Changes between Version 8 and Version 9 of 802.11/wlan_exp/Extending

Timestamp:

Dec 14, 2015, 9:55:26 PM (8 years ago)

Author:

murphpo

Comment:

--

802.11/wlan_exp/Extending

@@ -62 +62 @@
 The {{{process_user_cmd()}}} and {{{wlan_exp_process_user_cmd()}}} functions executed outside the context of an interrupt service routine. As a result these functions may be interrupted at any time. Almost all processing in CPU High occurs in ISR contexts, including all processing of wireless and Ethernet Tx/Rx. If your command handler accesses or modifies data structures that might be modified in one of the upper-level MAC's interrupt service routines, you must take precautions to avoid bad states.
 
-The easiest way to protect a command handler from bad states due to unexpected interrupts is to disable interrupts during execution of the handler. 
+The easiest way to protect a command handler from bad states due to unexpected interrupts is to disable interrupts during execution of the handler. However disabling interrupts will have performance implications. When interrupts are disabled all packet processing is disabled in CPU High. This means no new Ethernet receptions can be processed, no new MPDUs can be submitted to CPU Low for transmission, and no wireless receptions will be processed. It also means all scheduled events will be postponed, including all LTG callbacks and beacon transmissions. You should always minimize the length of time interrupts are disabled.
+
+The MAC High Framework provides helper functions for disabling and restoring the interrupt controller state:
 
 {{{#!c
@@ -80 +82 @@
 
 
+
 '''TODO:'''
  * Endianness
- * Interrupt safety
 
 === Example Command: Reading Tx Queue Status ===
@@ -126 +128 @@
 In this example the custom command will query the lengths of Tx queues. 
 Modify the {{{wlan_exp_user_ap_process_cmd()}}} function in {{{wlan_mac_ap.c}}}.
-{{{#!C
-    #define USER_CMDID_TX_QUEUE_STATUS 100
-    int i;
-    u32 req_queue_id;
-    u32 q_id, q_occ;
-        dl_entry* curr_station_info_entry;
-        station_info* curr_station_info;
+{{{#!c
+
+#define USER_CMDID_TX_QUEUE_STATUS 100
+int i;
+u32 req_queue_id;
+u32 q_id, q_occ;
+dl_entry* curr_station_info_entry;
+station_info* curr_station_info;
 }}}