Commit d4ed8f8d authored by Linas Vepstas's avatar Linas Vepstas Committed by Jeff Garzik
Browse files

Spidernet DMA coalescing 



The current driver code performs 512 DMA mappings of a bunch of
32-byte ring descriptor structures. This is silly, as they are
all in contiguous memory. This patch changes the code to
dma_map_coherent() each rx/tx ring as a whole.

Signed-off-by: default avatarLinas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent 83432468

drivers/net/spider_net.c

+47 −56
Original line number Diff line number Diff line
@@ -280,72 +280,67 @@ spider_net_free_chain(struct spider_net_card *card, 
{

	struct spider_net_descr *descr;



	for (descr = chain->tail; !descr->bus_addr; descr = descr->next) {

		pci_unmap_single(card->pdev, descr->bus_addr,

				 SPIDER_NET_DESCR_SIZE, PCI_DMA_BIDIRECTIONAL);

	descr = chain->ring;

	do {

		descr->bus_addr = 0;

	}

		descr->next_descr_addr = 0;

		descr = descr->next;

	} while (descr != chain->ring);



	dma_free_coherent(&card->pdev->dev, chain->num_desc,

	    chain->ring, chain->dma_addr);

}



/**

 * spider_net_init_chain - links descriptor chain

 * spider_net_init_chain - alloc and link descriptor chain

 * @card: card structure

 * @chain: address of chain

 * @start_descr: address of descriptor array

 * @no: number of descriptors

 *

 * we manage a circular list that mirrors the hardware structure,

 * We manage a circular list that mirrors the hardware structure,

 * except that the hardware uses bus addresses.

 *

 * returns 0 on success, <0 on failure

 * Returns 0 on success, <0 on failure

 */

static int

spider_net_init_chain(struct spider_net_card *card,

		       struct spider_net_descr_chain *chain,

		       struct spider_net_descr *start_descr,

		       int no)

		       struct spider_net_descr_chain *chain)

{

	int i;

	struct spider_net_descr *descr;

	dma_addr_t buf;

	size_t alloc_size;



	descr = start_descr;

	memset(descr, 0, sizeof(*descr) * no);

	alloc_size = chain->num_desc * sizeof (struct spider_net_descr);



	/* set up the hardware pointers in each descriptor */

	for (i=0; i<no; i++, descr++) {

		descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;

	chain->ring = dma_alloc_coherent(&card->pdev->dev, alloc_size,

		&chain->dma_addr, GFP_KERNEL);



		buf = pci_map_single(card->pdev, descr,

				     SPIDER_NET_DESCR_SIZE,

				     PCI_DMA_BIDIRECTIONAL);

	if (!chain->ring)

		return -ENOMEM;



	descr = chain->ring;

	memset(descr, 0, alloc_size);



		if (pci_dma_mapping_error(buf))

			goto iommu_error;

	/* Set up the hardware pointers in each descriptor */

	buf = chain->dma_addr;

	for (i=0; i < chain->num_desc; i++, descr++) {

		descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;



		descr->bus_addr = buf;

		descr->next_descr_addr = 0;

		descr->next = descr + 1;

		descr->prev = descr - 1;



		buf += sizeof(struct spider_net_descr);

	}

	/* do actual circular list */

	(descr-1)->next = start_descr;

	start_descr->prev = descr-1;

	(descr-1)->next = chain->ring;

	chain->ring->prev = descr-1;



	spin_lock_init(&chain->lock);

	chain->head = start_descr;

	chain->tail = start_descr;



	chain->head = chain->ring;

	chain->tail = chain->ring;

	return 0;



iommu_error:

	descr = start_descr;

	for (i=0; i < no; i++, descr++)

		if (descr->bus_addr)

			pci_unmap_single(card->pdev, descr->bus_addr,

					 SPIDER_NET_DESCR_SIZE,

					 PCI_DMA_BIDIRECTIONAL);

	return -ENOMEM;

}



/**
@@ -707,7 +702,7 @@ spider_net_set_low_watermark(struct spider_net_card *card) 
	}



	/* If TX queue is short, don't even bother with interrupts */

	if (cnt < card->num_tx_desc/4)

	if (cnt < card->tx_chain.num_desc/4)

		return cnt;



	/* Set low-watermark 3/4th's of the way into the queue. */
@@ -1652,26 +1647,25 @@ spider_net_open(struct net_device *netdev) 
{

	struct spider_net_card *card = netdev_priv(netdev);

	struct spider_net_descr *descr;

	int i, result;

	int result;



	result = -ENOMEM;

	if (spider_net_init_chain(card, &card->tx_chain, card->descr,

	                          card->num_tx_desc))

	result = spider_net_init_chain(card, &card->tx_chain);

	if (result)

		goto alloc_tx_failed;



	card->low_watermark = NULL;



	/* rx_chain is after tx_chain, so offset is descr + tx_count */

	if (spider_net_init_chain(card, &card->rx_chain,

	                          card->descr + card->num_tx_desc,

	                          card->num_rx_desc))

	result = spider_net_init_chain(card, &card->rx_chain);

	if (result)

		goto alloc_rx_failed;



	descr = card->rx_chain.head;

	for (i=0; i < card->num_rx_desc; i++, descr++)

	/* Make a ring of of bus addresses */

	descr = card->rx_chain.ring;

	do {

		descr->next_descr_addr = descr->next->bus_addr;

		descr = descr->next;

	} while (descr != card->rx_chain.ring);



	/* allocate rx skbs */

	/* Allocate rx skbs */

	if (spider_net_alloc_rx_skbs(card))

		goto alloc_skbs_failed;
@@ -1924,6 +1918,7 @@ spider_net_stop(struct net_device *netdev) 


	/* release chains */

	spider_net_release_tx_chain(card, 1);

	spider_net_free_rx_chain_contents(card);



	spider_net_free_rx_chain_contents(card);
@@ -2057,8 +2052,8 @@ spider_net_setup_netdev(struct spider_net_card *card) 


	card->options.rx_csum = SPIDER_NET_RX_CSUM_DEFAULT;



	card->num_tx_desc = tx_descriptors;

	card->num_rx_desc = rx_descriptors;

	card->tx_chain.num_desc = tx_descriptors;

	card->rx_chain.num_desc = rx_descriptors;



	spider_net_setup_netdev_ops(netdev);
@@ -2107,12 +2102,8 @@ spider_net_alloc_card(void) 
{

	struct net_device *netdev;

	struct spider_net_card *card;

	size_t alloc_size;



	alloc_size = sizeof (*card) +

		sizeof (struct spider_net_descr) * rx_descriptors +

		sizeof (struct spider_net_descr) * tx_descriptors;

	netdev = alloc_etherdev(alloc_size);

	netdev = alloc_etherdev(sizeof(struct spider_net_card));

	if (!netdev)

		return NULL;

drivers/net/spider_net.h

+5 −12
Original line number Diff line number Diff line
@@ -378,6 +378,9 @@ struct spider_net_descr_chain { 
	spinlock_t lock;

	struct spider_net_descr *head;

	struct spider_net_descr *tail;

	struct spider_net_descr *ring;

	int num_desc;

	dma_addr_t dma_addr;

};



/* descriptor data_status bits */
@@ -397,8 +400,6 @@ struct spider_net_descr_chain { 
 * 701b8000 would be correct, but every packets gets that flag */

#define SPIDER_NET_DESTROY_RX_FLAGS	0x700b8000



#define SPIDER_NET_DESCR_SIZE		32



/* this will be bigger some time */

struct spider_net_options {

	int rx_csum; /* for rx: if 0 ip_summed=NONE,
@@ -441,25 +442,17 @@ struct spider_net_card { 
	struct spider_net_descr_chain rx_chain;

	struct spider_net_descr *low_watermark;



	struct net_device_stats netdev_stats;



	struct spider_net_options options;



	spinlock_t intmask_lock;

	struct tasklet_struct rxram_full_tl;

	struct timer_list tx_timer;



	struct work_struct tx_timeout_task;

	atomic_t tx_timeout_task_counter;

	wait_queue_head_t waitq;



	/* for ethtool */

	int msg_enable;

	int num_rx_desc;

	int num_tx_desc;

	struct net_device_stats netdev_stats;

	struct spider_net_extra_stats spider_stats;



	struct spider_net_descr descr[0];

	struct spider_net_options options;

};



#define pr_err(fmt,arg...) \

drivers/net/spider_net_ethtool.c

+2 −2
Original line number Diff line number Diff line
@@ -158,9 +158,9 @@ spider_net_ethtool_get_ringparam(struct net_device *netdev, 
	struct spider_net_card *card = netdev->priv;



	ering->tx_max_pending = SPIDER_NET_TX_DESCRIPTORS_MAX;

	ering->tx_pending = card->num_tx_desc;

	ering->tx_pending = card->tx_chain.num_desc;

	ering->rx_max_pending = SPIDER_NET_RX_DESCRIPTORS_MAX;

	ering->rx_pending = card->num_rx_desc;

	ering->rx_pending = card->rx_chain.num_desc;

}



static int spider_net_get_stats_count(struct net_device *netdev)

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