[PATCH net-next v2 3/6] net: stmmac: arrange Tx tail pointer update to stmmac_flush_tx_descriptors

From: Ong Boon Leong
Date: Mon Mar 29 2021 - 22:46:49 EST


This patch organizes TX tail pointer update into a new function called
stmmac_flush_tx_descriptors() so that we can reuse it in stmmac_xmit(),
stmmac_tso_xmit() and up-coming XDP implementation.

Changes to v2:
- Fix for warning: unused variable ‘desc_size’
https://patchwork.hopto.org/static/nipa/457321/12170149/build_32bit/stderr

Signed-off-by: Ong Boon Leong <boon.leong.ong@xxxxxxxxx>
---
.../net/ethernet/stmicro/stmmac/stmmac_main.c | 56 +++++++++----------
1 file changed, 26 insertions(+), 30 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 18e34a1e2367..cb1b2a180429 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3518,6 +3518,28 @@ static void stmmac_tso_allocator(struct stmmac_priv *priv, dma_addr_t des,
}
}

+static void stmmac_flush_tx_descriptors(struct stmmac_priv *priv, int queue)
+{
+ struct stmmac_tx_queue *tx_q = &priv->tx_queue[queue];
+ int desc_size;
+
+ if (likely(priv->extend_desc))
+ desc_size = sizeof(struct dma_extended_desc);
+ else if (tx_q->tbs & STMMAC_TBS_AVAIL)
+ desc_size = sizeof(struct dma_edesc);
+ else
+ desc_size = sizeof(struct dma_desc);
+
+ /* The own bit must be the latest setting done when prepare the
+ * descriptor and then barrier is needed to make sure that
+ * all is coherent before granting the DMA engine.
+ */
+ wmb();
+
+ tx_q->tx_tail_addr = tx_q->dma_tx_phy + (tx_q->cur_tx * desc_size);
+ stmmac_set_tx_tail_ptr(priv, priv->ioaddr, tx_q->tx_tail_addr, queue);
+}
+
/**
* stmmac_tso_xmit - Tx entry point of the driver for oversized frames (TSO)
* @skb : the socket buffer
@@ -3549,10 +3571,10 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dma_desc *desc, *first, *mss_desc = NULL;
struct stmmac_priv *priv = netdev_priv(dev);
- int desc_size, tmp_pay_len = 0, first_tx;
int nfrags = skb_shinfo(skb)->nr_frags;
u32 queue = skb_get_queue_mapping(skb);
unsigned int first_entry, tx_packets;
+ int tmp_pay_len = 0, first_tx;
struct stmmac_tx_queue *tx_q;
bool has_vlan, set_ic;
u8 proto_hdr_len, hdr;
@@ -3750,12 +3772,6 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)
stmmac_set_tx_owner(priv, mss_desc);
}

- /* The own bit must be the latest setting done when prepare the
- * descriptor and then barrier is needed to make sure that
- * all is coherent before granting the DMA engine.
- */
- wmb();
-
if (netif_msg_pktdata(priv)) {
pr_info("%s: curr=%d dirty=%d f=%d, e=%d, f_p=%p, nfrags %d\n",
__func__, tx_q->cur_tx, tx_q->dirty_tx, first_entry,
@@ -3766,13 +3782,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev)

netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len);

- if (tx_q->tbs & STMMAC_TBS_AVAIL)
- desc_size = sizeof(struct dma_edesc);
- else
- desc_size = sizeof(struct dma_desc);
-
- tx_q->tx_tail_addr = tx_q->dma_tx_phy + (tx_q->cur_tx * desc_size);
- stmmac_set_tx_tail_ptr(priv, priv->ioaddr, tx_q->tx_tail_addr, queue);
+ stmmac_flush_tx_descriptors(priv, queue);
stmmac_tx_timer_arm(priv, queue);

return NETDEV_TX_OK;
@@ -3802,10 +3812,10 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
int nfrags = skb_shinfo(skb)->nr_frags;
int gso = skb_shinfo(skb)->gso_type;
struct dma_edesc *tbs_desc = NULL;
- int entry, desc_size, first_tx;
struct dma_desc *desc, *first;
struct stmmac_tx_queue *tx_q;
bool has_vlan, set_ic;
+ int entry, first_tx;
dma_addr_t des;

tx_q = &priv->tx_queue[queue];
@@ -4007,25 +4017,11 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)

stmmac_set_tx_owner(priv, first);

- /* The own bit must be the latest setting done when prepare the
- * descriptor and then barrier is needed to make sure that
- * all is coherent before granting the DMA engine.
- */
- wmb();
-
netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len);

stmmac_enable_dma_transmission(priv, priv->ioaddr);

- if (likely(priv->extend_desc))
- desc_size = sizeof(struct dma_extended_desc);
- else if (tx_q->tbs & STMMAC_TBS_AVAIL)
- desc_size = sizeof(struct dma_edesc);
- else
- desc_size = sizeof(struct dma_desc);
-
- tx_q->tx_tail_addr = tx_q->dma_tx_phy + (tx_q->cur_tx * desc_size);
- stmmac_set_tx_tail_ptr(priv, priv->ioaddr, tx_q->tx_tail_addr, queue);
+ stmmac_flush_tx_descriptors(priv, queue);
stmmac_tx_timer_arm(priv, queue);

return NETDEV_TX_OK;
--
2.25.1