_valid;
 
        /*
@@ -590,6 +601,15 @@ static bool iwlagn_set_kill_msk(struct iwl_priv *priv,
        return need_update;
 }
 
+/*
+ * Upon RSSI changes, sends a bt config command with following changes
+ *  1. enable/disable "reduced control frames tx power
+ *  2. update the "kill)ack_mask" and "kill_cts_mask"
+ *
+ * If "reduced tx power" is enabled, uCode shall
+ *  1. ACK/Back/CTS rate shall reduced to 6Mbps
+ *  2. not use duplciate 20/40MHz mode
+ */
 static bool iwlagn_fill_txpower_mode(struct iwl_priv *priv,
                                struct iwl_bt_uart_msg *uart_msg)
 {

diff --git a/drivers/net/wireless/iwlwifi/iwl-commands.h b/drivers/net/wireless/iwlwifi/iwl-commands.h
index 83a6930..2813a0a 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-commands.h
@@ -1910,6 +1910,8 @@ enum iwl_bt_kill_idx {
                                        IWLAGN_BT_VALID_REDUCED_TX_PWR | \
                                        IWLAGN_BT_VALID_3W_LUT)
 
+#define IWLAGN_BT_REDUCED_TX_PWR       BIT(0)
+
 #define IWLAGN_BT_DECISION_LUT_SIZE    12
 
 struct iwl_basic_bt_cmd {
@@ -1923,6 +1925,10 @@ struct iwl_basic_bt_cmd {
        u8 bt3_timer_t2_value;
        __le16 bt4_reaction_time; /* unused */
        __le32 bt3_lookup_table[IWLAGN_BT_DECISION_LUT_SIZE];
+       /*
+        * bit 0: use reduced tx power for control frame
+        * bit 1 - 7: reserved
+        */
        u8 reduce_txpower;
        u8 reserved;
        __le16 valid;