Re: [PATCH] net/macb: move to circ_buf macros and fix initial condition
From: Jean-Christophe PLAGNIOL-VILLARD <hidden>
Date: 2012-11-19 16:00:56
Also in:
linux-arm-kernel, lkml
On 16:17 Mon 19 Nov , Nicolas Ferre wrote:
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>
Just tested on 9260 Tested-by: Jean-Christophe PLAGNIOL-VILLARD <redacted> Best Regards, J.
quoted hunk ↗ jump to hunk
--- 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