sfc: use efx_channel_tx_[old_]fill_level() in Siena/EF10 TX datapath

Instead of open-coding the calculation with efx_tx_queue_partner(), use
 the functions that iterate over numbers of queues other than 2 with
 efx_for_each_channel_tx_queue().
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/sfc/net_driver.h

@@ -1681,10 +1681,6 @@ efx_channel_tx_fill_level(struct efx_channel *channel)
 	struct efx_tx_queue *tx_queue;
 	unsigned int fill_level = 0;
 
-	/* This function is currently only used by EF100, which maybe
-	 * could do something simpler and just compute the fill level
-	 * of the single TXQ that's really in use.
-	 */
 	efx_for_each_channel_tx_queue(tx_queue, channel)
 		fill_level = max(fill_level,
 				 tx_queue->insert_count - tx_queue->read_count);

drivers/net/ethernet/sfc/tx.c

@@ -59,13 +59,12 @@ u8 *efx_tx_get_copy_buffer_limited(struct efx_tx_queue *tx_queue,
 
 static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
 {
-	/* We need to consider both queues that the net core sees as one */
-	struct efx_tx_queue *txq2 = efx_tx_queue_partner(txq1);
+	/* We need to consider all queues that the net core sees as one */
 	struct efx_nic *efx = txq1->efx;
+	struct efx_tx_queue *txq2;
 	unsigned int fill_level;
 
-	fill_level = max(txq1->insert_count - txq1->old_read_count,
-			 txq2->insert_count - txq2->old_read_count);
+	fill_level = efx_channel_tx_old_fill_level(txq1->channel);
 	if (likely(fill_level < efx->txq_stop_thresh))
 		return;
 
@@ -85,11 +84,10 @@ static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
 	 */
 	netif_tx_stop_queue(txq1->core_txq);
 	smp_mb();
-	txq1->old_read_count = READ_ONCE(txq1->read_count);
-	txq2->old_read_count = READ_ONCE(txq2->read_count);
+	efx_for_each_channel_tx_queue(txq2, txq1->channel)
+		txq2->old_read_count = READ_ONCE(txq2->read_count);
 
-	fill_level = max(txq1->insert_count - txq1->old_read_count,
-			 txq2->insert_count - txq2->old_read_count);
+	fill_level = efx_channel_tx_old_fill_level(txq1->channel);
 	EFX_WARN_ON_ONCE_PARANOID(fill_level >= efx->txq_entries);
 	if (likely(fill_level < efx->txq_stop_thresh)) {
 		smp_mb();

drivers/net/ethernet/sfc/tx_common.c

@@ -242,7 +242,6 @@ void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
 {
 	unsigned int fill_level, pkts_compl = 0, bytes_compl = 0;
 	struct efx_nic *efx = tx_queue->efx;
-	struct efx_tx_queue *txq2;
 
 	EFX_WARN_ON_ONCE_PARANOID(index > tx_queue->ptr_mask);
 
@@ -261,9 +260,7 @@ void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
 	if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) &&
 	    likely(efx->port_enabled) &&
 	    likely(netif_device_present(efx->net_dev))) {
-		txq2 = efx_tx_queue_partner(tx_queue);
-		fill_level = max(tx_queue->insert_count - tx_queue->read_count,
-				 txq2->insert_count - txq2->read_count);
+		fill_level = efx_channel_tx_fill_level(tx_queue->channel);
 		if (fill_level <= efx->txq_wake_thresh)
 			netif_tx_wake_queue(tx_queue->core_txq);
 	}