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Merge branch 'arc_emac'

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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2014-09-12 17:18:09 -04:00
commit dcbc0054d7
1 changed files with 37 additions and 16 deletions
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53
drivers/net/ethernet/arc/emac_main.c
View file

@ -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.
@ -180,10 +191,15 @@ 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))
netif_wake_queue(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);
}
/**
@ -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);