[dpdk-dev] [PATCH] net/fm10k: support Rx queue count API

[Xiao Wang <xiao.w.wang@intel.com>]

Some application, e.g. the l3fwd-power sample uses rte_eth_rx_queue_count()
API to get the get the number of used descriptors of a Rx queue. This patch
adds fm10k implementation for this API.

Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
---
 drivers/net/fm10k/fm10k.h        |  3 +++
 drivers/net/fm10k/fm10k_ethdev.c |  1 +
 drivers/net/fm10k/fm10k_rxtx.c   | 27 +++++++++++++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/drivers/net/fm10k/fm10k.h b/drivers/net/fm10k/fm10k.h
index dc814855d..b633b307b 100644
--- a/drivers/net/fm10k/fm10k.h
+++ b/drivers/net/fm10k/fm10k.h
@@ -323,6 +323,9 @@ uint16_t fm10k_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 uint16_t fm10k_recv_scattered_pkts(void *rx_queue,
 		struct rte_mbuf **rx_pkts, uint16_t nb_pkts);
 
+uint32_t
+fm10k_dev_rx_queue_count(struct rte_eth_dev *dev, uint16_t rx_queue_id);
+
 int
 fm10k_dev_rx_descriptor_done(void *rx_queue, uint16_t offset);
 
diff --git a/drivers/net/fm10k/fm10k_ethdev.c b/drivers/net/fm10k/fm10k_ethdev.c
index caf4d1bc0..47c20c5b2 100644
--- a/drivers/net/fm10k/fm10k_ethdev.c
+++ b/drivers/net/fm10k/fm10k_ethdev.c
@@ -2819,6 +2819,7 @@ static const struct eth_dev_ops fm10k_eth_dev_ops = {
 	.rx_queue_release	= fm10k_rx_queue_release,
 	.tx_queue_setup		= fm10k_tx_queue_setup,
 	.tx_queue_release	= fm10k_tx_queue_release,
+	.rx_queue_count		= fm10k_dev_rx_queue_count,
 	.rx_descriptor_done	= fm10k_dev_rx_descriptor_done,
 	.rx_descriptor_status = fm10k_dev_rx_descriptor_status,
 	.tx_descriptor_status = fm10k_dev_tx_descriptor_status,
diff --git a/drivers/net/fm10k/fm10k_rxtx.c b/drivers/net/fm10k/fm10k_rxtx.c
index fb02e1152..cc95f9589 100644
--- a/drivers/net/fm10k/fm10k_rxtx.c
+++ b/drivers/net/fm10k/fm10k_rxtx.c
@@ -366,6 +366,33 @@ fm10k_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 	return nb_rcv;
 }
 
+uint32_t
+fm10k_dev_rx_queue_count(struct rte_eth_dev *dev, uint16_t rx_queue_id)
+{
+#define FM10K_RXQ_SCAN_INTERVAL 4
+	volatile union fm10k_rx_desc *rxdp;
+	struct fm10k_rx_queue *rxq;
+	uint16_t desc = 0;
+
+	rxq = dev->data->rx_queues[rx_queue_id];
+	rxdp = &rxq->hw_ring[rxq->next_dd];
+	while ((desc < rxq->nb_desc) &&
+		rxdp->w.status & rte_cpu_to_le_16(FM10K_RXD_STATUS_DD)) {
+		/**
+		 * Check the DD bit of a rx descriptor of each group of 4 desc,
+		 * to avoid checking too frequently and downgrading performance
+		 * too much.
+		 */
+		desc += FM10K_RXQ_SCAN_INTERVAL;
+		rxdp += FM10K_RXQ_SCAN_INTERVAL;
+		if (rxq->next_dd + desc >= rxq->nb_desc)
+			rxdp = &rxq->hw_ring[rxq->next_dd + desc -
+				rxq->nb_desc];
+	}
+
+	return desc;
+}
+
 int
 fm10k_dev_rx_descriptor_done(void *rx_queue, uint16_t offset)
 {
-- 
2.15.1