[PATCH v8] bfin_mac: convert bfin Ethernet driver to NAPI framework

[PATCH v8] bfin_mac: convert bfin Ethernet driver to NAPI framework

[Sonic Zhang]

From: Sonic Zhang <sonic.zhang@analog.com>

Ethernet RX DMA buffers are polled in NAPI work queue other than received
directly in DMA RX interrupt handler.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>

---
v2-changes:
- avoid test NAPI_STATE_NPSVC bit in net device driver

v3-changes:
- use tabs while indenting the code

v4-changes:
- unconditionally complete the NAPI poll and re-enable the MAC_RX IRQ

v5-changes:
- should match open parenthesis

v6-changes:
- keep a count of bfin_mac_interrupt disabled mac_rx irq in the device private
area then call enable_irq in bfin_mac_poll

v7-changes:
- only IRQ disable when rx_irq_disabled is zero before the increment
and only do the IRQ enable when decrementing rx_irq_disabled will cause
it to become zero

v8-changes:
- disable mac rx irq for each call to napi poll in net poll loop and keep irq balanced
if netpoll scavenges between napi_schedule_prep and lp->rx_irq_disabled++
on a different CPU, bfin_mac_interrupt may later __napi_schedule while
already napi_completed in netpoll...bfin_mac_poll(): bfin_mac_poll won't
be run in net_rx_action and IRQ_MAC_RX will stay disabled.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
---
 drivers/net/ethernet/adi/bfin_mac.c | 79 +++++++++++++++++++++++--------------
 drivers/net/ethernet/adi/bfin_mac.h |  3 ++
 2 files changed, 52 insertions(+), 30 deletions(-)

diff --git a/drivers/net/ethernet/adi/bfin_mac.c b/drivers/net/ethernet/adi/bfin_mac.c
index 7ae74d4..c1f04aa 100644
--- a/drivers/net/ethernet/adi/bfin_mac.c
+++ b/drivers/net/ethernet/adi/bfin_mac.c
@@ -1218,11 +1218,11 @@ out:
 #define RX_ERROR_MASK (RX_LONG | RX_ALIGN | RX_CRC | RX_LEN | \
 	RX_FRAG | RX_ADDR | RX_DMAO | RX_PHY | RX_LATE | RX_RANGE)
 
-static void bfin_mac_rx(struct net_device *dev)
+static void bfin_mac_rx(struct bfin_mac_local *lp, int budget)
 {
+	struct net_device *dev = lp->ndev;
 	struct sk_buff *skb, *new_skb;
 	unsigned short len;
-	struct bfin_mac_local *lp __maybe_unused = netdev_priv(dev);
 #if defined(BFIN_MAC_CSUM_OFFLOAD)
 	unsigned int i;
 	unsigned char fcs[ETH_FCS_LEN + 1];
@@ -1256,7 +1256,7 @@ static void bfin_mac_rx(struct net_device *dev)
 	current_rx_ptr->skb = new_skb;
 	current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
 
-	len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
+	len = (unsigned short)(current_rx_ptr->status.status_word & RX_FRLEN);
 	/* Deduce Ethernet FCS length from Ethernet payload length */
 	len -= ETH_FCS_LEN;
 	skb_put(skb, len);
@@ -1294,7 +1294,8 @@ static void bfin_mac_rx(struct net_device *dev)
 	}
 #endif
 
-	netif_rx(skb);
+	napi_gro_receive(&lp->napi, skb);
+
 	dev->stats.rx_packets++;
 	dev->stats.rx_bytes += len;
 out:
@@ -1302,41 +1303,52 @@ out:
 	current_rx_ptr = current_rx_ptr->next;
 }
 
+static int bfin_mac_poll(struct napi_struct *napi, int budget)
+{
+	int i = 0;
+	struct bfin_mac_local *lp = container_of(napi,
+						 struct bfin_mac_local,
+						 napi);
+
+	while (current_rx_ptr->status.status_word != 0 && i < budget) {
+		bfin_mac_rx(lp, budget);
+		i++;
+	}
+
+	if (i < budget) {
+		napi_complete(napi);
+		if (test_and_clear_bit(BFIN_MAC_RX_IRQ_DISABLED, &lp->flags))
+			enable_irq(IRQ_MAC_RX);
+	}
+
+	return i;
+}
+
 /* interrupt routine to handle rx and error signal */
 static irqreturn_t bfin_mac_interrupt(int irq, void *dev_id)
 {
-	struct net_device *dev = dev_id;
-	int number = 0;
-
-get_one_packet:
-	if (current_rx_ptr->status.status_word == 0) {
-		/* no more new packet received */
-		if (number == 0) {
-			if (current_rx_ptr->next->status.status_word != 0) {
-				current_rx_ptr = current_rx_ptr->next;
-				goto real_rx;
-			}
-		}
-		bfin_write_DMA1_IRQ_STATUS(bfin_read_DMA1_IRQ_STATUS() |
-					   DMA_DONE | DMA_ERR);
-		return IRQ_HANDLED;
+	struct bfin_mac_local *lp = netdev_priv(dev_id);
+	u32 status;
+
+	status = bfin_read_DMA1_IRQ_STATUS();
+
+	bfin_write_DMA1_IRQ_STATUS(status | DMA_DONE | DMA_ERR);
+	if ((status & DMA_DONE)) {
+		disable_irq_nosync(IRQ_MAC_RX);
+		set_bit(BFIN_MAC_RX_IRQ_DISABLED, &lp->flags);
+		napi_schedule(&lp->napi);
 	}
 
-real_rx:
-	bfin_mac_rx(dev);
-	number++;
-	goto get_one_packet;
+	return IRQ_HANDLED;
 }
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
-static void bfin_mac_poll(struct net_device *dev)
+static void bfin_mac_poll_controller(struct net_device *dev)
 {
 	struct bfin_mac_local *lp = netdev_priv(dev);
 
-	disable_irq(IRQ_MAC_RX);
 	bfin_mac_interrupt(IRQ_MAC_RX, dev);
 	tx_reclaim_skb(lp);
-	enable_irq(IRQ_MAC_RX);
 }
 #endif				/* CONFIG_NET_POLL_CONTROLLER */
 
@@ -1428,14 +1440,13 @@ static void bfin_mac_timeout(struct net_device *dev)
 		tx_list_head = tx_list_head->next;
 	}
 
-	if (netif_queue_stopped(lp->ndev))
-		netif_wake_queue(lp->ndev);
+	if (netif_queue_stopped(dev))
+		netif_wake_queue(dev);
 
 	bfin_mac_enable(lp->phydev);
 
 	/* We can accept TX packets again */
 	dev->trans_start = jiffies; /* prevent tx timeout */
-	netif_wake_queue(dev);
 }
 
 static void bfin_mac_multicast_hash(struct net_device *dev)
@@ -1562,6 +1573,7 @@ static int bfin_mac_open(struct net_device *dev)
 		return ret;
 	pr_debug("hardware init finished\n");
 
+	napi_enable(&lp->napi);
 	netif_start_queue(dev);
 	netif_carrier_on(dev);
 
@@ -1579,6 +1591,7 @@ static int bfin_mac_close(struct net_device *dev)
 	pr_debug("%s: %s\n", dev->name, __func__);
 
 	netif_stop_queue(dev);
+	napi_disable(&lp->napi);
 	netif_carrier_off(dev);
 
 	phy_stop(lp->phydev);
@@ -1604,7 +1617,7 @@ static const struct net_device_ops bfin_mac_netdev_ops = {
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_change_mtu		= eth_change_mtu,
 #ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= bfin_mac_poll,
+	.ndo_poll_controller	= bfin_mac_poll_controller,
 #endif
 };
 
@@ -1689,6 +1702,9 @@ static int bfin_mac_probe(struct platform_device *pdev)
 	lp->tx_reclaim_timer.data = (unsigned long)lp;
 	lp->tx_reclaim_timer.function = tx_reclaim_skb_timeout;
 
+	lp->flags = 0;
+	netif_napi_add(ndev, &lp->napi, bfin_mac_poll, CONFIG_BFIN_RX_DESC_NUM);
+
 	spin_lock_init(&lp->lock);
 
 	/* now, enable interrupts */
@@ -1723,6 +1739,7 @@ out_err_phc:
 out_err_reg_ndev:
 	free_irq(IRQ_MAC_RX, ndev);
 out_err_request_irq:
+	netif_napi_del(&lp->napi);
 out_err_mii_probe:
 	mdiobus_unregister(lp->mii_bus);
 	mdiobus_free(lp->mii_bus);
@@ -1743,6 +1760,8 @@ static int bfin_mac_remove(struct platform_device *pdev)
 
 	unregister_netdev(ndev);
 
+	netif_napi_del(&lp->napi);
+
 	free_irq(IRQ_MAC_RX, ndev);
 
 	free_netdev(ndev);
diff --git a/drivers/net/ethernet/adi/bfin_mac.h b/drivers/net/ethernet/adi/bfin_mac.h
index 6dec86a..d1217db 100644
--- a/drivers/net/ethernet/adi/bfin_mac.h
+++ b/drivers/net/ethernet/adi/bfin_mac.h
@@ -26,6 +26,7 @@
 #endif
 
 #define TX_RECLAIM_JIFFIES (HZ / 5)
+#define BFIN_MAC_RX_IRQ_DISABLED	1
 
 struct dma_descriptor {
 	struct dma_descriptor *next_dma_desc;
@@ -80,6 +81,8 @@ struct bfin_mac_local {
 	int irq_wake_requested;
 	struct timer_list tx_reclaim_timer;
 	struct net_device *ndev;
+	struct napi_struct napi;
+	unsigned long flags;
 
 	/* Data for EMAC_VLAN1 regs */
 	u16 vlan1_mask, vlan2_mask;
-- 
1.8.2.3

Re: [PATCH v8] bfin_mac: convert bfin Ethernet driver to NAPI framework

[Eric Dumazet]

On Thu, 2014-07-24 at 16:39 +0800, Sonic Zhang wrote:
> From: Sonic Zhang <sonic.zhang@analog.com>
> 
> Ethernet RX DMA buffers are polled in NAPI work queue other than received
> directly in DMA RX interrupt handler.
> 


> ---
>  drivers/net/ethernet/adi/bfin_mac.c | 79 +++++++++++++++++++++++--------------
>  drivers/net/ethernet/adi/bfin_mac.h |  3 ++
>  2 files changed, 52 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/net/ethernet/adi/bfin_mac.c b/drivers/net/ethernet/adi/bfin_mac.c
> index 7ae74d4..c1f04aa 100644
> --- a/drivers/net/ethernet/adi/bfin_mac.c
> +++ b/drivers/net/ethernet/adi/bfin_mac.c
> @@ -1218,11 +1218,11 @@ out:
>  #define RX_ERROR_MASK (RX_LONG | RX_ALIGN | RX_CRC | RX_LEN | \
>  	RX_FRAG | RX_ADDR | RX_DMAO | RX_PHY | RX_LATE | RX_RANGE)
>  
> -static void bfin_mac_rx(struct net_device *dev)
> +static void bfin_mac_rx(struct bfin_mac_local *lp, int budget)

budget is not used in this function. (I already mentioned this)

>  {
> +	struct net_device *dev = lp->ndev;
>  	struct sk_buff *skb, *new_skb;
>  	unsigned short len;
> -	struct bfin_mac_local *lp __maybe_unused = netdev_priv(dev);
>  #if defined(BFIN_MAC_CSUM_OFFLOAD)
>  	unsigned int i;
>  	unsigned char fcs[ETH_FCS_LEN + 1];
> @@ -1256,7 +1256,7 @@ static void bfin_mac_rx(struct net_device *dev)
>  	current_rx_ptr->skb = new_skb;
>  	current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
>  
> -	len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
> +	len = (unsigned short)(current_rx_ptr->status.status_word & RX_FRLEN);
>  	/* Deduce Ethernet FCS length from Ethernet payload length */
>  	len -= ETH_FCS_LEN;
>  	skb_put(skb, len);
> @@ -1294,7 +1294,8 @@ static void bfin_mac_rx(struct net_device *dev)
>  	}
>  #endif
>  
> -	netif_rx(skb);
> +	napi_gro_receive(&lp->napi, skb);
> +
>  	dev->stats.rx_packets++;
>  	dev->stats.rx_bytes += len;
>  out:
> @@ -1302,41 +1303,52 @@ out:
>  	current_rx_ptr = current_rx_ptr->next;
>  }


> +	if ((status & DMA_DONE)) {
> +		disable_irq_nosync(IRQ_MAC_RX);
> +		set_bit(BFIN_MAC_RX_IRQ_DISABLED, &lp->flags);
> +		napi_schedule(&lp->napi);
>  	}

	No need for extra ()

	if (status & DMA_DONE) {
		...



>+       netif_napi_add(ndev, &lp->napi, bfin_mac_poll, CONFIG_BFIN_RX_DESC_NUM);


I already gave a feedback on this. Could you address it ?

Have you checked kernel log ?

You should have hit :

        if (weight > NAPI_POLL_WEIGHT)
                pr_err_once("netif_napi_add() called with weight %d on device %s\n",
                            weight, dev->name);

This is because CONFIG_BFIN_RX_DESC_NUM is 100, while NAPI_POLL_WEIGHT is 64.

Re: [PATCH v8] bfin_mac: convert bfin Ethernet driver to NAPI framework

[Sonic Zhang]

Hi Eric,

On Thu, Jul 24, 2014 at 5:13 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Thu, 2014-07-24 at 16:39 +0800, Sonic Zhang wrote:
>> From: Sonic Zhang <sonic.zhang@analog.com>
>>
>> Ethernet RX DMA buffers are polled in NAPI work queue other than received
>> directly in DMA RX interrupt handler.
>>
>
>
>> ---
>>  drivers/net/ethernet/adi/bfin_mac.c | 79 +++++++++++++++++++++++--------------
>>  drivers/net/ethernet/adi/bfin_mac.h |  3 ++
>>  2 files changed, 52 insertions(+), 30 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/adi/bfin_mac.c b/drivers/net/ethernet/adi/bfin_mac.c
>> index 7ae74d4..c1f04aa 100644
>> --- a/drivers/net/ethernet/adi/bfin_mac.c
>> +++ b/drivers/net/ethernet/adi/bfin_mac.c
>> @@ -1218,11 +1218,11 @@ out:
>>  #define RX_ERROR_MASK (RX_LONG | RX_ALIGN | RX_CRC | RX_LEN | \
>>       RX_FRAG | RX_ADDR | RX_DMAO | RX_PHY | RX_LATE | RX_RANGE)
>>
>> -static void bfin_mac_rx(struct net_device *dev)
>> +static void bfin_mac_rx(struct bfin_mac_local *lp, int budget)
>
> budget is not used in this function. (I already mentioned this)
OK

>
>>  {
>> +     struct net_device *dev = lp->ndev;
>>       struct sk_buff *skb, *new_skb;
>>       unsigned short len;
>> -     struct bfin_mac_local *lp __maybe_unused = netdev_priv(dev);
>>  #if defined(BFIN_MAC_CSUM_OFFLOAD)
>>       unsigned int i;
>>       unsigned char fcs[ETH_FCS_LEN + 1];
>> @@ -1256,7 +1256,7 @@ static void bfin_mac_rx(struct net_device *dev)
>>       current_rx_ptr->skb = new_skb;
>>       current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
>>
>> -     len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
>> +     len = (unsigned short)(current_rx_ptr->status.status_word & RX_FRLEN);
>>       /* Deduce Ethernet FCS length from Ethernet payload length */
>>       len -= ETH_FCS_LEN;
>>       skb_put(skb, len);
>> @@ -1294,7 +1294,8 @@ static void bfin_mac_rx(struct net_device *dev)
>>       }
>>  #endif
>>
>> -     netif_rx(skb);
>> +     napi_gro_receive(&lp->napi, skb);
>> +
>>       dev->stats.rx_packets++;
>>       dev->stats.rx_bytes += len;
>>  out:
>> @@ -1302,41 +1303,52 @@ out:
>>       current_rx_ptr = current_rx_ptr->next;
>>  }
>
>
>> +     if ((status & DMA_DONE)) {
>> +             disable_irq_nosync(IRQ_MAC_RX);
>> +             set_bit(BFIN_MAC_RX_IRQ_DISABLED, &lp->flags);
>> +             napi_schedule(&lp->napi);
>>       }
>
>         No need for extra ()
>
>         if (status & DMA_DONE) {
>                 ...
>

My typo.

>
>
>>+       netif_napi_add(ndev, &lp->napi, bfin_mac_poll, CONFIG_BFIN_RX_DESC_NUM);
>
>
> I already gave a feedback on this. Could you address it ?
>
> Have you checked kernel log ?
>
> You should have hit :
>
>         if (weight > NAPI_POLL_WEIGHT)
>                 pr_err_once("netif_napi_add() called with weight %d on device %s\n",
>                             weight, dev->name);
>
> This is because CONFIG_BFIN_RX_DESC_NUM is 100, while NAPI_POLL_WEIGHT is 64.
>

The default value of CONFIG_BFIN_RX_DESC_NUM is 20 in Kconfig. I will
set the range to 20 ~ 64.


Thank,

Sonic Zhang