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Date: Mon, 22 Apr 2019 09:46:44 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, Florian Fainelli <f.fainelli@...il.com>
Subject: [PATCH net-next] net: systemport: Remove need for DMA descriptor
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@...il.com>
---
drivers/net/ethernet/broadcom/bcmsysport.c | 56 +++-------------------
drivers/net/ethernet/broadcom/bcmsysport.h | 10 +---
2 files changed, 8 insertions(+), 58 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
index dfe46dacf5cf..4e87a303f83e 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -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;
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.h b/drivers/net/ethernet/broadcom/bcmsysport.h
index 0b192fea9c5d..6f3141c86436 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.h
+++ b/drivers/net/ethernet/broadcom/bcmsysport.h
@@ -516,12 +516,6 @@ struct bcm_rsb {
#define TDMA_DEBUG 0x64c
-/* Transmit/Receive descriptor */
-struct dma_desc {
- u32 addr_status_len;
- u32 addr_lo;
-};
-
/* Number of Receive hardware descriptor words */
#define SP_NUM_HW_RX_DESC_WORDS 1024
#define SP_LT_NUM_HW_RX_DESC_WORDS 256
@@ -530,7 +524,7 @@ struct dma_desc {
#define SP_NUM_TX_DESC 1536
#define SP_LT_NUM_TX_DESC 256
-#define WORDS_PER_DESC (sizeof(struct dma_desc) / sizeof(u32))
+#define WORDS_PER_DESC 2
/* Rx/Tx common counter group.*/
struct bcm_sysport_pkt_counters {
@@ -718,7 +712,6 @@ struct bcm_sysport_net_dim {
struct bcm_sysport_tx_ring {
spinlock_t lock; /* Ring lock for tx reclaim/xmit */
struct napi_struct napi; /* NAPI per tx queue */
- dma_addr_t desc_dma; /* DMA cookie */
unsigned int index; /* Ring index */
unsigned int size; /* Ring current size */
unsigned int alloc_size; /* Ring one-time allocated size */
@@ -727,7 +720,6 @@ struct bcm_sysport_tx_ring {
unsigned int c_index; /* Last consumer index */
unsigned int clean_index; /* Current clean index */
struct bcm_sysport_cb *cbs; /* Transmit control blocks */
- struct dma_desc *desc_cpu; /* CPU view of the descriptor */
struct bcm_sysport_priv *priv; /* private context backpointer */
unsigned long packets; /* packets statistics */
unsigned long bytes; /* bytes statistics */
--
2.17.1
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