sfc: Refactor queue teardown sequence to allow for EF10 flush behaviour

Currently efx_stop_datapath() will try to flush our DMA queues (if DMA
is enabled), then finalise software and hardware state for each queue.
However, for EF10 we must ask the MC to finalise each queue, which
implicitly starts flushing it, and then wait for the flush events.
We therefore need to delegate more of this to the NIC type.

Combine all the hardware operations into a new NIC-type operation
efx_nic_type::fini_dmaq, and call this before tearing down the
software state and buffers for all the DMA queues.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

drivers/net/ethernet/sfc/efx.c

@@ -640,7 +640,6 @@ static void efx_stop_datapath(struct efx_nic *efx)
 	struct efx_channel *channel;
 	struct efx_tx_queue *tx_queue;
 	struct efx_rx_queue *rx_queue;
-	struct pci_dev *dev = efx->pci_dev;
 	int rc;
 
 	EFX_ASSERT_RESET_SERIALISED(efx);
@@ -652,26 +651,6 @@ static void efx_stop_datapath(struct efx_nic *efx)
 			rx_queue->refill_enabled = false;
 	}
 
-	/* Only perform flush if dma is enabled */
-	if (dev->is_busmaster && efx->state != STATE_RECOVERY) {
-		rc = efx_nic_flush_queues(efx);
-
-		if (rc && EFX_WORKAROUND_7803(efx)) {
-			/* Schedule a reset to recover from the flush failure. The
-			 * descriptor caches reference memory we're about to free,
-			 * but falcon_reconfigure_mac_wrapper() won't reconnect
-			 * the MACs because of the pending reset. */
-			netif_err(efx, drv, efx->net_dev,
-				  "Resetting to recover from flush failure\n");
-			efx_schedule_reset(efx, RESET_TYPE_ALL);
-		} else if (rc) {
-			netif_err(efx, drv, efx->net_dev, "failed to flush queues\n");
-		} else {
-			netif_dbg(efx, drv, efx->net_dev,
-				  "successfully flushed all queues\n");
-		}
-	}
-
 	efx_for_each_channel(channel, efx) {
 		/* RX packet processing is pipelined, so wait for the
 		 * NAPI handler to complete.  At least event queue 0
@@ -683,7 +662,26 @@ static void efx_stop_datapath(struct efx_nic *efx)
 			efx_stop_eventq(channel);
 			efx_start_eventq(channel);
 		}
+	}
 
+	rc = efx->type->fini_dmaq(efx);
+	if (rc && EFX_WORKAROUND_7803(efx)) {
+		/* Schedule a reset to recover from the flush failure. The
+		 * descriptor caches reference memory we're about to free,
+		 * but falcon_reconfigure_mac_wrapper() won't reconnect
+		 * the MACs because of the pending reset.
+		 */
+		netif_err(efx, drv, efx->net_dev,
+			  "Resetting to recover from flush failure\n");
+		efx_schedule_reset(efx, RESET_TYPE_ALL);
+	} else if (rc) {
+		netif_err(efx, drv, efx->net_dev, "failed to flush queues\n");
+	} else {
+		netif_dbg(efx, drv, efx->net_dev,
+			  "successfully flushed all queues\n");
+	}
+
+	efx_for_each_channel(channel, efx) {
 		efx_for_each_channel_rx_queue(rx_queue, channel)
 			efx_fini_rx_queue(rx_queue);
 		efx_for_each_possible_channel_tx_queue(tx_queue, channel)

drivers/net/ethernet/sfc/efx.h

@@ -23,7 +23,6 @@ extern void efx_remove_tx_queue(struct efx_tx_queue *tx_queue);
 extern void efx_init_tx_queue(struct efx_tx_queue *tx_queue);
 extern void efx_init_tx_queue_core_txq(struct efx_tx_queue *tx_queue);
 extern void efx_fini_tx_queue(struct efx_tx_queue *tx_queue);
-extern void efx_release_tx_buffers(struct efx_tx_queue *tx_queue);
 extern netdev_tx_t
 efx_hard_start_xmit(struct sk_buff *skb, struct net_device *net_dev);
 extern netdev_tx_t

drivers/net/ethernet/sfc/falcon.c

@@ -2351,6 +2351,7 @@ const struct efx_nic_type falcon_a1_nic_type = {
 	.probe_port = falcon_probe_port,
 	.remove_port = falcon_remove_port,
 	.handle_global_event = falcon_handle_global_event,
+	.fini_dmaq = efx_farch_fini_dmaq,
 	.prepare_flush = falcon_prepare_flush,
 	.finish_flush = efx_port_dummy_op_void,
 	.update_stats = falcon_update_nic_stats,
@@ -2396,6 +2397,7 @@ const struct efx_nic_type falcon_b0_nic_type = {
 	.probe_port = falcon_probe_port,
 	.remove_port = falcon_remove_port,
 	.handle_global_event = falcon_handle_global_event,
+	.fini_dmaq = efx_farch_fini_dmaq,
 	.prepare_flush = falcon_prepare_flush,
 	.finish_flush = efx_port_dummy_op_void,
 	.update_stats = falcon_update_nic_stats,

drivers/net/ethernet/sfc/net_driver.h

@@ -953,8 +953,11 @@ static inline unsigned int efx_port_num(struct efx_nic *efx)
  * @probe_port: Probe the MAC and PHY
  * @remove_port: Free resources allocated by probe_port()
  * @handle_global_event: Handle a "global" event (may be %NULL)
+ * @fini_dmaq: Flush and finalise DMA queues (RX and TX queues)
  * @prepare_flush: Prepare the hardware for flushing the DMA queues
- * @finish_flush: Clean up after flushing the DMA queues
+ *	(for Falcon architecture)
+ * @finish_flush: Clean up after flushing the DMA queues (for Falcon
+ *	architecture)
  * @update_stats: Update statistics not provided by event handling
  * @start_stats: Start the regular fetching of statistics
  * @stop_stats: Stop the regular fetching of statistics
@@ -1014,6 +1017,7 @@ struct efx_nic_type {
 	int (*probe_port)(struct efx_nic *efx);
 	void (*remove_port)(struct efx_nic *efx);
 	bool (*handle_global_event)(struct efx_channel *channel, efx_qword_t *);
+	int (*fini_dmaq)(struct efx_nic *efx);
 	void (*prepare_flush)(struct efx_nic *efx);
 	void (*finish_flush)(struct efx_nic *efx);
 	void (*update_stats)(struct efx_nic *efx);

drivers/net/ethernet/sfc/nic.c

@@ -721,7 +721,7 @@ static bool efx_check_tx_flush_complete(struct efx_nic *efx)
 /* Flush all the transmit queues, and continue flushing receive queues until
  * they're all flushed. Wait for the DRAIN events to be recieved so that there
  * are no more RX and TX events left on any channel. */
-int efx_nic_flush_queues(struct efx_nic *efx)
+static int efx_farch_do_flush(struct efx_nic *efx)
 {
 	unsigned timeout = msecs_to_jiffies(5000); /* 5s for all flushes and drains */
 	struct efx_channel *channel;
@@ -729,8 +729,6 @@ int efx_nic_flush_queues(struct efx_nic *efx)
 	struct efx_tx_queue *tx_queue;
 	int rc = 0;
 
-	efx->type->prepare_flush(efx);
-
 	efx_for_each_channel(channel, efx) {
 		efx_for_each_channel_tx_queue(tx_queue, channel) {
 			atomic_inc(&efx->drain_pending);
@@ -791,7 +789,32 @@ int efx_nic_flush_queues(struct efx_nic *efx)
 		atomic_set(&efx->rxq_flush_outstanding, 0);
 	}
 
-	efx->type->finish_flush(efx);
+	return rc;
+}
+
+int efx_farch_fini_dmaq(struct efx_nic *efx)
+{
+	struct efx_channel *channel;
+	struct efx_tx_queue *tx_queue;
+	struct efx_rx_queue *rx_queue;
+	int rc = 0;
+
+	/* Do not attempt to write to the NIC during EEH recovery */
+	if (efx->state != STATE_RECOVERY) {
+		/* Only perform flush if DMA is enabled */
+		if (efx->pci_dev->is_busmaster) {
+			efx->type->prepare_flush(efx);
+			rc = efx_farch_do_flush(efx);
+			efx->type->finish_flush(efx);
+		}
+
+		efx_for_each_channel(channel, efx) {
+			efx_for_each_channel_rx_queue(rx_queue, channel)
+				efx_nic_fini_rx(rx_queue);
+			efx_for_each_channel_tx_queue(tx_queue, channel)
+				efx_nic_fini_tx(tx_queue);
+		}
+	}
 
 	return rc;
 }

drivers/net/ethernet/sfc/nic.h

@@ -260,14 +260,12 @@ extern int falcon_probe_board(struct efx_nic *efx, u16 revision_info);
 /* TX data path */
 extern int efx_nic_probe_tx(struct efx_tx_queue *tx_queue);
 extern void efx_nic_init_tx(struct efx_tx_queue *tx_queue);
-extern void efx_nic_fini_tx(struct efx_tx_queue *tx_queue);
 extern void efx_nic_remove_tx(struct efx_tx_queue *tx_queue);
 extern void efx_nic_push_buffers(struct efx_tx_queue *tx_queue);
 
 /* RX data path */
 extern int efx_nic_probe_rx(struct efx_rx_queue *rx_queue);
 extern void efx_nic_init_rx(struct efx_rx_queue *rx_queue);
-extern void efx_nic_fini_rx(struct efx_rx_queue *rx_queue);
 extern void efx_nic_remove_rx(struct efx_rx_queue *rx_queue);
 extern void efx_nic_notify_rx_desc(struct efx_rx_queue *rx_queue);
 extern void efx_nic_generate_fill_event(struct efx_rx_queue *rx_queue);
@@ -319,7 +317,7 @@ static inline int efx_nic_irq_test_irq_cpu(struct efx_nic *efx)
 }
 
 /* Global Resources */
-extern int efx_nic_flush_queues(struct efx_nic *efx);
+extern int efx_farch_fini_dmaq(struct efx_nic *efx);
 extern void siena_prepare_flush(struct efx_nic *efx);
 extern void siena_finish_flush(struct efx_nic *efx);
 extern void falcon_start_nic_stats(struct efx_nic *efx);

drivers/net/ethernet/sfc/rx.c

@@ -757,7 +757,6 @@ void efx_fini_rx_queue(struct efx_rx_queue *rx_queue)
 		  "shutting down RX queue %d\n", efx_rx_queue_index(rx_queue));
 
 	del_timer_sync(&rx_queue->slow_fill);
-	efx_nic_fini_rx(rx_queue);
 
 	/* Release RX buffers from the current read ptr to the write ptr */
 	if (rx_queue->buffer) {

drivers/net/ethernet/sfc/siena.c

@@ -685,6 +685,7 @@ const struct efx_nic_type siena_a0_nic_type = {
 	.reset = efx_mcdi_reset,
 	.probe_port = efx_mcdi_port_probe,
 	.remove_port = efx_mcdi_port_remove,
+	.fini_dmaq = efx_farch_fini_dmaq,
 	.prepare_flush = siena_prepare_flush,
 	.finish_flush = siena_finish_flush,
 	.update_stats = siena_update_nic_stats,

drivers/net/ethernet/sfc/tx.c

@@ -543,10 +543,13 @@ void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
 	tx_queue->initialised = true;
 }
 
-void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
+void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
 {
 	struct efx_tx_buffer *buffer;
 
+	netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
+		  "shutting down TX queue %d\n", tx_queue->queue);
+
 	if (!tx_queue->buffer)
 		return;
 
@@ -561,22 +564,6 @@ void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
 	netdev_tx_reset_queue(tx_queue->core_txq);
 }
 
-void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
-{
-	if (!tx_queue->initialised)
-		return;
-
-	netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
-		  "shutting down TX queue %d\n", tx_queue->queue);
-
-	tx_queue->initialised = false;
-
-	/* Flush TX queue, remove descriptor ring */
-	efx_nic_fini_tx(tx_queue);
-
-	efx_release_tx_buffers(tx_queue);
-}
-
 void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
 {
 	int i;