net: ipa: kill replenish_backlog

We no longer use the replenish_backlog atomic variable to decide
when we've got work to do providing receive buffers to hardware.
Basically, we try to keep the hardware as full as possible, all the
time.  We keep supplying buffers until the hardware has no more
space for them.

As a result, we can get rid of the replenish_backlog field and the
atomic operations performed on it.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/ipa_endpoint.c

@@ -1086,7 +1086,6 @@ static void ipa_endpoint_replenish(struct ipa_endpoint *endpoint)
 		return;
 
 	while ((trans = ipa_endpoint_trans_alloc(endpoint, 1))) {
-		WARN_ON(!atomic_dec_not_zero(&endpoint->replenish_backlog));
 		if (ipa_endpoint_replenish_one(endpoint, trans))
 			goto try_again_later;
 
@@ -1105,9 +1104,6 @@ static void ipa_endpoint_replenish(struct ipa_endpoint *endpoint)
 	gsi_trans_free(trans);
 	clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);
 
-	/* The last one didn't succeed, so fix the backlog */
-	atomic_inc(&endpoint->replenish_backlog);
-
 	/* Whenever a receive buffer transaction completes we'll try to
 	 * replenish again.  It's unlikely, but if we fail to supply even
 	 * one buffer, nothing will trigger another replenish attempt.
@@ -1346,7 +1342,6 @@ static void ipa_endpoint_rx_complete(struct ipa_endpoint *endpoint,
 	struct page *page;
 
 	ipa_endpoint_replenish(endpoint);
-	atomic_inc(&endpoint->replenish_backlog);
 
 	if (trans->cancelled)
 		return;
@@ -1693,8 +1688,6 @@ static void ipa_endpoint_setup_one(struct ipa_endpoint *endpoint)
 		 */
 		clear_bit(IPA_REPLENISH_ENABLED, endpoint->replenish_flags);
 		clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);
-		atomic_set(&endpoint->replenish_backlog,
-			   gsi_channel_tre_max(gsi, endpoint->channel_id));
 		INIT_DELAYED_WORK(&endpoint->replenish_work,
 				  ipa_endpoint_replenish_work);
 	}

drivers/net/ipa/ipa_endpoint.h

@@ -66,7 +66,6 @@ enum ipa_replenish_flag {
  * @netdev:		Network device pointer, if endpoint uses one
  * @replenish_flags:	Replenishing state flags
  * @replenish_ready:	Number of replenish transactions without doorbell
- * @replenish_backlog:	Number of buffers needed to fill hardware queue
  * @replenish_work:	Work item used for repeated replenish failures
  */
 struct ipa_endpoint {
@@ -86,7 +85,6 @@ struct ipa_endpoint {
 	/* Receive buffer replenishing for RX endpoints */
 	DECLARE_BITMAP(replenish_flags, IPA_REPLENISH_COUNT);
 	u32 replenish_ready;
-	atomic_t replenish_backlog;
 	struct delayed_work replenish_work;		/* global wq */
 };