ath11k: add processor_id based ring_selector logic

Current ring selector logic follows round-robin scheduling,
when a process switch from one processor to another each time,
the data in the cache would have to be invalidated
and re-loaded from RAM leads to poor cache utilization.

Therefore smp_processor_id() attempt to keep processes
on the same processor via processor affinity which improves
cache utilization. Also, ring selection could be chosen round
robin when the processor_id based ring selection does not
have the resources.

Tested-on : IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-00874-QCAHKSWPL_SILICONZ-1
Signed-off-by: P Praneesh <ppranees@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1604914915-12831-1-git-send-email-ppranees@codeaurora.org

drivers/net/wireless/ath/ath11k/core.h

@@ -728,9 +728,6 @@ struct ath11k_base {
 	} stats;
 	u32 pktlog_defs_checksum;
 
-	/* Round robbin based TCL ring selector */
-	atomic_t tcl_ring_selector;
-
 	struct ath11k_dbring_cap *db_caps;
 	u32 num_db_cap;
 

drivers/net/wireless/ath/ath11k/dp_tx.c

@@ -105,14 +105,14 @@ int ath11k_dp_tx(struct ath11k *ar, struct ath11k_vif *arvif,
 
 	pool_id = skb_get_queue_mapping(skb) & (ATH11K_HW_MAX_QUEUES - 1);
 
-	/* Let the default ring selection be based on a round robin
-	 * fashion where one of the 3 tcl rings are selected based on
-	 * the tcl_ring_selector counter. In case that ring
+	/* Let the default ring selection be based on current processor
+	 * number, where one of the 3 tcl rings are selected based on
+	 * the smp_processor_id(). In case that ring
 	 * is full/busy, we resort to other available rings.
 	 * If all rings are full, we drop the packet.
 	 * //TODO Add throttling logic when all rings are full
 	 */
-	ring_selector = atomic_inc_return(&ab->tcl_ring_selector);
+	ring_selector = smp_processor_id();
 
 tcl_ring_sel:
 	tcl_ring_retry = false;