iwlwifi: change byte count table for a000 devices

Since TFD was enlarged to 256 bytes, the fetch of the TFD
itself is very expensive.
To make DRAM to SRAM more efficient, bits 12-13 will indicate
the number of 64 byte chunks that should be transferred to
SRAM.
Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/iwl-fh.h

@@ -734,8 +734,13 @@ struct iwl_tfh_tfd {
 /**
  * struct iwlagn_schedq_bc_tbl scheduler byte count table
  *	base physical address provided by SCD_DRAM_BASE_ADDR
+ * For devices up to a000:
  * @tfd_offset  0-12 - tx command byte count
- *	       12-16 - station index
+ *		12-16 - station index
+ * For a000 and on:
+ * @tfd_offset  0-12 - tx command byte count
+ *		12-13 - number of 64 byte chunks
+ *		14-16 - reserved
  */
 struct iwlagn_scd_bc_tbl {
 	__le16 tfd_offset[TFD_QUEUE_BC_SIZE];

drivers/net/wireless/intel/iwlwifi/pcie/tx.c

@@ -176,14 +176,14 @@ static void iwl_pcie_txq_stuck_timer(unsigned long data)
  * iwl_pcie_txq_update_byte_cnt_tbl - Set up entry in Tx byte-count array
  */
 static void iwl_pcie_txq_update_byte_cnt_tbl(struct iwl_trans *trans,
-					     struct iwl_txq *txq, u16 byte_cnt)
+					     struct iwl_txq *txq, u16 byte_cnt,
+					     int num_tbs)
 {
 	struct iwlagn_scd_bc_tbl *scd_bc_tbl;
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 	int write_ptr = txq->q.write_ptr;
 	int txq_id = txq->q.id;
 	u8 sec_ctl = 0;
-	u8 sta_id = 0;
 	u16 len = byte_cnt + IWL_TX_CRC_SIZE + IWL_TX_DELIMITER_SIZE;
 	__le16 bc_ent;
 	struct iwl_tx_cmd *tx_cmd =
@@ -191,7 +191,6 @@ static void iwl_pcie_txq_update_byte_cnt_tbl(struct iwl_trans *trans,
 
 	scd_bc_tbl = trans_pcie->scd_bc_tbls.addr;
 
-	sta_id = tx_cmd->sta_id;
 	sec_ctl = tx_cmd->sec_ctl;
 
 	switch (sec_ctl & TX_CMD_SEC_MSK) {
@@ -205,14 +204,32 @@ static void iwl_pcie_txq_update_byte_cnt_tbl(struct iwl_trans *trans,
 		len += IEEE80211_WEP_IV_LEN + IEEE80211_WEP_ICV_LEN;
 		break;
 	}
-
 	if (trans_pcie->bc_table_dword)
 		len = DIV_ROUND_UP(len, 4);
 
 	if (WARN_ON(len > 0xFFF || write_ptr >= TFD_QUEUE_SIZE_MAX))
 		return;
 
-	bc_ent = cpu_to_le16(len | (sta_id << 12));
+	if (trans->cfg->use_tfh) {
+		u8 filled_tfd_size = offsetof(struct iwl_tfh_tfd, tbs) +
+				     num_tbs * sizeof(struct iwl_tfh_tb);
+		/*
+		 * filled_tfd_size contains the number of filled bytes in the
+		 * TFD.
+		 * Dividing it by 64 will give the number of chunks to fetch
+		 * to SRAM- 0 for one chunk, 1 for 2 and so on.
+		 * If, for example, TFD contains only 3 TBs then 32 bytes
+		 * of the TFD are used, and only one chunk of 64 bytes should
+		 * be fetched
+		 */
+		u8 num_fetch_chunks = DIV_ROUND_UP(filled_tfd_size, 64) - 1;
+
+		bc_ent = cpu_to_le16(len | (num_fetch_chunks << 12));
+	} else {
+		u8 sta_id = tx_cmd->sta_id;
+
+		bc_ent = cpu_to_le16(len | (sta_id << 12));
+	}
 
 	scd_bc_tbl[txq_id].tfd_offset[write_ptr] = bc_ent;
 
@@ -240,6 +257,7 @@ static void iwl_pcie_txq_inval_byte_cnt_tbl(struct iwl_trans *trans,
 		sta_id = tx_cmd->sta_id;
 
 	bc_ent = cpu_to_le16(1 | (sta_id << 12));
+
 	scd_bc_tbl[txq_id].tfd_offset[read_ptr] = bc_ent;
 
 	if (read_ptr < TFD_QUEUE_SIZE_BC_DUP)
@@ -1126,7 +1144,8 @@ void iwl_trans_pcie_reclaim(struct iwl_trans *trans, int txq_id, int ssn,
 
 		txq->entries[txq->q.read_ptr].skb = NULL;
 
-		iwl_pcie_txq_inval_byte_cnt_tbl(trans, txq);
+		if (!trans->cfg->use_tfh)
+			iwl_pcie_txq_inval_byte_cnt_tbl(trans, txq);
 
 		iwl_pcie_txq_free_tfd(trans, txq);
 	}
@@ -2272,6 +2291,7 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 	struct iwl_queue *q;
 	dma_addr_t tb0_phys, tb1_phys, scratch_phys;
 	void *tb1_addr;
+	void *tfd;
 	u16 len, tb1_len;
 	bool wait_write_ptr;
 	__le16 fc;
@@ -2410,8 +2430,10 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 		goto out_err;
 	}
 
+	tfd = iwl_pcie_get_tfd(trans_pcie, txq, q->write_ptr);
 	/* Set up entry for this TFD in Tx byte-count array */
-	iwl_pcie_txq_update_byte_cnt_tbl(trans, txq, le16_to_cpu(tx_cmd->len));
+	iwl_pcie_txq_update_byte_cnt_tbl(trans, txq, le16_to_cpu(tx_cmd->len),
+					 iwl_pcie_tfd_get_num_tbs(trans, tfd));
 
 	wait_write_ptr = ieee80211_has_morefrags(fc);