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Message-ID: <20141120170408.15397.42416.stgit@tlendack-t1.amdoffice.net>
Date: Thu, 20 Nov 2014 11:04:08 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: <netdev@...r.kernel.org>
CC: David Miller <davem@...emloft.net>
Subject: [PATCH net-next v1 8/8] amd-xgbe: Add support for the
skb->xmit_more flag
Add support to delay telling the hardware about data that is ready to
be transmitted if the skb->xmit_more flag is set.
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
drivers/net/ethernet/amd/xgbe/xgbe-desc.c | 5 +--
drivers/net/ethernet/amd/xgbe/xgbe-dev.c | 43 ++++++++++++++++++++---------
drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 37 +++++++++++++++++++++----
drivers/net/ethernet/amd/xgbe/xgbe.h | 15 ++++++++++
4 files changed, 78 insertions(+), 22 deletions(-)
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-desc.c b/drivers/net/ethernet/amd/xgbe/xgbe-desc.c
index 62cb4d3..51b68d1 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-desc.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-desc.c
@@ -378,7 +378,7 @@ static void xgbe_wrapper_tx_descriptor_init(struct xgbe_prv_data *pdata)
ring->cur = 0;
ring->dirty = 0;
- ring->tx.queue_stopped = 0;
+ memset(&ring->tx, 0, sizeof(ring->tx));
hw_if->tx_desc_init(channel);
}
@@ -422,8 +422,7 @@ static void xgbe_wrapper_rx_descriptor_init(struct xgbe_prv_data *pdata)
ring->cur = 0;
ring->dirty = 0;
- ring->rx.realloc_index = 0;
- ring->rx.realloc_threshold = 0;
+ memset(&ring->rx, 0, sizeof(ring->rx));
hw_if->rx_desc_init(channel);
}
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index b3d2433..53f5f66 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -1325,6 +1325,29 @@ static void xgbe_config_dcb_pfc(struct xgbe_prv_data *pdata)
xgbe_config_flow_control(pdata);
}
+static void xgbe_tx_start_xmit(struct xgbe_channel *channel,
+ struct xgbe_ring *ring)
+{
+ struct xgbe_prv_data *pdata = channel->pdata;
+ struct xgbe_ring_data *rdata;
+
+ /* Issue a poll command to Tx DMA by writing address
+ * of next immediate free descriptor */
+ rdata = XGBE_GET_DESC_DATA(ring, ring->cur);
+ XGMAC_DMA_IOWRITE(channel, DMA_CH_TDTR_LO,
+ lower_32_bits(rdata->rdesc_dma));
+
+ /* Start the Tx coalescing timer */
+ if (pdata->tx_usecs && !channel->tx_timer_active) {
+ channel->tx_timer_active = 1;
+ hrtimer_start(&channel->tx_timer,
+ ktime_set(0, pdata->tx_usecs * NSEC_PER_USEC),
+ HRTIMER_MODE_REL);
+ }
+
+ ring->tx.xmit_more = 0;
+}
+
static void xgbe_dev_xmit(struct xgbe_channel *channel)
{
struct xgbe_prv_data *pdata = channel->pdata;
@@ -1528,20 +1551,13 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
/* Make sure ownership is written to the descriptor */
wmb();
- /* Issue a poll command to Tx DMA by writing address
- * of next immediate free descriptor */
ring->cur++;
- rdata = XGBE_GET_DESC_DATA(ring, ring->cur);
- XGMAC_DMA_IOWRITE(channel, DMA_CH_TDTR_LO,
- lower_32_bits(rdata->rdesc_dma));
-
- /* Start the Tx coalescing timer */
- if (pdata->tx_usecs && !channel->tx_timer_active) {
- channel->tx_timer_active = 1;
- hrtimer_start(&channel->tx_timer,
- ktime_set(0, pdata->tx_usecs * NSEC_PER_USEC),
- HRTIMER_MODE_REL);
- }
+ if (!packet->skb->xmit_more ||
+ netif_xmit_stopped(netdev_get_tx_queue(pdata->netdev,
+ channel->queue_index)))
+ xgbe_tx_start_xmit(channel, ring);
+ else
+ ring->tx.xmit_more = 1;
DBGPR(" %s: descriptors %u to %u written\n",
channel->name, start_index & (ring->rdesc_count - 1),
@@ -2802,6 +2818,7 @@ void xgbe_init_function_ptrs_dev(struct xgbe_hw_if *hw_if)
hw_if->rx_desc_reset = xgbe_rx_desc_reset;
hw_if->is_last_desc = xgbe_is_last_desc;
hw_if->is_context_desc = xgbe_is_context_desc;
+ hw_if->tx_start_xmit = xgbe_tx_start_xmit;
/* For FLOW ctrl */
hw_if->config_tx_flow_control = xgbe_config_tx_flow_control;
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index f963528..02c104d 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -225,6 +225,28 @@ static inline unsigned int xgbe_tx_avail_desc(struct xgbe_ring *ring)
return (ring->rdesc_count - (ring->cur - ring->dirty));
}
+static int xgbe_maybe_stop_tx_queue(struct xgbe_channel *channel,
+ struct xgbe_ring *ring, unsigned int count)
+{
+ struct xgbe_prv_data *pdata = channel->pdata;
+
+ if (count > xgbe_tx_avail_desc(ring)) {
+ DBGPR(" Tx queue stopped, not enough descriptors available\n");
+ netif_stop_subqueue(pdata->netdev, channel->queue_index);
+ ring->tx.queue_stopped = 1;
+
+ /* If we haven't notified the hardware because of xmit_more
+ * support, tell it now
+ */
+ if (ring->tx.xmit_more)
+ pdata->hw_if.tx_start_xmit(channel, ring);
+
+ return NETDEV_TX_BUSY;
+ }
+
+ return 0;
+}
+
static int xgbe_calc_rx_buf_size(struct net_device *netdev, unsigned int mtu)
{
unsigned int rx_buf_size;
@@ -1199,6 +1221,8 @@ static void xgbe_packet_info(struct xgbe_prv_data *pdata,
unsigned int len;
unsigned int i;
+ packet->skb = skb;
+
context_desc = 0;
packet->rdesc_count = 0;
@@ -1447,13 +1471,9 @@ static int xgbe_xmit(struct sk_buff *skb, struct net_device *netdev)
xgbe_packet_info(pdata, ring, skb, packet);
/* Check that there are enough descriptors available */
- if (packet->rdesc_count > xgbe_tx_avail_desc(ring)) {
- DBGPR(" Tx queue stopped, not enough descriptors available\n");
- netif_stop_subqueue(netdev, channel->queue_index);
- ring->tx.queue_stopped = 1;
- ret = NETDEV_TX_BUSY;
+ ret = xgbe_maybe_stop_tx_queue(channel, ring, packet->rdesc_count);
+ if (ret)
goto tx_netdev_return;
- }
ret = xgbe_prep_tso(skb, packet);
if (ret) {
@@ -1480,6 +1500,11 @@ static int xgbe_xmit(struct sk_buff *skb, struct net_device *netdev)
xgbe_print_pkt(netdev, skb, true);
#endif
+ /* Stop the queue in advance if there may not be enough descriptors */
+ xgbe_maybe_stop_tx_queue(channel, ring, XGBE_TX_MAX_DESCS);
+
+ ret = NETDEV_TX_OK;
+
tx_netdev_return:
spin_unlock_irqrestore(&ring->lock, flags);
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe.h b/drivers/net/ethernet/amd/xgbe/xgbe.h
index ec0d37a..eb33873 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe.h
+++ b/drivers/net/ethernet/amd/xgbe/xgbe.h
@@ -140,6 +140,17 @@
#define XGBE_TX_MAX_BUF_SIZE (0x3fff & ~(64 - 1))
+/* Descriptors required for maximum contigous TSO/GSO packet */
+#define XGBE_TX_MAX_SPLIT ((GSO_MAX_SIZE / XGBE_TX_MAX_BUF_SIZE) + 1)
+
+/* Maximum possible descriptors needed for an SKB:
+ * - Maximum number of SKB frags
+ * - Maximum descriptors for contiguous TSO/GSO packet
+ * - Possible context descriptor
+ * - Possible TSO header descriptor
+ */
+#define XGBE_TX_MAX_DESCS (MAX_SKB_FRAGS + XGBE_TX_MAX_SPLIT + 2)
+
#define XGBE_RX_MIN_BUF_SIZE (ETH_FRAME_LEN + ETH_FCS_LEN + VLAN_HLEN)
#define XGBE_RX_BUF_ALIGN 64
#define XGBE_SKB_ALLOC_SIZE 256
@@ -225,6 +236,8 @@
struct xgbe_prv_data;
struct xgbe_packet_data {
+ struct sk_buff *skb;
+
unsigned int attributes;
unsigned int errors;
@@ -360,6 +373,7 @@ struct xgbe_ring {
union {
struct {
unsigned int queue_stopped;
+ unsigned int xmit_more;
unsigned short cur_mss;
unsigned short cur_vlan_ctag;
} tx;
@@ -523,6 +537,7 @@ struct xgbe_hw_if {
void (*tx_desc_reset)(struct xgbe_ring_data *);
int (*is_last_desc)(struct xgbe_ring_desc *);
int (*is_context_desc)(struct xgbe_ring_desc *);
+ void (*tx_start_xmit)(struct xgbe_channel *, struct xgbe_ring *);
/* For FLOW ctrl */
int (*config_tx_flow_control)(struct xgbe_prv_data *);
--
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