[PATCH] net/macb: move to circ_buf macros and fix initial condition
From: Nicolas Ferre <hidden>
Date: 2012-11-19 15:17:29
Also in:
linux-arm-kernel, lkml
Subsystem:
atmel macb ethernet driver, networking drivers, the rest · Maintainers:
Théo Lebrun, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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. Signed-off-by: Nicolas Ferre <redacted> --- drivers/net/ethernet/cadence/macb.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index edb2aba..27991dd 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);
--
1.8.0