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net: systemport: Remove need for DMA descriptor

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All we do is write the length/status and address bits to a DMA
descriptor only to write its contents into on-chip registers right
after, eliminate this unnecessary step.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Fainelli
2019-04-22 09:46:44 -07:00
committed by David S. Miller
parent 697cd36cda
commit 7e6e185c74
2 changed files with 8 additions and 58 deletions
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56
drivers/net/ethernet/broadcom/bcmsysport.c
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@@ -116,15 +116,6 @@ static inline void dma_desc_set_addr(struct bcm_sysport_priv *priv,
writel_relaxed(lower_32_bits(addr), d + DESC_ADDR_LO);
}
static inline void tdma_port_write_desc_addr(struct bcm_sysport_priv *priv,
struct dma_desc *desc,
unsigned int port)
{
/* Ports are latched, so write upper address first */
tdma_writel(priv, desc->addr_status_len, TDMA_WRITE_PORT_HI(port));
tdma_writel(priv, desc->addr_lo, TDMA_WRITE_PORT_LO(port));
}
/* Ethtool operations */
static void bcm_sysport_set_rx_csum(struct net_device *dev,
netdev_features_t wanted)
@@ -1291,11 +1282,10 @@ static netdev_tx_t bcm_sysport_xmit(struct sk_buff *skb,
struct bcm_sysport_tx_ring *ring;
struct bcm_sysport_cb *cb;
struct netdev_queue *txq;
struct dma_desc *desc;
u32 len_status, addr_lo;
unsigned int skb_len;
unsigned long flags;
dma_addr_t mapping;
u32 len_status;
u16 queue;
int ret;
@@ -1338,10 +1328,7 @@ static netdev_tx_t bcm_sysport_xmit(struct sk_buff *skb,
dma_unmap_addr_set(cb, dma_addr, mapping);
dma_unmap_len_set(cb, dma_len, skb_len);
/* Fetch a descriptor entry from our pool */
desc = ring->desc_cpu;
desc->addr_lo = lower_32_bits(mapping);
addr_lo = lower_32_bits(mapping);
len_status = upper_32_bits(mapping) & DESC_ADDR_HI_MASK;
len_status |= (skb_len << DESC_LEN_SHIFT);
len_status |= (DESC_SOP | DESC_EOP | TX_STATUS_APP_CRC) <<
@@ -1354,16 +1341,9 @@ static netdev_tx_t bcm_sysport_xmit(struct sk_buff *skb,
ring->curr_desc = 0;
ring->desc_count--;
/* Ensure write completion of the descriptor status/length
* in DRAM before the System Port WRITE_PORT register latches
* the value
*/
wmb();
desc->addr_status_len = len_status;
wmb();
/* Write this descriptor address to the RING write port */
tdma_port_write_desc_addr(priv, desc, ring->index);
/* Ports are latched, so write upper address first */
tdma_writel(priv, len_status, TDMA_WRITE_PORT_HI(ring->index));
tdma_writel(priv, addr_lo, TDMA_WRITE_PORT_LO(ring->index));
/* Check ring space and update SW control flow */
if (ring->desc_count == 0)
@@ -1489,28 +1469,14 @@ static int bcm_sysport_init_tx_ring(struct bcm_sysport_priv *priv,
unsigned int index)
{
struct bcm_sysport_tx_ring *ring = &priv->tx_rings[index];
struct device *kdev = &priv->pdev->dev;
size_t size;
void *p;
u32 reg;
/* Simple descriptors partitioning for now */
size = 256;
/* We just need one DMA descriptor which is DMA-able, since writing to
* the port will allocate a new descriptor in its internal linked-list
*/
p = dma_alloc_coherent(kdev, sizeof(struct dma_desc), &ring->desc_dma,
GFP_KERNEL);
if (!p) {
netif_err(priv, hw, priv->netdev, "DMA alloc failed\n");
return -ENOMEM;
}
ring->cbs = kcalloc(size, sizeof(struct bcm_sysport_cb), GFP_KERNEL);
if (!ring->cbs) {
dma_free_coherent(kdev, sizeof(struct dma_desc),
ring->desc_cpu, ring->desc_dma);
netif_err(priv, hw, priv->netdev, "CB allocation failed\n");
return -ENOMEM;
}
@@ -1523,7 +1489,6 @@ static int bcm_sysport_init_tx_ring(struct bcm_sysport_priv *priv,
ring->size = size;
ring->clean_index = 0;
ring->alloc_size = ring->size;
ring->desc_cpu = p;
ring->desc_count = ring->size;
ring->curr_desc = 0;
@@ -1578,8 +1543,8 @@ static int bcm_sysport_init_tx_ring(struct bcm_sysport_priv *priv,
napi_enable(&ring->napi);
netif_dbg(priv, hw, priv->netdev,
"TDMA cfg, size=%d, desc_cpu=%p switch q=%d,port=%d\n",
ring->size, ring->desc_cpu, ring->switch_queue,
"TDMA cfg, size=%d, switch q=%d,port=%d\n",
ring->size, ring->switch_queue,
ring->switch_port);
return 0;
@@ -1589,7 +1554,6 @@ static void bcm_sysport_fini_tx_ring(struct bcm_sysport_priv *priv,
unsigned int index)
{
struct bcm_sysport_tx_ring *ring = &priv->tx_rings[index];
struct device *kdev = &priv->pdev->dev;
u32 reg;
/* Caller should stop the TDMA engine */
@@ -1611,12 +1575,6 @@ static void bcm_sysport_fini_tx_ring(struct bcm_sysport_priv *priv,
kfree(ring->cbs);
ring->cbs = NULL;
if (ring->desc_dma) {
dma_free_coherent(kdev, sizeof(struct dma_desc),
ring->desc_cpu, ring->desc_dma);
ring->desc_dma = 0;
}
ring->size = 0;
ring->alloc_size = 0;