Driver Design¶

QDMA DPDK driver is implemented as an Ethernet poll mode driver in DPDK v20.11. It supports both streaming (network) and memory (compute) interface to QDMA. Below diagram gives a high level system overview of the QDMA DPDK driver.

Below sections describes design of different blocks and use cases of DPDK driver.

Driver interfaces and callbacks¶

The Driver registers two driver interfaces (net_qdma for PFs and net_qdma_vf for VFs) with DPDK RTE. Below eth_dev_ops callbacks are implemented by both driver interfaces of the DPDK driver.

static struct eth_dev_ops qdma_eth_dev_ops = {
        .dev_configure            = qdma_dev_configure,
        .dev_infos_get            = qdma_dev_infos_get,
        .dev_start                = qdma_dev_start,
        .dev_stop                 = qdma_dev_stop,
        .dev_close                = qdma_dev_close,
        .dev_reset                = qdma_dev_reset,
        .link_update              = qdma_dev_link_update,
        .rx_queue_setup           = qdma_dev_rx_queue_setup,
        .tx_queue_setup           = qdma_dev_tx_queue_setup,
        .rx_queue_release         = qdma_dev_rx_queue_release,
        .tx_queue_release         = qdma_dev_tx_queue_release,
        .rx_queue_start           = qdma_dev_rx_queue_start,
        .rx_queue_stop            = qdma_dev_rx_queue_stop,
        .tx_queue_start           = qdma_dev_tx_queue_start,
        .tx_queue_stop            = qdma_dev_tx_queue_stop,
        .rx_queue_count           = qdma_dev_rx_queue_count,
        .rx_descriptor_status     = qdma_dev_rx_descriptor_status,
        .tx_descriptor_status     = qdma_dev_tx_descriptor_status,
        .tx_done_cleanup          = qdma_dev_tx_done_cleanup,
        .queue_stats_mapping_set  = qdma_dev_queue_stats_mapping,
        .get_reg                  = qdma_dev_get_regs,
        .stats_get                = qdma_dev_stats_get,
        .stats_reset              = qdma_dev_stats_reset,
        .rxq_info_get             = qdma_dev_rxq_info_get,
        .txq_info_get             = qdma_dev_txq_info_get,
};

Below sequence diagram depicts the application call flow to these driver callbacks and their high level operations.

Implementation details of the callback APIs is described further in

DPDK Callback APIs

Additional interfaces are exported by the driver for QDMA configuration. These new interfaces are described in

QDMA DPDK PMD Exported APIs

Resource Management¶

QDMA Queue Resource Management

Mailbox Communication for VF configuration¶

QDMA Mailbox

PF/VF Shutdown¶

PF/VF Shutdown

DPDK Driver Interop with Linux Driver¶

DPDK Driver Interop with Linux Driver

QDMA Hardware Error Monitoring¶

There are various causes for errors in QDMA IP e.g. descriptor errors, DMA engine errors, etc. If the errors are enabled by SW, QDMA logs the status of error in the respective global status registers.

DPDK driver executes a poll thread qdma_check_errors() every 1 second to check the error status and log the type of HW error occured on the console.

DPDK Driver debug¶

DPDK driver provides below APIs to dump debug information.

rte_pmd_qdma_dbg_regdump(): Dump QDMA registers
rte_pmd_qdma_dbg_qdevice(): Dump QDMA device structure maintained by SW
rte_pmd_qdma_dbg_qinfo(): Dump QDMA queue context maintained by HW and queue structures maintained by SW
rte_pmd_qdma_dbg_qdesc(): Dump the specified descriptor ring of the given queue id

User application can call these APIs to dump the required debug information.