ath10k: minimize coherent dma accesses

It doesn't make much sense to calculate the ring
size fill count because it already is memoized in
a separate variable.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/htt_rx.c

@@ -225,12 +225,6 @@ static void ath10k_htt_rx_ring_refill_retry(unsigned long arg)
 	ath10k_htt_rx_msdu_buff_replenish(htt);
 }
 
-static unsigned ath10k_htt_rx_ring_elems(struct ath10k_htt *htt)
-{
-	return (__le32_to_cpu(*htt->rx_ring.alloc_idx.vaddr) -
-		htt->rx_ring.sw_rd_idx.msdu_payld) & htt->rx_ring.size_mask;
-}
-
 void ath10k_htt_rx_detach(struct ath10k_htt *htt)
 {
 	int sw_rd_idx = htt->rx_ring.sw_rd_idx.msdu_payld;
@@ -276,8 +270,10 @@ static inline struct sk_buff *ath10k_htt_rx_netbuf_pop(struct ath10k_htt *htt)
 
 	lockdep_assert_held(&htt->rx_ring.lock);
 
-	if (ath10k_htt_rx_ring_elems(htt) == 0)
-		ath10k_warn("htt rx ring is empty!\n");
+	if (htt->rx_ring.fill_cnt == 0) {
+		ath10k_warn("tried to pop sk_buff from an empty rx ring\n");
+		return NULL;
+	}
 
 	idx = htt->rx_ring.sw_rd_idx.msdu_payld;
 	msdu = htt->rx_ring.netbufs_ring[idx];
@@ -312,9 +308,6 @@ static int ath10k_htt_rx_amsdu_pop(struct ath10k_htt *htt,
 
 	lockdep_assert_held(&htt->rx_ring.lock);
 
-	if (ath10k_htt_rx_ring_elems(htt) == 0)
-		ath10k_warn("htt rx ring is empty!\n");
-
 	if (htt->rx_confused) {
 		ath10k_warn("htt is confused. refusing rx\n");
 		return 0;