iwlwifi: add support for 12K Receive Buffers

802.11ac allows A-MSDU that can be up to 12KB long. Since
an entire A-MSDU needs to fit into one single Receive
Buffer (RB), add support for big RBs.
Since this adds lots of pressure to the memory manager and
significantly increase the true_size of the RX buffers,
don't enable this by default.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-modparams.h b/drivers/net/wireless/intel/iwlwifi/iwl-modparams.h
index ac2b90d..3436c00 100644
--- a/drivers/net/wireless/intel/iwlwifi/iwl-modparams.h
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-modparams.h
@@ -86,6 +86,12 @@
 	IWL_ENABLE_HT_TXAGG	 = BIT(3),
 };
 
+enum iwl_amsdu_size {
+	IWL_AMSDU_4K = 0,
+	IWL_AMSDU_8K = 1,
+	IWL_AMSDU_12K = 2,
+};
+
 /**
  * struct iwl_mod_params
  *
@@ -94,7 +100,7 @@
  * @sw_crypto: using hardware encryption, default = 0
  * @disable_11n: disable 11n capabilities, default = 0,
  *	use IWL_[DIS,EN]ABLE_HT_* constants
- * @amsdu_size_8K: enable 8K amsdu size, default = 0
+ * @amsdu_size: enable 8K amsdu size, default = 4K. enum iwl_amsdu_size.
  * @restart_fw: restart firmware, default = 1
  * @bt_coex_active: enable bt coex, default = true
  * @led_mode: system default, default = 0
@@ -109,7 +115,7 @@
 struct iwl_mod_params {
 	int sw_crypto;
 	unsigned int disable_11n;
-	int amsdu_size_8K;
+	int amsdu_size;
 	bool restart_fw;
 	bool bt_coex_active;
 	int led_mode;