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Commit dcbc0054 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'arc_emac' 



Beniamino Galvani says:

====================
net: arc_emac: fix tx issues

the patches below solve some issues found in the tx ring reclaim
strategy currently implemented in the arc_emac driver.

Without these patches a simple outgoing UDP flow blocks almost
immediately with the socket send buffer full, until some new rx
packets trigger a clean of the tx ring.

Everything seems to work fine on a Radxa Rock with this fix applied.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 1d7efe9d 74dd40bc

drivers/net/ethernet/arc/emac_main.c

+37 −16
Original line number Diff line number Diff line
@@ -29,6 +29,17 @@ 
#define DRV_NAME	"arc_emac"

#define DRV_VERSION	"1.0"



/**

 * arc_emac_tx_avail - Return the number of available slots in the tx ring.

 * @priv: Pointer to ARC EMAC private data structure.

 *

 * returns: the number of slots available for transmission in tx the ring.

 */

static inline int arc_emac_tx_avail(struct arc_emac_priv *priv)

{

	return (priv->txbd_dirty + TX_BD_NUM - priv->txbd_curr - 1) % TX_BD_NUM;

}



/**

 * arc_emac_adjust_link - Adjust the PHY link duplex.

 * @ndev:	Pointer to the net_device structure.
@@ -180,11 +191,16 @@ static void arc_emac_tx_clean(struct net_device *ndev) 
		txbd->info = 0;



		*txbd_dirty = (*txbd_dirty + 1) % TX_BD_NUM;

	}



		if (netif_queue_stopped(ndev))

	/* Ensure that txbd_dirty is visible to tx() before checking

	 * for queue stopped.

	 */

	smp_mb();



	if (netif_queue_stopped(ndev) && arc_emac_tx_avail(priv))

		netif_wake_queue(ndev);

}

}



/**

 * arc_emac_rx - processing of Rx packets.
@@ -298,7 +314,7 @@ static int arc_emac_poll(struct napi_struct *napi, int budget) 
	work_done = arc_emac_rx(ndev, budget);

	if (work_done < budget) {

		napi_complete(napi);

		arc_reg_or(priv, R_ENABLE, RXINT_MASK);

		arc_reg_or(priv, R_ENABLE, RXINT_MASK | TXINT_MASK);

	}



	return work_done;
@@ -327,9 +343,9 @@ static irqreturn_t arc_emac_intr(int irq, void *dev_instance) 
	/* Reset all flags except "MDIO complete" */

	arc_reg_set(priv, R_STATUS, status);



	if (status & RXINT_MASK) {

	if (status & (RXINT_MASK | TXINT_MASK)) {

		if (likely(napi_schedule_prep(&priv->napi))) {

			arc_reg_clr(priv, R_ENABLE, RXINT_MASK);

			arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK);

			__napi_schedule(&priv->napi);

		}

	}
@@ -440,7 +456,7 @@ static int arc_emac_open(struct net_device *ndev) 
	arc_reg_set(priv, R_TX_RING, (unsigned int)priv->txbd_dma);



	/* Enable interrupts */

	arc_reg_set(priv, R_ENABLE, RXINT_MASK | ERR_MASK);

	arc_reg_set(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);



	/* Set CONTROL */

	arc_reg_set(priv, R_CTRL,
@@ -511,7 +527,7 @@ static int arc_emac_stop(struct net_device *ndev) 
	netif_stop_queue(ndev);



	/* Disable interrupts */

	arc_reg_clr(priv, R_ENABLE, RXINT_MASK | ERR_MASK);

	arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);



	/* Disable EMAC */

	arc_reg_clr(priv, R_CTRL, EN_MASK);
@@ -574,11 +590,9 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev) 


	len = max_t(unsigned int, ETH_ZLEN, skb->len);



	/* EMAC still holds this buffer in its possession.

	 * CPU must not modify this buffer descriptor

	 */

	if (unlikely((le32_to_cpu(*info) & OWN_MASK) == FOR_EMAC)) {

	if (unlikely(!arc_emac_tx_avail(priv))) {

		netif_stop_queue(ndev);

		netdev_err(ndev, "BUG! Tx Ring full when queue awake!\n");

		return NETDEV_TX_BUSY;

	}
@@ -607,12 +621,19 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev) 
	/* Increment index to point to the next BD */

	*txbd_curr = (*txbd_curr + 1) % TX_BD_NUM;



	/* Get "info" of the next BD */

	info = &priv->txbd[*txbd_curr].info;

	/* Ensure that tx_clean() sees the new txbd_curr before

	 * checking the queue status. This prevents an unneeded wake

	 * of the queue in tx_clean().

	 */

	smp_mb();



	/* Check if if Tx BD ring is full - next BD is still owned by EMAC */

	if (unlikely((le32_to_cpu(*info) & OWN_MASK) == FOR_EMAC))

	if (!arc_emac_tx_avail(priv)) {

		netif_stop_queue(ndev);

		/* Refresh tx_dirty */

		smp_mb();

		if (arc_emac_tx_avail(priv))

			netif_start_queue(ndev);

	}



	arc_reg_set(priv, R_STATUS, TXPL_MASK);