iwlwifi: pcie: use shadow registers for updating write pointer

The RX queues have a shadow register for the write pointer
that enables updates without grabbing NIC access. Use them
instead of the periphery registers because accessing those
is much more expensive.
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

@@ -321,6 +321,9 @@ static inline unsigned int FH_MEM_CBBC_QUEUE(unsigned int chnl)
 /* Write index table */
 #define RFH_Q0_FRBDCB_WIDX 0xA08080
 #define RFH_Q_FRBDCB_WIDX(q) (RFH_Q0_FRBDCB_WIDX + (q) * 4)
+/* Write index table - shadow registers */
+#define RFH_Q0_FRBDCB_WIDX_TRG 0x1C80
+#define RFH_Q_FRBDCB_WIDX_TRG(q) (RFH_Q0_FRBDCB_WIDX_TRG + (q) * 4)
 /* Read index table */
 #define RFH_Q0_FRBDCB_RIDX 0xA080C0
 #define RFH_Q_FRBDCB_RIDX(q) (RFH_Q0_FRBDCB_RIDX + (q) * 4)

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

@@ -208,7 +208,7 @@ static void iwl_pcie_rxq_inc_wr_ptr(struct iwl_trans *trans,
 
 	rxq->write_actual = round_down(rxq->write, 8);
 	if (trans->cfg->mq_rx_supported)
-		iwl_write_prph(trans, RFH_Q_FRBDCB_WIDX(rxq->id),
+		iwl_write32(trans, RFH_Q_FRBDCB_WIDX_TRG(rxq->id),
 			    rxq->write_actual);
 	/*
 	 * write to FH_RSCSR_CHNL0_WPTR register even in MQ as a W/A to