[PATCH] net/macb: move to circ_buf macros and fix initial condition
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Mon Nov 19 10:33:57 EST 2012
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 <nicolas.ferre at atmel.com>
Just tested on 9260
Tested-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
Best Regards,
J.
> ---
> 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
>
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