Merge branch 'axienet-napi-gro-support'

Robert Hancock says:

====================
NAPI/GRO support for axienet driver

Add support for NAPI and GRO receive in the Xilinx AXI Ethernet driver,
and some other related cleanups.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 266 insertions, 250 deletions

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 40108968b350..0f9c88dd1a4a 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -119,11 +119,11 @@
 #define XAXIDMA_IRQ_ERROR_MASK		0x00004000 /* Error interrupt */
 #define XAXIDMA_IRQ_ALL_MASK		0x00007000 /* All interrupts */
 
-/* Default TX/RX Threshold and waitbound values for SGDMA mode */
+/* Default TX/RX Threshold and delay timer values for SGDMA mode */
 #define XAXIDMA_DFT_TX_THRESHOLD	24
-#define XAXIDMA_DFT_TX_WAITBOUND	254
-#define XAXIDMA_DFT_RX_THRESHOLD	24
-#define XAXIDMA_DFT_RX_WAITBOUND	254
+#define XAXIDMA_DFT_TX_USEC		50
+#define XAXIDMA_DFT_RX_THRESHOLD	1
+#define XAXIDMA_DFT_RX_USEC		50
 
 #define XAXIDMA_BD_CTRL_TXSOF_MASK	0x08000000 /* First tx packet */
 #define XAXIDMA_BD_CTRL_TXEOF_MASK	0x04000000 /* Last tx packet */
@@ -385,6 +385,7 @@ struct axidma_bd {
  * @phy_node:	Pointer to device node structure
  * @phylink:	Pointer to phylink instance
  * @phylink_config: phylink configuration settings
+ * @napi:	NAPI control structure
  * @pcs_phy:	Reference to PCS/PMA PHY if used
  * @pcs:	phylink pcs structure for PCS PHY
  * @switch_x_sgmii: Whether switchable 1000BaseX/SGMII mode is enabled in the core
@@ -395,6 +396,7 @@ struct axidma_bd {
  * @regs_start: Resource start for axienet device addresses
  * @regs:	Base address for the axienet_local device address space
  * @dma_regs:	Base address for the axidma device address space
+ * @rx_dma_cr:  Nominal content of RX DMA control register
  * @dma_err_task: Work structure to process Axi DMA errors
  * @tx_irq:	Axidma TX IRQ number
  * @rx_irq:	Axidma RX IRQ number
@@ -423,7 +425,9 @@ struct axidma_bd {
  * @csum_offload_on_tx_path:	Stores the checksum selection on TX side.
  * @csum_offload_on_rx_path:	Stores the checksum selection on RX side.
  * @coalesce_count_rx:	Store the irq coalesce on RX side.
+ * @coalesce_usec_rx:	IRQ coalesce delay for RX
  * @coalesce_count_tx:	Store the irq coalesce on TX side.
+ * @coalesce_usec_tx:	IRQ coalesce delay for TX
  */
 struct axienet_local {
 	struct net_device *ndev;
@@ -434,6 +438,8 @@ struct axienet_local {
 	struct phylink *phylink;
 	struct phylink_config phylink_config;
 
+	struct napi_struct napi;
+
 	struct mdio_device *pcs_phy;
 	struct phylink_pcs pcs;
 
@@ -449,6 +455,8 @@ struct axienet_local {
 	void __iomem *regs;
 	void __iomem *dma_regs;
 
+	u32 rx_dma_cr;
+
 	struct work_struct dma_err_task;
 
 	int tx_irq;
@@ -476,7 +484,9 @@ struct axienet_local {
 	int csum_offload_on_rx_path;
 
 	u32 coalesce_count_rx;
+	u32 coalesce_usec_rx;
 	u32 coalesce_count_tx;
+	u32 coalesce_usec_tx;
 };
 
 /**
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 6eeaab77fbe0..1d8c6e910279 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -7,7 +7,7 @@
  * Copyright (c) 2008-2009 Secret Lab Technologies Ltd.
  * Copyright (c) 2010 - 2011 Michal Simek <monstr@monstr.eu>
  * Copyright (c) 2010 - 2011 PetaLogix
- * Copyright (c) 2019 SED Systems, a division of Calian Ltd.
+ * Copyright (c) 2019 - 2022 Calian Advanced Technologies
  * Copyright (c) 2010 - 2012 Xilinx, Inc. All rights reserved.
  *
  * This is a driver for the Xilinx Axi Ethernet which is used in the Virtex6
@@ -33,7 +33,7 @@
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
 #include <linux/skbuff.h>
-#include <linux/spinlock.h>
+#include <linux/math64.h>
 #include <linux/phy.h>
 #include <linux/mii.h>
 #include <linux/ethtool.h>
@@ -190,7 +190,7 @@ static void axienet_dma_bd_release(struct net_device *ndev)
 	struct axienet_local *lp = netdev_priv(ndev);
 
 	/* If we end up here, tx_bd_v must have been DMA allocated. */
-	dma_free_coherent(ndev->dev.parent,
+	dma_free_coherent(lp->dev,
 			  sizeof(*lp->tx_bd_v) * lp->tx_bd_num,
 			  lp->tx_bd_v,
 			  lp->tx_bd_p);
@@ -215,18 +215,90 @@ static void axienet_dma_bd_release(struct net_device *ndev)
 		 */
 		if (lp->rx_bd_v[i].cntrl) {
 			phys = desc_get_phys_addr(lp, &lp->rx_bd_v[i]);
-			dma_unmap_single(ndev->dev.parent, phys,
+			dma_unmap_single(lp->dev, phys,
 					 lp->max_frm_size, DMA_FROM_DEVICE);
 		}
 	}
 
-	dma_free_coherent(ndev->dev.parent,
+	dma_free_coherent(lp->dev,
 			  sizeof(*lp->rx_bd_v) * lp->rx_bd_num,
 			  lp->rx_bd_v,
 			  lp->rx_bd_p);
 }
 
 /**
+ * axienet_usec_to_timer - Calculate IRQ delay timer value
+ * @lp:		Pointer to the axienet_local structure
+ * @coalesce_usec: Microseconds to convert into timer value
+ */
+static u32 axienet_usec_to_timer(struct axienet_local *lp, u32 coalesce_usec)
+{
+	u32 result;
+	u64 clk_rate = 125000000; /* arbitrary guess if no clock rate set */
+
+	if (lp->axi_clk)
+		clk_rate = clk_get_rate(lp->axi_clk);
+
+	/* 1 Timeout Interval = 125 * (clock period of SG clock) */
+	result = DIV64_U64_ROUND_CLOSEST((u64)coalesce_usec * clk_rate,
+					 (u64)125000000);
+	if (result > 255)
+		result = 255;
+
+	return result;
+}
+
+/**
+ * axienet_dma_start - Set up DMA registers and start DMA operation
+ * @lp:		Pointer to the axienet_local structure
+ */
+static void axienet_dma_start(struct axienet_local *lp)
+{
+	u32 tx_cr;
+
+	/* Start updating the Rx channel control register */
+	lp->rx_dma_cr = (lp->coalesce_count_rx << XAXIDMA_COALESCE_SHIFT) |
+			XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_ERROR_MASK;
+	/* Only set interrupt delay timer if not generating an interrupt on
+	 * the first RX packet. Otherwise leave at 0 to disable delay interrupt.
+	 */
+	if (lp->coalesce_count_rx > 1)
+		lp->rx_dma_cr |= (axienet_usec_to_timer(lp, lp->coalesce_usec_rx)
+					<< XAXIDMA_DELAY_SHIFT) |
+				 XAXIDMA_IRQ_DELAY_MASK;
+	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, lp->rx_dma_cr);
+
+	/* Start updating the Tx channel control register */
+	tx_cr = (lp->coalesce_count_tx << XAXIDMA_COALESCE_SHIFT) |
+		XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_ERROR_MASK;
+	/* Only set interrupt delay timer if not generating an interrupt on
+	 * the first TX packet. Otherwise leave at 0 to disable delay interrupt.
+	 */
+	if (lp->coalesce_count_tx > 1)
+		tx_cr |= (axienet_usec_to_timer(lp, lp->coalesce_usec_tx)
+				<< XAXIDMA_DELAY_SHIFT) |
+			 XAXIDMA_IRQ_DELAY_MASK;
+	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, tx_cr);
+
+	/* Populate the tail pointer and bring the Rx Axi DMA engine out of
+	 * halted state. This will make the Rx side ready for reception.
+	 */
+	axienet_dma_out_addr(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
+	lp->rx_dma_cr |= XAXIDMA_CR_RUNSTOP_MASK;
+	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, lp->rx_dma_cr);
+	axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
+			     (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));
+
+	/* Write to the RS (Run-stop) bit in the Tx channel control register.
+	 * Tx channel is now ready to run. But only after we write to the
+	 * tail pointer register that the Tx channel will start transmitting.
+	 */
+	axienet_dma_out_addr(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
+	tx_cr |= XAXIDMA_CR_RUNSTOP_MASK;
+	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, tx_cr);
+}
+
+/**
  * axienet_dma_bd_init - Setup buffer descriptor rings for Axi DMA
  * @ndev:	Pointer to the net_device structure
  *
@@ -238,7 +310,6 @@ static void axienet_dma_bd_release(struct net_device *ndev)
  */
 static int axienet_dma_bd_init(struct net_device *ndev)
 {
-	u32 cr;
 	int i;
 	struct sk_buff *skb;
 	struct axienet_local *lp = netdev_priv(ndev);
@@ -249,13 +320,13 @@ static int axienet_dma_bd_init(struct net_device *ndev)
 	lp->rx_bd_ci = 0;
 
 	/* Allocate the Tx and Rx buffer descriptors. */
-	lp->tx_bd_v = dma_alloc_coherent(ndev->dev.parent,
+	lp->tx_bd_v = dma_alloc_coherent(lp->dev,
 					 sizeof(*lp->tx_bd_v) * lp->tx_bd_num,
 					 &lp->tx_bd_p, GFP_KERNEL);
 	if (!lp->tx_bd_v)
 		return -ENOMEM;
 
-	lp->rx_bd_v = dma_alloc_coherent(ndev->dev.parent,
+	lp->rx_bd_v = dma_alloc_coherent(lp->dev,
 					 sizeof(*lp->rx_bd_v) * lp->rx_bd_num,
 					 &lp->rx_bd_p, GFP_KERNEL);
 	if (!lp->rx_bd_v)
@@ -285,9 +356,9 @@ static int axienet_dma_bd_init(struct net_device *ndev)
 			goto out;
 
 		lp->rx_bd_v[i].skb = skb;
-		addr = dma_map_single(ndev->dev.parent, skb->data,
+		addr = dma_map_single(lp->dev, skb->data,
 				      lp->max_frm_size, DMA_FROM_DEVICE);
-		if (dma_mapping_error(ndev->dev.parent, addr)) {
+		if (dma_mapping_error(lp->dev, addr)) {
 			netdev_err(ndev, "DMA mapping error\n");
 			goto out;
 		}
@@ -296,50 +367,7 @@ static int axienet_dma_bd_init(struct net_device *ndev)
 		lp->rx_bd_v[i].cntrl = lp->max_frm_size;
 	}
 
-	/* Start updating the Rx channel control register */
-	cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	/* Update the interrupt coalesce count */
-	cr = ((cr & ~XAXIDMA_COALESCE_MASK) |
-	      ((lp->coalesce_count_rx) << XAXIDMA_COALESCE_SHIFT));
-	/* Update the delay timer count */
-	cr = ((cr & ~XAXIDMA_DELAY_MASK) |
-	      (XAXIDMA_DFT_RX_WAITBOUND << XAXIDMA_DELAY_SHIFT));
-	/* Enable coalesce, delay timer and error interrupts */
-	cr |= XAXIDMA_IRQ_ALL_MASK;
-	/* Write to the Rx channel control register */
-	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
-
-	/* Start updating the Tx channel control register */
-	cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	/* Update the interrupt coalesce count */
-	cr = (((cr & ~XAXIDMA_COALESCE_MASK)) |
-	      ((lp->coalesce_count_tx) << XAXIDMA_COALESCE_SHIFT));
-	/* Update the delay timer count */
-	cr = (((cr & ~XAXIDMA_DELAY_MASK)) |
-	      (XAXIDMA_DFT_TX_WAITBOUND << XAXIDMA_DELAY_SHIFT));
-	/* Enable coalesce, delay timer and error interrupts */
-	cr |= XAXIDMA_IRQ_ALL_MASK;
-	/* Write to the Tx channel control register */
-	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
-
-	/* Populate the tail pointer and bring the Rx Axi DMA engine out of
-	 * halted state. This will make the Rx side ready for reception.
-	 */
-	axienet_dma_out_addr(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
-	cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET,
-			  cr | XAXIDMA_CR_RUNSTOP_MASK);
-	axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
-			     (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));
-
-	/* Write to the RS (Run-stop) bit in the Tx channel control register.
-	 * Tx channel is now ready to run. But only after we write to the
-	 * tail pointer register that the Tx channel will start transmitting.
-	 */
-	axienet_dma_out_addr(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
-	cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET,
-			  cr | XAXIDMA_CR_RUNSTOP_MASK);
+	axienet_dma_start(lp);
 
 	return 0;
 out:
@@ -531,6 +559,44 @@ static int __axienet_device_reset(struct axienet_local *lp)
 }
 
 /**
+ * axienet_dma_stop - Stop DMA operation
+ * @lp:		Pointer to the axienet_local structure
+ */
+static void axienet_dma_stop(struct axienet_local *lp)
+{
+	int count;
+	u32 cr, sr;
+
+	cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
+	cr &= ~(XAXIDMA_CR_RUNSTOP_MASK | XAXIDMA_IRQ_ALL_MASK);
+	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
+	synchronize_irq(lp->rx_irq);
+
+	cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
+	cr &= ~(XAXIDMA_CR_RUNSTOP_MASK | XAXIDMA_IRQ_ALL_MASK);
+	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
+	synchronize_irq(lp->tx_irq);
+
+	/* Give DMAs a chance to halt gracefully */
+	sr = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
+	for (count = 0; !(sr & XAXIDMA_SR_HALT_MASK) && count < 5; ++count) {
+		msleep(20);
+		sr = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
+	}
+
+	sr = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
+	for (count = 0; !(sr & XAXIDMA_SR_HALT_MASK) && count < 5; ++count) {
+		msleep(20);
+		sr = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
+	}
+
+	/* Do a reset to ensure DMA is really stopped */
+	axienet_lock_mii(lp);
+	__axienet_device_reset(lp);
+	axienet_unlock_mii(lp);
+}
+
+/**
  * axienet_device_reset - Reset and initialize the Axi Ethernet hardware.
  * @ndev:	Pointer to the net_device structure
  *
@@ -636,7 +702,7 @@ static int axienet_free_tx_chain(struct net_device *ndev, u32 first_bd,
 		/* Ensure we see complete descriptor update */
 		dma_rmb();
 		phys = desc_get_phys_addr(lp, cur_p);
-		dma_unmap_single(ndev->dev.parent, phys,
+		dma_unmap_single(lp->dev, phys,
 				 (cur_p->cntrl & XAXIDMA_BD_CTRL_LENGTH_MASK),
 				 DMA_TO_DEVICE);
 
@@ -774,9 +840,9 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 		cur_p->app0 |= 2; /* Tx Full Checksum Offload Enabled */
 	}
 
-	phys = dma_map_single(ndev->dev.parent, skb->data,
+	phys = dma_map_single(lp->dev, skb->data,
 			      skb_headlen(skb), DMA_TO_DEVICE);
-	if (unlikely(dma_mapping_error(ndev->dev.parent, phys))) {
+	if (unlikely(dma_mapping_error(lp->dev, phys))) {
 		if (net_ratelimit())
 			netdev_err(ndev, "TX DMA mapping error\n");
 		ndev->stats.tx_dropped++;
@@ -790,11 +856,11 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 			lp->tx_bd_tail = 0;
 		cur_p = &lp->tx_bd_v[lp->tx_bd_tail];
 		frag = &skb_shinfo(skb)->frags[ii];
-		phys = dma_map_single(ndev->dev.parent,
+		phys = dma_map_single(lp->dev,
 				      skb_frag_address(frag),
 				      skb_frag_size(frag),
 				      DMA_TO_DEVICE);
-		if (unlikely(dma_mapping_error(ndev->dev.parent, phys))) {
+		if (unlikely(dma_mapping_error(lp->dev, phys))) {
 			if (net_ratelimit())
 				netdev_err(ndev, "TX DMA mapping error\n");
 			ndev->stats.tx_dropped++;
@@ -833,79 +899,84 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 }
 
 /**
- * axienet_recv - Is called from Axi DMA Rx Isr to complete the received
- *		  BD processing.
- * @ndev:	Pointer to net_device structure.
+ * axienet_poll - Triggered by RX ISR to complete the received BD processing.
+ * @napi:	Pointer to NAPI structure.
+ * @budget:	Max number of packets to process.
  *
- * This function is invoked from the Axi DMA Rx isr to process the Rx BDs. It
- * does minimal processing and invokes "netif_rx" to complete further
- * processing.
+ * Return: Number of RX packets processed.
  */
-static void axienet_recv(struct net_device *ndev)
+static int axienet_poll(struct napi_struct *napi, int budget)
 {
 	u32 length;
 	u32 csumstatus;
 	u32 size = 0;
-	u32 packets = 0;
+	int packets = 0;
 	dma_addr_t tail_p = 0;
-	struct axienet_local *lp = netdev_priv(ndev);
-	struct sk_buff *skb, *new_skb;
 	struct axidma_bd *cur_p;
+	struct sk_buff *skb, *new_skb;
+	struct axienet_local *lp = container_of(napi, struct axienet_local, napi);
 
 	cur_p = &lp->rx_bd_v[lp->rx_bd_ci];
 
-	while ((cur_p->status & XAXIDMA_BD_STS_COMPLETE_MASK)) {
+	while (packets < budget && (cur_p->status & XAXIDMA_BD_STS_COMPLETE_MASK)) {
 		dma_addr_t phys;
 
-		tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci;
-
 		/* Ensure we see complete descriptor update */
 		dma_rmb();
-		phys = desc_get_phys_addr(lp, cur_p);
-		dma_unmap_single(ndev->dev.parent, phys, lp->max_frm_size,
-				 DMA_FROM_DEVICE);
 
 		skb = cur_p->skb;
 		cur_p->skb = NULL;
-		length = cur_p->app4 & 0x0000FFFF;
-
-		skb_put(skb, length);
-		skb->protocol = eth_type_trans(skb, ndev);
-		/*skb_checksum_none_assert(skb);*/
-		skb->ip_summed = CHECKSUM_NONE;
-
-		/* if we're doing Rx csum offload, set it up */
-		if (lp->features & XAE_FEATURE_FULL_RX_CSUM) {
-			csumstatus = (cur_p->app2 &
-				      XAE_FULL_CSUM_STATUS_MASK) >> 3;
-			if ((csumstatus == XAE_IP_TCP_CSUM_VALIDATED) ||
-			    (csumstatus == XAE_IP_UDP_CSUM_VALIDATED)) {
-				skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+		/* skb could be NULL if a previous pass already received the
+		 * packet for this slot in the ring, but failed to refill it
+		 * with a newly allocated buffer. In this case, don't try to
+		 * receive it again.
+		 */
+		if (likely(skb)) {
+			length = cur_p->app4 & 0x0000FFFF;
+
+			phys = desc_get_phys_addr(lp, cur_p);
+			dma_unmap_single(lp->dev, phys, lp->max_frm_size,
+					 DMA_FROM_DEVICE);
+
+			skb_put(skb, length);
+			skb->protocol = eth_type_trans(skb, lp->ndev);
+			/*skb_checksum_none_assert(skb);*/
+			skb->ip_summed = CHECKSUM_NONE;
+
+			/* if we're doing Rx csum offload, set it up */
+			if (lp->features & XAE_FEATURE_FULL_RX_CSUM) {
+				csumstatus = (cur_p->app2 &
+					      XAE_FULL_CSUM_STATUS_MASK) >> 3;
+				if (csumstatus == XAE_IP_TCP_CSUM_VALIDATED ||
+				    csumstatus == XAE_IP_UDP_CSUM_VALIDATED) {
+					skb->ip_summed = CHECKSUM_UNNECESSARY;
+				}
+			} else if ((lp->features & XAE_FEATURE_PARTIAL_RX_CSUM) != 0 &&
+				   skb->protocol == htons(ETH_P_IP) &&
+				   skb->len > 64) {
+				skb->csum = be32_to_cpu(cur_p->app3 & 0xFFFF);
+				skb->ip_summed = CHECKSUM_COMPLETE;
 			}
-		} else if ((lp->features & XAE_FEATURE_PARTIAL_RX_CSUM) != 0 &&
-			   skb->protocol == htons(ETH_P_IP) &&
-			   skb->len > 64) {
-			skb->csum = be32_to_cpu(cur_p->app3 & 0xFFFF);
-			skb->ip_summed = CHECKSUM_COMPLETE;
-		}
 
-		netif_rx(skb);
+			napi_gro_receive(napi, skb);
 
-		size += length;
-		packets++;
+			size += length;
+			packets++;
+		}
 
-		new_skb = netdev_alloc_skb_ip_align(ndev, lp->max_frm_size);
+		new_skb = netdev_alloc_skb_ip_align(lp->ndev, lp->max_frm_size);
 		if (!new_skb)
-			return;
+			break;
 
-		phys = dma_map_single(ndev->dev.parent, new_skb->data,
+		phys = dma_map_single(lp->dev, new_skb->data,
 				      lp->max_frm_size,
 				      DMA_FROM_DEVICE);
-		if (unlikely(dma_mapping_error(ndev->dev.parent, phys))) {
+		if (unlikely(dma_mapping_error(lp->dev, phys))) {
 			if (net_ratelimit())
-				netdev_err(ndev, "RX DMA mapping error\n");
+				netdev_err(lp->ndev, "RX DMA mapping error\n");
 			dev_kfree_skb(new_skb);
-			return;
+			break;
 		}
 		desc_set_phys_addr(lp, phys, cur_p);
 
@@ -913,16 +984,30 @@ static void axienet_recv(struct net_device *ndev)
 		cur_p->status = 0;
 		cur_p->skb = new_skb;
 
+		/* Only update tail_p to mark this slot as usable after it has
+		 * been successfully refilled.
+		 */
+		tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci;
+
 		if (++lp->rx_bd_ci >= lp->rx_bd_num)
 			lp->rx_bd_ci = 0;
 		cur_p = &lp->rx_bd_v[lp->rx_bd_ci];
 	}
 
-	ndev->stats.rx_packets += packets;
-	ndev->stats.rx_bytes += size;
+	lp->ndev->stats.rx_packets += packets;
+	lp->ndev->stats.rx_bytes += size;
 
 	if (tail_p)
 		axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, tail_p);
+
+	if (packets < budget && napi_complete_done(napi, packets)) {
+		/* Re-enable RX completion interrupts. This should
+		 * cause an immediate interrupt if any RX packets are
+		 * already pending.
+		 */
+		axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, lp->rx_dma_cr);
+	}
+	return packets;
 }
 
 /**
@@ -937,41 +1022,27 @@ static void axienet_recv(struct net_device *ndev)
  */
 static irqreturn_t axienet_tx_irq(int irq, void *_ndev)
 {
-	u32 cr;
 	unsigned int status;
 	struct net_device *ndev = _ndev;
 	struct axienet_local *lp = netdev_priv(ndev);
 
 	status = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
-	if (status & (XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK)) {
-		axienet_dma_out32(lp, XAXIDMA_TX_SR_OFFSET, status);
-		axienet_start_xmit_done(lp->ndev);
-		goto out;
-	}
+
 	if (!(status & XAXIDMA_IRQ_ALL_MASK))
 		return IRQ_NONE;
-	if (status & XAXIDMA_IRQ_ERROR_MASK) {
-		dev_err(&ndev->dev, "DMA Tx error 0x%x\n", status);
-		dev_err(&ndev->dev, "Current BD is at: 0x%x%08x\n",
-			(lp->tx_bd_v[lp->tx_bd_ci]).phys_msb,
-			(lp->tx_bd_v[lp->tx_bd_ci]).phys);
-
-		cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-		/* Disable coalesce, delay timer and error interrupts */
-		cr &= (~XAXIDMA_IRQ_ALL_MASK);
-		/* Write to the Tx channel control register */
-		axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
-
-		cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-		/* Disable coalesce, delay timer and error interrupts */
-		cr &= (~XAXIDMA_IRQ_ALL_MASK);
-		/* Write to the Rx channel control register */
-		axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
 
+	axienet_dma_out32(lp, XAXIDMA_TX_SR_OFFSET, status);
+
+	if (unlikely(status & XAXIDMA_IRQ_ERROR_MASK)) {
+		netdev_err(ndev, "DMA Tx error 0x%x\n", status);
+		netdev_err(ndev, "Current BD is at: 0x%x%08x\n",
+			   (lp->tx_bd_v[lp->tx_bd_ci]).phys_msb,
+			   (lp->tx_bd_v[lp->tx_bd_ci]).phys);
 		schedule_work(&lp->dma_err_task);
-		axienet_dma_out32(lp, XAXIDMA_TX_SR_OFFSET, status);
+	} else {
+		axienet_start_xmit_done(lp->ndev);
 	}
-out:
+
 	return IRQ_HANDLED;
 }
 
@@ -982,46 +1053,40 @@ out:
  *
  * Return: IRQ_HANDLED if device generated a RX interrupt, IRQ_NONE otherwise.
  *
- * This is the Axi DMA Rx Isr. It invokes "axienet_recv" to complete the BD
+ * This is the Axi DMA Rx Isr. It invokes NAPI polling to complete the RX BD
  * processing.
  */
 static irqreturn_t axienet_rx_irq(int irq, void *_ndev)
 {
-	u32 cr;
 	unsigned int status;
 	struct net_device *ndev = _ndev;
 	struct axienet_local *lp = netdev_priv(ndev);
 
 	status = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
-	if (status & (XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK)) {
-		axienet_dma_out32(lp, XAXIDMA_RX_SR_OFFSET, status);
-		axienet_recv(lp->ndev);
-		goto out;
-	}
+
 	if (!(status & XAXIDMA_IRQ_ALL_MASK))
 		return IRQ_NONE;
-	if (status & XAXIDMA_IRQ_ERROR_MASK) {
-		dev_err(&ndev->dev, "DMA Rx error 0x%x\n", status);
-		dev_err(&ndev->dev, "Current BD is at: 0x%x%08x\n",
-			(lp->rx_bd_v[lp->rx_bd_ci]).phys_msb,
-			(lp->rx_bd_v[lp->rx_bd_ci]).phys);
-
-		cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-		/* Disable coalesce, delay timer and error interrupts */
-		cr &= (~XAXIDMA_IRQ_ALL_MASK);
-		/* Finally write to the Tx channel control register */
-		axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
-
-		cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-		/* Disable coalesce, delay timer and error interrupts */
-		cr &= (~XAXIDMA_IRQ_ALL_MASK);
-		/* write to the Rx channel control register */
-		axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
 
+	axienet_dma_out32(lp, XAXIDMA_RX_SR_OFFSET, status);
+
+	if (unlikely(status & XAXIDMA_IRQ_ERROR_MASK)) {
+		netdev_err(ndev, "DMA Rx error 0x%x\n", status);
+		netdev_err(ndev, "Current BD is at: 0x%x%08x\n",
+			   (lp->rx_bd_v[lp->rx_bd_ci]).phys_msb,
+			   (lp->rx_bd_v[lp->rx_bd_ci]).phys);
 		schedule_work(&lp->dma_err_task);
-		axienet_dma_out32(lp, XAXIDMA_RX_SR_OFFSET, status);
+	} else {
+		/* Disable further RX completion interrupts and schedule
+		 * NAPI receive.
+		 */
+		u32 cr = lp->rx_dma_cr;
+
+		cr &= ~(XAXIDMA_IRQ_IOC_MASK | XAXIDMA_IRQ_DELAY_MASK);
+		axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
+
+		napi_schedule(&lp->napi);
 	}
-out:
+
 	return IRQ_HANDLED;
 }
 
@@ -1095,6 +1160,8 @@ static int axienet_open(struct net_device *ndev)
 	/* Enable worker thread for Axi DMA error handling */
 	INIT_WORK(&lp->dma_err_task, axienet_dma_err_handler);
 
+	napi_enable(&lp->napi);
+
 	/* Enable interrupts for Axi DMA Tx */
 	ret = request_irq(lp->tx_irq, axienet_tx_irq, IRQF_SHARED,
 			  ndev->name, ndev);
@@ -1120,6 +1187,7 @@ err_eth_irq:
 err_rx_irq:
 	free_irq(lp->tx_irq, ndev);
 err_tx_irq:
+	napi_disable(&lp->napi);
 	phylink_stop(lp->phylink);
 	phylink_disconnect_phy(lp->phylink);
 	cancel_work_sync(&lp->dma_err_task);
@@ -1139,46 +1207,22 @@ err_tx_irq:
  */
 static int axienet_stop(struct net_device *ndev)
 {
-	u32 cr, sr;
-	int count;
 	struct axienet_local *lp = netdev_priv(ndev);
 
 	dev_dbg(&ndev->dev, "axienet_close()\n");
 
+	napi_disable(&lp->napi);
+
 	phylink_stop(lp->phylink);
 	phylink_disconnect_phy(lp->phylink);
 
 	axienet_setoptions(ndev, lp->options &
 			   ~(XAE_OPTION_TXEN | XAE_OPTION_RXEN));
 
-	cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	cr &= ~(XAXIDMA_CR_RUNSTOP_MASK | XAXIDMA_IRQ_ALL_MASK);
-	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
-
-	cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	cr &= ~(XAXIDMA_CR_RUNSTOP_MASK | XAXIDMA_IRQ_ALL_MASK);
-	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
+	axienet_dma_stop(lp);
 
 	axienet_iow(lp, XAE_IE_OFFSET, 0);
 
-	/* Give DMAs a chance to halt gracefully */
-	sr = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
-	for (count = 0; !(sr & XAXIDMA_SR_HALT_MASK) && count < 5; ++count) {
-		msleep(20);
-		sr = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
-	}
-
-	sr = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
-	for (count = 0; !(sr & XAXIDMA_SR_HALT_MASK) && count < 5; ++count) {
-		msleep(20);
-		sr = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
-	}
-
-	/* Do a reset to ensure DMA is really stopped */
-	axienet_lock_mii(lp);
-	__axienet_device_reset(lp);
-	axienet_unlock_mii(lp);
-
 	cancel_work_sync(&lp->dma_err_task);
 
 	if (lp->eth_irq > 0)
@@ -1449,14 +1493,12 @@ axienet_ethtools_get_coalesce(struct net_device *ndev,
 			      struct kernel_ethtool_coalesce *kernel_coal,
 			      struct netlink_ext_ack *extack)
 {
-	u32 regval = 0;
 	struct axienet_local *lp = netdev_priv(ndev);
-	regval = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	ecoalesce->rx_max_coalesced_frames = (regval & XAXIDMA_COALESCE_MASK)
-					     >> XAXIDMA_COALESCE_SHIFT;
-	regval = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	ecoalesce->tx_max_coalesced_frames = (regval & XAXIDMA_COALESCE_MASK)
-					     >> XAXIDMA_COALESCE_SHIFT;
+
+	ecoalesce->rx_max_coalesced_frames = lp->coalesce_count_rx;
+	ecoalesce->rx_coalesce_usecs = lp->coalesce_usec_rx;
+	ecoalesce->tx_max_coalesced_frames = lp->coalesce_count_tx;
+	ecoalesce->tx_coalesce_usecs = lp->coalesce_usec_tx;
 	return 0;
 }
 
@@ -1489,8 +1531,12 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
 
 	if (ecoalesce->rx_max_coalesced_frames)
 		lp->coalesce_count_rx = ecoalesce->rx_max_coalesced_frames;
+	if (ecoalesce->rx_coalesce_usecs)
+		lp->coalesce_usec_rx = ecoalesce->rx_coalesce_usecs;
 	if (ecoalesce->tx_max_coalesced_frames)
 		lp->coalesce_count_tx = ecoalesce->tx_max_coalesced_frames;
+	if (ecoalesce->tx_coalesce_usecs)
+		lp->coalesce_usec_tx = ecoalesce->tx_coalesce_usecs;
 
 	return 0;
 }
@@ -1521,7 +1567,8 @@ static int axienet_ethtools_nway_reset(struct net_device *dev)
 }
 
 static const struct ethtool_ops axienet_ethtool_ops = {
-	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES,
+	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
+				     ETHTOOL_COALESCE_USECS,
 	.get_drvinfo    = axienet_ethtools_get_drvinfo,
 	.get_regs_len   = axienet_ethtools_get_regs_len,
 	.get_regs       = axienet_ethtools_get_regs,
@@ -1678,29 +1725,26 @@ static const struct phylink_mac_ops axienet_phylink_ops = {
  */
 static void axienet_dma_err_handler(struct work_struct *work)
 {
+	u32 i;
 	u32 axienet_status;
-	u32 cr, i;
+	struct axidma_bd *cur_p;
 	struct axienet_local *lp = container_of(work, struct axienet_local,
 						dma_err_task);
 	struct net_device *ndev = lp->ndev;
-	struct axidma_bd *cur_p;
+
+	napi_disable(&lp->napi);
 
 	axienet_setoptions(ndev, lp->options &
 			   ~(XAE_OPTION_TXEN | XAE_OPTION_RXEN));
-	/* When we do an Axi Ethernet reset, it resets the complete core
-	 * including the MDIO. MDIO must be disabled before resetting.
-	 * Hold MDIO bus lock to avoid MDIO accesses during the reset.
-	 */
-	axienet_lock_mii(lp);
-	__axienet_device_reset(lp);
-	axienet_unlock_mii(lp);
+
+	axienet_dma_stop(lp);
 
 	for (i = 0; i < lp->tx_bd_num; i++) {
 		cur_p = &lp->tx_bd_v[i];
 		if (cur_p->cntrl) {
 			dma_addr_t addr = desc_get_phys_addr(lp, cur_p);
 
-			dma_unmap_single(ndev->dev.parent, addr,
+			dma_unmap_single(lp->dev, addr,
 					 (cur_p->cntrl &
 					  XAXIDMA_BD_CTRL_LENGTH_MASK),
 					 DMA_TO_DEVICE);
@@ -1733,50 +1777,7 @@ static void axienet_dma_err_handler(struct work_struct *work)
 	lp->tx_bd_tail = 0;
 	lp->rx_bd_ci = 0;
 
-	/* Start updating the Rx channel control register */
-	cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	/* Update the interrupt coalesce count */
-	cr = ((cr & ~XAXIDMA_COALESCE_MASK) |
-	      (XAXIDMA_DFT_RX_THRESHOLD << XAXIDMA_COALESCE_SHIFT));
-	/* Update the delay timer count */
-	cr = ((cr & ~XAXIDMA_DELAY_MASK) |
-	      (XAXIDMA_DFT_RX_WAITBOUND << XAXIDMA_DELAY_SHIFT));
-	/* Enable coalesce, delay timer and error interrupts */
-	cr |= XAXIDMA_IRQ_ALL_MASK;
-	/* Finally write to the Rx channel control register */
-	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, cr);
-
-	/* Start updating the Tx channel control register */
-	cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	/* Update the interrupt coalesce count */
-	cr = (((cr & ~XAXIDMA_COALESCE_MASK)) |
-	      (XAXIDMA_DFT_TX_THRESHOLD << XAXIDMA_COALESCE_SHIFT));
-	/* Update the delay timer count */
-	cr = (((cr & ~XAXIDMA_DELAY_MASK)) |
-	      (XAXIDMA_DFT_TX_WAITBOUND << XAXIDMA_DELAY_SHIFT));
-	/* Enable coalesce, delay timer and error interrupts */
-	cr |= XAXIDMA_IRQ_ALL_MASK;
-	/* Finally write to the Tx channel control register */
-	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, cr);
-
-	/* Populate the tail pointer and bring the Rx Axi DMA engine out of
-	 * halted state. This will make the Rx side ready for reception.
-	 */
-	axienet_dma_out_addr(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
-	cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET,
-			  cr | XAXIDMA_CR_RUNSTOP_MASK);
-	axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
-			     (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));
-
-	/* Write to the RS (Run-stop) bit in the Tx channel control register.
-	 * Tx channel is now ready to run. But only after we write to the
-	 * tail pointer register that the Tx channel will start transmitting
-	 */
-	axienet_dma_out_addr(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
-	cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET,
-			  cr | XAXIDMA_CR_RUNSTOP_MASK);
+	axienet_dma_start(lp);
 
 	axienet_status = axienet_ior(lp, XAE_RCW1_OFFSET);
 	axienet_status &= ~XAE_RCW1_RX_MASK;
@@ -1797,6 +1798,7 @@ static void axienet_dma_err_handler(struct work_struct *work)
 	axienet_set_mac_address(ndev, NULL);
 	axienet_set_multicast_list(ndev);
 	axienet_setoptions(ndev, lp->options);
+	napi_enable(&lp->napi);
 }
 
 /**
@@ -1845,6 +1847,8 @@ static int axienet_probe(struct platform_device *pdev)
 	lp->rx_bd_num = RX_BD_NUM_DEFAULT;
 	lp->tx_bd_num = TX_BD_NUM_DEFAULT;
 
+	netif_napi_add(ndev, &lp->napi, axienet_poll, NAPI_POLL_WEIGHT);
+
 	lp->axi_clk = devm_clk_get_optional(&pdev->dev, "s_axi_lite_clk");
 	if (!lp->axi_clk) {
 		/* For backward compatibility, if named AXI clock is not present,
@@ -2051,7 +2055,9 @@ static int axienet_probe(struct platform_device *pdev)
 	}
 
 	lp->coalesce_count_rx = XAXIDMA_DFT_RX_THRESHOLD;
+	lp->coalesce_usec_rx = XAXIDMA_DFT_RX_USEC;
 	lp->coalesce_count_tx = XAXIDMA_DFT_TX_THRESHOLD;
+	lp->coalesce_usec_tx = XAXIDMA_DFT_TX_USEC;
 
 	/* Reset core now that clocks are enabled, prior to accessing MDIO */
 	ret = __axienet_device_reset(lp);