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tg3: Clarify rx buffer relationships

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This patch attempts to document the various rx buffer sizes used by the
driver and how they relate to each other.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Matt Carlson 2009-08-28 13:58:46 +00:00 committed by David S. Miller
parent 8f666b07ac
commit 287be12e17
2 changed files with 24 additions and 20 deletions
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42
drivers/net/tg3.c
View File

@ -125,8 +125,15 @@
TG3_TX_RING_SIZE)
#define NEXT_TX(N) (((N) + 1) & (TG3_TX_RING_SIZE - 1))
#define RX_PKT_BUF_SZ (1536 + tp->rx_offset + 64)
#define RX_JUMBO_PKT_BUF_SZ (9046 + tp->rx_offset + 64)
#define TG3_DMA_BYTE_ENAB 64
#define TG3_RX_STD_DMA_SZ 1536
#define TG3_RX_JMB_DMA_SZ 9046
#define TG3_RX_DMA_TO_MAP_SZ(x) ((x) + TG3_DMA_BYTE_ENAB)
#define TG3_RX_STD_MAP_SZ TG3_RX_DMA_TO_MAP_SZ(TG3_RX_STD_DMA_SZ)
#define TG3_RX_JMB_MAP_SZ TG3_RX_DMA_TO_MAP_SZ(TG3_RX_JMB_DMA_SZ)
/* minimum number of free TX descriptors required to wake up TX process */
#define TG3_TX_WAKEUP_THRESH(tp) ((tp)->tx_pending / 4)
@ -4354,7 +4361,7 @@ static int tg3_alloc_rx_skb(struct tg3 *tp, u32 opaque_key,
map = &tp->rx_std_buffers[dest_idx];
if (src_idx >= 0)
src_map = &tp->rx_std_buffers[src_idx];
skb_size = tp->rx_pkt_buf_sz;
skb_size = tp->rx_pkt_map_sz;
break;
case RXD_OPAQUE_RING_JUMBO:
@ -4363,7 +4370,7 @@ static int tg3_alloc_rx_skb(struct tg3 *tp, u32 opaque_key,
map = &tp->rx_jumbo_buffers[dest_idx];
if (src_idx >= 0)
src_map = &tp->rx_jumbo_buffers[src_idx];
skb_size = RX_JUMBO_PKT_BUF_SZ;
skb_size = TG3_RX_JMB_MAP_SZ;
break;
default:
@ -4376,14 +4383,13 @@ static int tg3_alloc_rx_skb(struct tg3 *tp, u32 opaque_key,
* Callers depend upon this behavior and assume that
* we leave everything unchanged if we fail.
*/
skb = netdev_alloc_skb(tp->dev, skb_size);
skb = netdev_alloc_skb(tp->dev, skb_size + tp->rx_offset);
if (skb == NULL)
return -ENOMEM;
skb_reserve(skb, tp->rx_offset);
mapping = pci_map_single(tp->pdev, skb->data,
skb_size - tp->rx_offset,
mapping = pci_map_single(tp->pdev, skb->data, skb_size,
PCI_DMA_FROMDEVICE);
map->skb = skb;
@ -4540,8 +4546,7 @@ static int tg3_rx(struct tg3 *tp, int budget)
if (skb_size < 0)
goto drop_it;
pci_unmap_single(tp->pdev, dma_addr,
skb_size - tp->rx_offset,
pci_unmap_single(tp->pdev, dma_addr, skb_size,
PCI_DMA_FROMDEVICE);
skb_put(skb, len);
@ -5531,7 +5536,7 @@ static void tg3_free_rings(struct tg3 *tp)
continue;
pci_unmap_single(tp->pdev,
pci_unmap_addr(rxp, mapping),
tp->rx_pkt_buf_sz - tp->rx_offset,
tp->rx_pkt_map_sz,
PCI_DMA_FROMDEVICE);
dev_kfree_skb_any(rxp->skb);
rxp->skb = NULL;
@ -5544,7 +5549,7 @@ static void tg3_free_rings(struct tg3 *tp)
continue;
pci_unmap_single(tp->pdev,
pci_unmap_addr(rxp, mapping),
RX_JUMBO_PKT_BUF_SZ - tp->rx_offset,
TG3_RX_JMB_MAP_SZ,
PCI_DMA_FROMDEVICE);
dev_kfree_skb_any(rxp->skb);
rxp->skb = NULL;
@ -5581,7 +5586,7 @@ static void tg3_free_rings(struct tg3 *tp)
*/
static int tg3_init_rings(struct tg3 *tp)
{
u32 i;
u32 i, rx_pkt_dma_sz;
/* Free up all the SKBs. */
tg3_free_rings(tp);
@ -5592,10 +5597,11 @@ static int tg3_init_rings(struct tg3 *tp)
memset(tp->rx_rcb, 0, TG3_RX_RCB_RING_BYTES(tp));
memset(tp->tx_ring, 0, TG3_TX_RING_BYTES);
tp->rx_pkt_buf_sz = RX_PKT_BUF_SZ;
rx_pkt_dma_sz = TG3_RX_STD_DMA_SZ;
if ((tp->tg3_flags2 & TG3_FLG2_5780_CLASS) &&
(tp->dev->mtu > ETH_DATA_LEN))
tp->rx_pkt_buf_sz = RX_JUMBO_PKT_BUF_SZ;
tp->dev->mtu > ETH_DATA_LEN)
rx_pkt_dma_sz = TG3_RX_JMB_DMA_SZ;
tp->rx_pkt_map_sz = TG3_RX_DMA_TO_MAP_SZ(rx_pkt_dma_sz);
/* Initialize invariants of the rings, we only set this
* stuff once. This works because the card does not
@ -5605,8 +5611,7 @@ static int tg3_init_rings(struct tg3 *tp)
struct tg3_rx_buffer_desc *rxd;
rxd = &tp->rx_std[i];
rxd->idx_len = (tp->rx_pkt_buf_sz - tp->rx_offset - 64)
<< RXD_LEN_SHIFT;
rxd->idx_len = rx_pkt_dma_sz << RXD_LEN_SHIFT;
rxd->type_flags = (RXD_FLAG_END << RXD_FLAGS_SHIFT);
rxd->opaque = (RXD_OPAQUE_RING_STD |
(i << RXD_OPAQUE_INDEX_SHIFT));
@ -5617,8 +5622,7 @@ static int tg3_init_rings(struct tg3 *tp)
struct tg3_rx_buffer_desc *rxd;
rxd = &tp->rx_jumbo[i];
rxd->idx_len = (RX_JUMBO_PKT_BUF_SZ - tp->rx_offset - 64)
<< RXD_LEN_SHIFT;
rxd->idx_len = TG3_RX_JMB_DMA_SZ << RXD_LEN_SHIFT;
rxd->type_flags = (RXD_FLAG_END << RXD_FLAGS_SHIFT) |
RXD_FLAG_JUMBO;
rxd->opaque = (RXD_OPAQUE_RING_JUMBO |

2
drivers/net/tg3.h
View File

@ -2571,7 +2571,7 @@ struct tg3 {
struct tg3_rx_buffer_desc *rx_rcb;
dma_addr_t rx_rcb_mapping;
u32 rx_pkt_buf_sz;
u32 rx_pkt_map_sz;
/* begin "everything else" cacheline(s) section */
struct net_device_stats net_stats;