From 287be12e1774d842bff21ea0c1809c2387d7b310 Mon Sep 17 00:00:00 2001 From: Matt Carlson Date: Fri, 28 Aug 2009 13:58:46 +0000 Subject: tg3: Clarify rx buffer relationships 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 Signed-off-by: David S. Miller --- drivers/net/tg3.c | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-) (limited to 'drivers/net/tg3.c') diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c index 5e74a19e7c12..a2a5f318315b 100644 --- a/drivers/net/tg3.c +++ b/drivers/net/tg3.c @@ -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 | -- cgit v1.2.3-59-g8ed1b