[PATCH 21/21]: powerpc/cell spidernet DMA coalescing
From: Linas Vepstas
Date: Tue Oct 10 2006 - 17:23:47 EST
The current driver code performs 512 DMA mappns of a bunch of
32-byte structures. This is silly, as they are all in contiguous
memory. Ths patch changes the code to DMA map the entie area
with just one call.
Signed-off-by: Linas Vepstas <linas@xxxxxxxxxxxxxx>
Cc: James K Lewis <jklewis@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
----
drivers/net/spider_net.c | 107 +++++++++++++++++++++++------------------------
drivers/net/spider_net.h | 16 ++-----
2 files changed, 59 insertions(+), 64 deletions(-)
Index: linux-2.6.18-mm2/drivers/net/spider_net.c
===================================================================
--- linux-2.6.18-mm2.orig/drivers/net/spider_net.c 2006-10-10 13:40:56.000000000 -0500
+++ linux-2.6.18-mm2/drivers/net/spider_net.c 2006-10-10 13:42:12.000000000 -0500
@@ -267,25 +267,6 @@ spider_net_get_descr_status(struct spide
}
/**
- * spider_net_free_chain - free descriptor chain
- * @card: card structure
- * @chain: address of chain
- *
- */
-static void
-spider_net_free_chain(struct spider_net_card *card,
- struct spider_net_descr_chain *chain)
-{
- 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->bus_addr = 0;
- }
-}
-
-/**
* spider_net_init_chain - links descriptor chain
* @card: card structure
* @chain: address of chain
@@ -297,15 +278,15 @@ spider_net_free_chain(struct spider_net_
*
* returns 0 on success, <0 on failure
*/
-static int
+static void
spider_net_init_chain(struct spider_net_card *card,
struct spider_net_descr_chain *chain,
struct spider_net_descr *start_descr,
+ dma_addr_t buf,
int no)
{
int i;
struct spider_net_descr *descr;
- dma_addr_t buf;
descr = start_descr;
memset(descr, 0, sizeof(*descr) * no);
@@ -314,17 +295,12 @@ spider_net_init_chain(struct spider_net_
for (i=0; i<no; i++, descr++) {
descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
- buf = pci_map_single(card->pdev, descr,
- SPIDER_NET_DESCR_SIZE,
- PCI_DMA_BIDIRECTIONAL);
-
- if (pci_dma_mapping_error(buf))
- goto iommu_error;
-
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;
@@ -333,17 +309,6 @@ spider_net_init_chain(struct spider_net_
spin_lock_init(&chain->lock);
chain->head = start_descr;
chain->tail = start_descr;
-
- 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;
}
/**
@@ -1658,24 +1623,32 @@ spider_net_open(struct net_device *netde
{
struct spider_net_card *card = netdev_priv(netdev);
struct spider_net_descr *descr;
- int i, result;
+ int result = -ENOMEM;
- result = -ENOMEM;
- if (spider_net_init_chain(card, &card->tx_chain, card->descr,
- card->num_tx_desc))
- goto alloc_tx_failed;
+ card->descr_dma_addr = pci_map_single(card->pdev, card->descr,
+ (card->num_tx_desc+card->num_rx_desc)*sizeof(struct spider_net_descr),
+ PCI_DMA_BIDIRECTIONAL);
+ if (pci_dma_mapping_error(card->descr_dma_addr))
+ return -ENOMEM;
+
+ spider_net_init_chain(card, &card->tx_chain, card->descr,
+ card->descr_dma_addr,
+ card->num_tx_desc);
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,
+ spider_net_init_chain(card, &card->rx_chain,
card->descr + card->num_tx_desc,
- card->num_rx_desc))
- goto alloc_rx_failed;
+ card->descr_dma_addr
+ + card->num_tx_desc * sizeof(struct spider_net_descr),
+ card->num_rx_desc);
descr = card->rx_chain.head;
- for (i=0; i < card->num_rx_desc; i++, descr++)
+ do {
descr->next_descr_addr = descr->next->bus_addr;
+ descr = descr->next;
+ } while (descr != card->rx_chain.head);
/* allocate rx skbs */
if (spider_net_alloc_rx_skbs(card))
@@ -1701,10 +1674,21 @@ spider_net_open(struct net_device *netde
register_int_failed:
spider_net_free_rx_chain_contents(card);
alloc_skbs_failed:
- spider_net_free_chain(card, &card->rx_chain);
-alloc_rx_failed:
- spider_net_free_chain(card, &card->tx_chain);
-alloc_tx_failed:
+ descr = card->rx_chain.head;
+ do {
+ descr->bus_addr = 0;
+ descr = descr->next;
+ } while (descr != card->rx_chain.head);
+
+ descr = card->tx_chain.head;
+ do {
+ descr->bus_addr = 0;
+ descr = descr->next;
+ } while (descr != card->tx_chain.head);
+
+ pci_unmap_single(card->pdev, card->descr_dma_addr,
+ (card->num_tx_desc+card->num_rx_desc)*sizeof(struct spider_net_descr),
+ PCI_DMA_BIDIRECTIONAL);
return result;
}
@@ -1907,6 +1891,7 @@ int
spider_net_stop(struct net_device *netdev)
{
struct spider_net_card *card = netdev_priv(netdev);
+ struct spider_net_descr *descr;
tasklet_kill(&card->rxram_full_tl);
netif_poll_disable(netdev);
@@ -1930,9 +1915,23 @@ spider_net_stop(struct net_device *netde
/* release chains */
spider_net_release_tx_chain(card, 1);
+ spider_net_free_rx_chain_contents(card);
+
+ descr = card->rx_chain.head;
+ do {
+ descr->bus_addr = 0;
+ descr = descr->next;
+ } while (descr != card->rx_chain.head);
+
+ descr = card->tx_chain.head;
+ do {
+ descr->bus_addr = 0;
+ descr = descr->next;
+ } while (descr != card->tx_chain.head);
- spider_net_free_chain(card, &card->tx_chain);
- spider_net_free_chain(card, &card->rx_chain);
+ pci_unmap_single(card->pdev, card->descr_dma_addr,
+ (card->num_tx_desc+card->num_rx_desc)*sizeof(struct spider_net_descr),
+ PCI_DMA_BIDIRECTIONAL);
return 0;
}
Index: linux-2.6.18-mm2/drivers/net/spider_net.h
===================================================================
--- linux-2.6.18-mm2.orig/drivers/net/spider_net.h 2006-10-10 13:35:33.000000000 -0500
+++ linux-2.6.18-mm2/drivers/net/spider_net.h 2006-10-10 13:42:12.000000000 -0500
@@ -397,8 +397,6 @@ 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,
@@ -437,28 +435,26 @@ struct spider_net_card {
void __iomem *regs;
+ int num_rx_desc;
+ int num_tx_desc;
struct spider_net_descr_chain tx_chain;
struct spider_net_descr_chain rx_chain;
struct spider_net_descr *low_watermark;
+ dma_addr_t descr_dma_addr;
- 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_options options;
+ /* Must be last element in the structure */
struct spider_net_descr descr[0];
};
-
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