Function ixgbe_dev_tx_queue_setup

dpdk/drivers/net/ixgbe/ixgbe_rxtx.c:2615–2817

}

int __rte_cold
ixgbe_dev_tx_queue_setup(struct rte_eth_dev *dev,
			 uint16_t queue_idx,
			 uint16_t nb_desc,
			 unsigned int socket_id,
			 const struct rte_eth_txconf *tx_conf)
{
	const struct rte_memzone *tz;
	struct ixgbe_tx_queue *txq;
	struct ixgbe_hw     *hw;
	uint16_t tx_rs_thresh, tx_free_thresh;
	uint64_t offloads;

	PMD_INIT_FUNC_TRACE();
	hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);

	offloads = tx_conf->offloads | dev->data->dev_conf.txmode.offloads;

	/*
	 * Validate number of transmit descriptors.
	 * It must not exceed hardware maximum, and must be multiple
	 * of IXGBE_ALIGN.
	 */
	if (nb_desc % IXGBE_TXD_ALIGN != 0 ||
			(nb_desc > IXGBE_MAX_RING_DESC) ||
			(nb_desc < IXGBE_MIN_RING_DESC)) {
		return -EINVAL;
	}

	/*
	 * The following two parameters control the setting of the RS bit on
	 * transmit descriptors.
	 * TX descriptors will have their RS bit set after txq->tx_rs_thresh
	 * descriptors have been used.
	 * The TX descriptor ring will be cleaned after txq->tx_free_thresh
	 * descriptors are used or if the number of descriptors required
	 * to transmit a packet is greater than the number of free TX
	 * descriptors.
	 * The following constraints must be satisfied:
	 *  tx_rs_thresh must be greater than 0.
	 *  tx_rs_thresh must be less than the size of the ring minus 2.
	 *  tx_rs_thresh must be less than or equal to tx_free_thresh.
	 *  tx_rs_thresh must be a divisor of the ring size.
	 *  tx_free_thresh must be greater than 0.
	 *  tx_free_thresh must be less than the size of the ring minus 3.
	 *  tx_free_thresh + tx_rs_thresh must not exceed nb_desc.
	 * One descriptor in the TX ring is used as a sentinel to avoid a
	 * H/W race condition, hence the maximum threshold constraints.
	 * When set to zero use default values.
	 */
	tx_free_thresh = (uint16_t)((tx_conf->tx_free_thresh) ?
			tx_conf->tx_free_thresh : DEFAULT_TX_FREE_THRESH);
	/* force tx_rs_thresh to adapt an aggressive tx_free_thresh */
	tx_rs_thresh = (DEFAULT_TX_RS_THRESH + tx_free_thresh > nb_desc) ?
			nb_desc - tx_free_thresh : DEFAULT_TX_RS_THRESH;
	if (tx_conf->tx_rs_thresh > 0)
		tx_rs_thresh = tx_conf->tx_rs_thresh;
	if (tx_rs_thresh + tx_free_thresh > nb_desc) {