net: ipa: don't have gsi_channel_update() return a value

If it finds no completed transactions, gsi_channel_trans_complete()
calls gsi_channel_update() to check hardware.  If new transactions
have completed, gsi_channel_update() records that, then calls
gsi_channel_trans_complete() to return the first of those found.
This recursion won't go any further, but can be avoided if we
have gsi_channel_update() only be responsible for updating state
after accessing hardware.

Change gsi_channel_update() so it simply checks for and handles
new completions, without returning a value.  If it needs to call
that function, have gsi_channel_trans_complete() determine whether
there are new transactions available after the update.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/gsi.c

@@ -1475,7 +1475,7 @@ void gsi_channel_doorbell(struct gsi_channel *channel)
 }
 
 /* Consult hardware, move any newly completed transactions to completed list */
-struct gsi_trans *gsi_channel_update(struct gsi_channel *channel)
+void gsi_channel_update(struct gsi_channel *channel)
 {
 	u32 evt_ring_id = channel->evt_ring_id;
 	struct gsi *gsi = channel->gsi;
@@ -1494,12 +1494,12 @@ struct gsi_trans *gsi_channel_update(struct gsi_channel *channel)
 	offset = GSI_EV_CH_E_CNTXT_4_OFFSET(evt_ring_id);
 	index = gsi_ring_index(ring, ioread32(gsi->virt + offset));
 	if (index == ring->index % ring->count)
-		return NULL;
+		return;
 
 	/* Get the transaction for the latest completed event. */
 	trans = gsi_event_trans(gsi, gsi_ring_virt(ring, index - 1));
 	if (!trans)
-		return NULL;
+		return;
 
 	/* For RX channels, update each completed transaction with the number
 	 * of bytes that were actually received.  For TX channels, report
@@ -1507,8 +1507,6 @@ struct gsi_trans *gsi_channel_update(struct gsi_channel *channel)
 	 * up the network stack.
 	 */
 	gsi_evt_ring_update(gsi, evt_ring_id, index);
-
-	return gsi_channel_trans_complete(channel);
 }
 
 /**

drivers/net/ipa/gsi_private.h

@@ -95,12 +95,12 @@ void gsi_channel_trans_exit(struct gsi_channel *channel);
 void gsi_channel_doorbell(struct gsi_channel *channel);
 
 /* gsi_channel_update() - Update knowledge of channel hardware state
- * @channel:	Channel whose doorbell should be rung
+ * @channel:	Channel to be updated
  *
  * Consult hardware, move any newly completed transactions to a
- * channel's completed list
+ * channel's completed list.
  */
-struct gsi_trans *gsi_channel_update(struct gsi_channel *channel);
+void gsi_channel_update(struct gsi_channel *channel);
 
 /**
  * gsi_ring_virt() - Return virtual address for a ring entry

drivers/net/ipa/gsi_trans.c

@@ -240,8 +240,11 @@ struct gsi_trans *gsi_channel_trans_complete(struct gsi_channel *channel)
 	struct gsi_trans_info *trans_info = &channel->trans_info;
 	u16 trans_id = trans_info->completed_id;
 
-	if (trans_id == trans_info->pending_id)
-		return gsi_channel_update(channel);
+	if (trans_id == trans_info->pending_id) {
+		gsi_channel_update(channel);
+		if (trans_id == trans_info->pending_id)
+			return NULL;
+	}
 
 	return &trans_info->trans[trans_id %= channel->tre_count];
 }