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Commit 66d06757 authored by Petri Gynther's avatar Petri Gynther Committed by David S. Miller
Browse files

net: bcmgenet: simplify __bcmgenet_tx_reclaim() 



1. Use c_index and ring->c_index to determine how many TxCBs/TxBDs are
   ready for cleanup
   - c_index = the current value of TDMA_CONS_INDEX
   - TDMA_CONS_INDEX is HW-incremented and auto-wraparound (0x0-0xFFFF)
   - ring->c_index = __bcmgenet_tx_reclaim() cleaned up to this point on
     the previous invocation

2. Add bcmgenet_tx_ring->clean_ptr
   - index of the next TxCB to be cleaned
   - incremented as TxCBs/TxBDs are processed
   - value always in range [ring->cb_ptr, ring->end_ptr]

3. Fix incrementing of dev->stats.tx_packets
   - should be incremented only when tx_cb_ptr->skb != NULL

These changes simplify __bcmgenet_tx_reclaim(). Furthermore, Tx ring size
can now be any value.

With the old code, Tx ring size had to be a power-of-2:
   num_tx_bds = ring->size;
   c_index &= (num_tx_bds - 1);
   last_c_index &= (num_tx_bds - 1);

Signed-off-by: default avatarPetri Gynther <pgynther@google.com>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f93eb4ba

drivers/net/ethernet/broadcom/genet/bcmgenet.c

+21 −24
Original line number Diff line number Diff line
@@ -978,39 +978,32 @@ static unsigned int __bcmgenet_tx_reclaim(struct net_device *dev, 
					  struct bcmgenet_tx_ring *ring)

{

	struct bcmgenet_priv *priv = netdev_priv(dev);

	int last_tx_cn, last_c_index, num_tx_bds;

	struct enet_cb *tx_cb_ptr;

	struct netdev_queue *txq;

	unsigned int pkts_compl = 0;

	unsigned int bds_compl;

	unsigned int c_index;

	unsigned int txbds_ready;

	unsigned int txbds_processed = 0;



	/* Compute how many buffers are transmitted since last xmit call */

	c_index = bcmgenet_tdma_ring_readl(priv, ring->index, TDMA_CONS_INDEX);

	txq = netdev_get_tx_queue(dev, ring->queue);



	last_c_index = ring->c_index;

	num_tx_bds = ring->size;



	c_index &= (num_tx_bds - 1);

	c_index &= DMA_C_INDEX_MASK;



	if (c_index >= last_c_index)

		last_tx_cn = c_index - last_c_index;

	if (likely(c_index >= ring->c_index))

		txbds_ready = c_index - ring->c_index;

	else

		last_tx_cn = num_tx_bds - last_c_index + c_index;

		txbds_ready = (DMA_C_INDEX_MASK + 1) - ring->c_index + c_index;



	netif_dbg(priv, tx_done, dev,

		  "%s ring=%d index=%d last_tx_cn=%d last_index=%d\n",

		  __func__, ring->index,

		  c_index, last_tx_cn, last_c_index);

		  "%s ring=%d old_c_index=%u c_index=%u txbds_ready=%u\n",

		  __func__, ring->index, ring->c_index, c_index, txbds_ready);



	/* Reclaim transmitted buffers */

	while (last_tx_cn-- > 0) {

		tx_cb_ptr = ring->cbs + last_c_index;

		bds_compl = 0;

	while (txbds_processed < txbds_ready) {

		tx_cb_ptr = &priv->tx_cbs[ring->clean_ptr];

		if (tx_cb_ptr->skb) {

			pkts_compl++;

			bds_compl = skb_shinfo(tx_cb_ptr->skb)->nr_frags + 1;

			dev->stats.tx_packets++;

			dev->stats.tx_bytes += tx_cb_ptr->skb->len;

			dma_unmap_single(&dev->dev,

					 dma_unmap_addr(tx_cb_ptr, dma_addr),
@@ -1026,20 +1019,23 @@ static unsigned int __bcmgenet_tx_reclaim(struct net_device *dev, 
				       DMA_TO_DEVICE);

			dma_unmap_addr_set(tx_cb_ptr, dma_addr, 0);

		}

		dev->stats.tx_packets++;

		ring->free_bds += bds_compl;



		last_c_index++;

		last_c_index &= (num_tx_bds - 1);

		txbds_processed++;

		if (likely(ring->clean_ptr < ring->end_ptr))

			ring->clean_ptr++;

		else

			ring->clean_ptr = ring->cb_ptr;

	}



	ring->free_bds += txbds_processed;

	ring->c_index = (ring->c_index + txbds_processed) & DMA_C_INDEX_MASK;



	if (ring->free_bds > (MAX_SKB_FRAGS + 1)) {

		txq = netdev_get_tx_queue(dev, ring->queue);

		if (netif_tx_queue_stopped(txq))

			netif_tx_wake_queue(txq);

	}



	ring->c_index = c_index;



	return pkts_compl;

}
@@ -1734,6 +1730,7 @@ static void bcmgenet_init_tx_ring(struct bcmgenet_priv *priv, 
	}

	ring->cbs = priv->tx_cbs + start_ptr;

	ring->size = size;

	ring->clean_ptr = start_ptr;

	ring->c_index = 0;

	ring->free_bds = size;

	ring->write_ptr = start_ptr;

drivers/net/ethernet/broadcom/genet/bcmgenet.h

+1 −0
Original line number Diff line number Diff line
@@ -525,6 +525,7 @@ struct bcmgenet_tx_ring { 
	unsigned int	queue;		/* queue index */

	struct enet_cb	*cbs;		/* tx ring buffer control block*/

	unsigned int	size;		/* size of each tx ring */

	unsigned int    clean_ptr;      /* Tx ring clean pointer */

	unsigned int	c_index;	/* last consumer index of each ring*/

	unsigned int	free_bds;	/* # of free bds for each ring */

	unsigned int	write_ptr;	/* Tx ring write pointer SW copy */