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| author | Nicolas Ferre <nicolas.ferre@atmel.com> | 2012-11-19 06:00:21 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-11-19 14:21:25 -0500 |
| commit | 909a85834d4e082501c26dd745b7caacf4eb1db3 (patch) | |
| tree | 5f92556445c6cea1485262d02658e11a3a3a7ff4 | |
| parent | e5ef39eda6a1dfc045445d1199e5508703d139df (diff) | |
| download | linux-3.10-909a85834d4e082501c26dd745b7caacf4eb1db3.tar.gz linux-3.10-909a85834d4e082501c26dd745b7caacf4eb1db3.tar.bz2 linux-3.10-909a85834d4e082501c26dd745b7caacf4eb1db3.zip | |
net/macb: move to circ_buf macros and fix initial condition
Move to circular buffers management macro and correct an error
with circular buffer initial condition.
Without this patch, the macb_tx_ring_avail() function was
not reporting the proper ring availability at startup:
macb macb: eth0: BUG! Tx Ring full when queue awake!
macb macb: eth0: tx_head = 0, tx_tail = 0
And hanginig forever...
I remove the macb_tx_ring_avail() function and use the
proven macros from circ_buf.h. CIRC_CNT() is used in the
"consumer" part of the driver: macb_tx_interrupt() to match
advice from Documentation/circular-buffers.txt.
Reported-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Tested-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/ethernet/cadence/macb.c | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c index edb2aba9045..27991ddb6ff 100644 --- a/drivers/net/ethernet/cadence/macb.c +++ b/drivers/net/ethernet/cadence/macb.c @@ -14,6 +14,7 @@ #include <linux/moduleparam.h> #include <linux/kernel.h> #include <linux/types.h> +#include <linux/circ_buf.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/gpio.h> @@ -38,8 +39,8 @@ #define TX_RING_SIZE 128 /* must be power of 2 */ #define TX_RING_BYTES (sizeof(struct macb_dma_desc) * TX_RING_SIZE) -/* minimum number of free TX descriptors before waking up TX process */ -#define MACB_TX_WAKEUP_THRESH (TX_RING_SIZE / 4) +/* level of occupied TX descriptors under which we wake up TX process */ +#define MACB_TX_WAKEUP_THRESH (3 * TX_RING_SIZE / 4) #define MACB_RX_INT_FLAGS (MACB_BIT(RCOMP) | MACB_BIT(RXUBR) \ | MACB_BIT(ISR_ROVR)) @@ -60,11 +61,6 @@ static unsigned int macb_tx_ring_wrap(unsigned int index) return index & (TX_RING_SIZE - 1); } -static unsigned int macb_tx_ring_avail(struct macb *bp) -{ - return (bp->tx_tail - bp->tx_head) & (TX_RING_SIZE - 1); -} - static struct macb_dma_desc *macb_tx_desc(struct macb *bp, unsigned int index) { return &bp->tx_ring[macb_tx_ring_wrap(index)]; @@ -524,7 +520,8 @@ static void macb_tx_interrupt(struct macb *bp) bp->tx_tail = tail; if (netif_queue_stopped(bp->dev) - && macb_tx_ring_avail(bp) > MACB_TX_WAKEUP_THRESH) + && CIRC_CNT(bp->tx_head, bp->tx_tail, + TX_RING_SIZE) <= MACB_TX_WAKEUP_THRESH) netif_wake_queue(bp->dev); } @@ -818,7 +815,7 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev) spin_lock_irqsave(&bp->lock, flags); /* This is a hard error, log it. */ - if (macb_tx_ring_avail(bp) < 1) { + if (CIRC_SPACE(bp->tx_head, bp->tx_tail, TX_RING_SIZE) < 1) { netif_stop_queue(dev); spin_unlock_irqrestore(&bp->lock, flags); netdev_err(bp->dev, "BUG! Tx Ring full when queue awake!\n"); @@ -855,7 +852,7 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev) macb_writel(bp, NCR, macb_readl(bp, NCR) | MACB_BIT(TSTART)); - if (macb_tx_ring_avail(bp) < 1) + if (CIRC_SPACE(bp->tx_head, bp->tx_tail, TX_RING_SIZE) < 1) netif_stop_queue(dev); spin_unlock_irqrestore(&bp->lock, flags); |