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 <nicolas.fe...@atmel.com>
---
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
