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author | Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> | 2015-07-25 23:42:01 +0300 |
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committer | David S. Miller <davem@davemloft.net> | 2015-07-27 01:22:38 -0700 |
commit | 2f45d1902acfc7e6680cfeeb38922dcc7e16deb6 (patch) | |
tree | 5d65107c25abf0912aacc61ea3ecb97796a2f464 /drivers/net/ethernet/renesas/ravb_main.c | |
parent | c22995c5488d7048554d85ee5ee8a269932b0aea (diff) | |
download | op-kernel-dev-2f45d1902acfc7e6680cfeeb38922dcc7e16deb6.zip op-kernel-dev-2f45d1902acfc7e6680cfeeb38922dcc7e16deb6.tar.gz |
ravb: minimize TX data copying
Renesas Ethernet AVB controller requires that all data are aligned on 4-byte
boundary. While it's easily achievable for the RX data with the help of
skb_reserve() (we even align on 128-byte boundary as recommended by the manual),
we can't do the same with the TX data, and it always comes unaligned from
the networking core. Originally we solved it an easy way, copying all packet
to a preallocated aligned buffer; however, it's enough to copy only up to
3 first bytes from each packet, doing the transfer using 2 TX descriptors
instead of just 1. Here's an implementation of the new TX algorithm that
significantly reduces the driver's memory requirements.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/renesas/ravb_main.c')
-rw-r--r-- | drivers/net/ethernet/renesas/ravb_main.c | 104 |
1 files changed, 60 insertions, 44 deletions
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c index 779bb58..3d972d8 100644 --- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -195,12 +195,8 @@ static void ravb_ring_free(struct net_device *ndev, int q) priv->tx_skb[q] = NULL; /* Free aligned TX buffers */ - if (priv->tx_buffers[q]) { - for (i = 0; i < priv->num_tx_ring[q]; i++) - kfree(priv->tx_buffers[q][i]); - } - kfree(priv->tx_buffers[q]); - priv->tx_buffers[q] = NULL; + kfree(priv->tx_align[q]); + priv->tx_align[q] = NULL; if (priv->rx_ring[q]) { ring_size = sizeof(struct ravb_ex_rx_desc) * @@ -212,7 +208,7 @@ static void ravb_ring_free(struct net_device *ndev, int q) if (priv->tx_ring[q]) { ring_size = sizeof(struct ravb_tx_desc) * - (priv->num_tx_ring[q] + 1); + (priv->num_tx_ring[q] * NUM_TX_DESC + 1); dma_free_coherent(NULL, ring_size, priv->tx_ring[q], priv->tx_desc_dma[q]); priv->tx_ring[q] = NULL; @@ -227,7 +223,8 @@ static void ravb_ring_format(struct net_device *ndev, int q) struct ravb_tx_desc *tx_desc; struct ravb_desc *desc; int rx_ring_size = sizeof(*rx_desc) * priv->num_rx_ring[q]; - int tx_ring_size = sizeof(*tx_desc) * priv->num_tx_ring[q]; + int tx_ring_size = sizeof(*tx_desc) * priv->num_tx_ring[q] * + NUM_TX_DESC; dma_addr_t dma_addr; int i; @@ -260,11 +257,12 @@ static void ravb_ring_format(struct net_device *ndev, int q) memset(priv->tx_ring[q], 0, tx_ring_size); /* Build TX ring buffer */ - for (i = 0; i < priv->num_tx_ring[q]; i++) { - tx_desc = &priv->tx_ring[q][i]; + for (i = 0, tx_desc = priv->tx_ring[q]; i < priv->num_tx_ring[q]; + i++, tx_desc++) { + tx_desc->die_dt = DT_EEMPTY; + tx_desc++; tx_desc->die_dt = DT_EEMPTY; } - tx_desc = &priv->tx_ring[q][i]; tx_desc->dptr = cpu_to_le32((u32)priv->tx_desc_dma[q]); tx_desc->die_dt = DT_LINKFIX; /* type */ @@ -285,7 +283,6 @@ static int ravb_ring_init(struct net_device *ndev, int q) struct ravb_private *priv = netdev_priv(ndev); struct sk_buff *skb; int ring_size; - void *buffer; int i; /* Allocate RX and TX skb rings */ @@ -305,19 +302,11 @@ static int ravb_ring_init(struct net_device *ndev, int q) } /* Allocate rings for the aligned buffers */ - priv->tx_buffers[q] = kcalloc(priv->num_tx_ring[q], - sizeof(*priv->tx_buffers[q]), GFP_KERNEL); - if (!priv->tx_buffers[q]) + priv->tx_align[q] = kmalloc(DPTR_ALIGN * priv->num_tx_ring[q] + + DPTR_ALIGN - 1, GFP_KERNEL); + if (!priv->tx_align[q]) goto error; - for (i = 0; i < priv->num_tx_ring[q]; i++) { - buffer = kmalloc(PKT_BUF_SZ + RAVB_ALIGN - 1, GFP_KERNEL); - if (!buffer) - goto error; - /* Aligned TX buffer */ - priv->tx_buffers[q][i] = buffer; - } - /* Allocate all RX descriptors. */ ring_size = sizeof(struct ravb_ex_rx_desc) * (priv->num_rx_ring[q] + 1); priv->rx_ring[q] = dma_alloc_coherent(NULL, ring_size, @@ -329,7 +318,8 @@ static int ravb_ring_init(struct net_device *ndev, int q) priv->dirty_rx[q] = 0; /* Allocate all TX descriptors. */ - ring_size = sizeof(struct ravb_tx_desc) * (priv->num_tx_ring[q] + 1); + ring_size = sizeof(struct ravb_tx_desc) * + (priv->num_tx_ring[q] * NUM_TX_DESC + 1); priv->tx_ring[q] = dma_alloc_coherent(NULL, ring_size, &priv->tx_desc_dma[q], GFP_KERNEL); @@ -443,7 +433,8 @@ static int ravb_tx_free(struct net_device *ndev, int q) u32 size; for (; priv->cur_tx[q] - priv->dirty_tx[q] > 0; priv->dirty_tx[q]++) { - entry = priv->dirty_tx[q] % priv->num_tx_ring[q]; + entry = priv->dirty_tx[q] % (priv->num_tx_ring[q] * + NUM_TX_DESC); desc = &priv->tx_ring[q][entry]; if (desc->die_dt != DT_FEMPTY) break; @@ -451,14 +442,18 @@ static int ravb_tx_free(struct net_device *ndev, int q) dma_rmb(); size = le16_to_cpu(desc->ds_tagl) & TX_DS; /* Free the original skb. */ - if (priv->tx_skb[q][entry]) { + if (priv->tx_skb[q][entry / NUM_TX_DESC]) { dma_unmap_single(&ndev->dev, le32_to_cpu(desc->dptr), size, DMA_TO_DEVICE); - dev_kfree_skb_any(priv->tx_skb[q][entry]); - priv->tx_skb[q][entry] = NULL; + /* Last packet descriptor? */ + if (entry % NUM_TX_DESC == NUM_TX_DESC - 1) { + entry /= NUM_TX_DESC; + dev_kfree_skb_any(priv->tx_skb[q][entry]); + priv->tx_skb[q][entry] = NULL; + stats->tx_packets++; + } free_num++; } - stats->tx_packets++; stats->tx_bytes += size; desc->die_dt = DT_EEMPTY; } @@ -1284,37 +1279,53 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev) u32 dma_addr; void *buffer; u32 entry; + u32 len; spin_lock_irqsave(&priv->lock, flags); - if (priv->cur_tx[q] - priv->dirty_tx[q] >= priv->num_tx_ring[q]) { + if (priv->cur_tx[q] - priv->dirty_tx[q] > (priv->num_tx_ring[q] - 1) * + NUM_TX_DESC) { netif_err(priv, tx_queued, ndev, "still transmitting with the full ring!\n"); netif_stop_subqueue(ndev, q); spin_unlock_irqrestore(&priv->lock, flags); return NETDEV_TX_BUSY; } - entry = priv->cur_tx[q] % priv->num_tx_ring[q]; - priv->tx_skb[q][entry] = skb; + entry = priv->cur_tx[q] % (priv->num_tx_ring[q] * NUM_TX_DESC); + priv->tx_skb[q][entry / NUM_TX_DESC] = skb; if (skb_put_padto(skb, ETH_ZLEN)) goto drop; - buffer = PTR_ALIGN(priv->tx_buffers[q][entry], RAVB_ALIGN); - memcpy(buffer, skb->data, skb->len); - desc = &priv->tx_ring[q][entry]; - desc->ds_tagl = cpu_to_le16(skb->len); - dma_addr = dma_map_single(&ndev->dev, buffer, skb->len, DMA_TO_DEVICE); + buffer = PTR_ALIGN(priv->tx_align[q], DPTR_ALIGN) + + entry / NUM_TX_DESC * DPTR_ALIGN; + len = PTR_ALIGN(skb->data, DPTR_ALIGN) - skb->data; + memcpy(buffer, skb->data, len); + dma_addr = dma_map_single(&ndev->dev, buffer, len, DMA_TO_DEVICE); if (dma_mapping_error(&ndev->dev, dma_addr)) goto drop; + + desc = &priv->tx_ring[q][entry]; + desc->ds_tagl = cpu_to_le16(len); + desc->dptr = cpu_to_le32(dma_addr); + + buffer = skb->data + len; + len = skb->len - len; + dma_addr = dma_map_single(&ndev->dev, buffer, len, DMA_TO_DEVICE); + if (dma_mapping_error(&ndev->dev, dma_addr)) + goto unmap; + + desc++; + desc->ds_tagl = cpu_to_le16(len); desc->dptr = cpu_to_le32(dma_addr); /* TX timestamp required */ if (q == RAVB_NC) { ts_skb = kmalloc(sizeof(*ts_skb), GFP_ATOMIC); if (!ts_skb) { - dma_unmap_single(&ndev->dev, dma_addr, skb->len, + desc--; + dma_unmap_single(&ndev->dev, dma_addr, len, DMA_TO_DEVICE); - goto drop; + goto unmap; } ts_skb->skb = skb; ts_skb->tag = priv->ts_skb_tag++; @@ -1330,13 +1341,15 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev) /* Descriptor type must be set after all the above writes */ dma_wmb(); - desc->die_dt = DT_FSINGLE; + desc->die_dt = DT_FEND; + desc--; + desc->die_dt = DT_FSTART; ravb_write(ndev, ravb_read(ndev, TCCR) | (TCCR_TSRQ0 << q), TCCR); - priv->cur_tx[q]++; - if (priv->cur_tx[q] - priv->dirty_tx[q] >= priv->num_tx_ring[q] && - !ravb_tx_free(ndev, q)) + priv->cur_tx[q] += NUM_TX_DESC; + if (priv->cur_tx[q] - priv->dirty_tx[q] > + (priv->num_tx_ring[q] - 1) * NUM_TX_DESC && !ravb_tx_free(ndev, q)) netif_stop_subqueue(ndev, q); exit: @@ -1344,9 +1357,12 @@ exit: spin_unlock_irqrestore(&priv->lock, flags); return NETDEV_TX_OK; +unmap: + dma_unmap_single(&ndev->dev, le32_to_cpu(desc->dptr), + le16_to_cpu(desc->ds_tagl), DMA_TO_DEVICE); drop: dev_kfree_skb_any(skb); - priv->tx_skb[q][entry] = NULL; + priv->tx_skb[q][entry / NUM_TX_DESC] = NULL; goto exit; } |