Re: [PATCH v3 0/6] net/dpaa2: NAPI-style Rx queue interrupts

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 30 Jun 2026 16:43:23 +0200
Maxime Leroy <maxime@leroys.fr> wrote:

> This series lets a dpaa2 worker sleep on a queue's data-availability
> notification instead of busy-polling, exposed through the generic
> rte_eth_dev_rx_intr_* API (NAPI-style: poll while frames keep coming,
> arm the interrupt and sleep when the queue runs dry).
> 
> Why it is not a trivial .rx_queue_intr_enable
> ----------------------------------------------
> A worker wakes on its software portal's DQRI, which fires when the
> portal's DQRR holds frames. The default dpaa2 Rx burst pulls frames
> from the FQ with a volatile dequeue and cannot be interrupt-driven; to
> wake on the DQRI the FQ must instead be pushed to the portal's DQRR.
> 
> The natural dpni_set_queue with a notification destination would have to
> target the worker's portal, but that portal is only known once a worker
> affines, after dev_start, and that MC command holds the global MC lock
> long enough to wedge the firmware while traffic runs. So the bind cannot
> be done late, against the polling lcore.
> 
> Design
> ------
> Each Rx FQ is bound to its own DPCON channel, statically, at dev_start
> while the dpni is still disabled (no knowledge of the polling lcore). A
> worker later subscribes its own ethrx portal to the channel and arms the
> DQRI in rx_queue_intr_enable, a one-shot per-portal op, never the wedging
> set_queue. On a wakeup the worker drains each of its queues by a volatile
> dequeue on the queue's own DPCON channel (one FQ per channel, so no
> per-frame demux); it polls all its queues, the same scheduling contract
> as plain DPDK polling. A queue can be re-homed to another lcore at
> runtime with no set_queue and no port stop.
> 
> This reuses the event PMD's pushed/DQRR model but with one DPCON per FQ
> and static affinity (no QBMan scheduling), so the DPCON allocator is
> moved from the event driver to the fslmc bus and shared.
> 
> Patch 1 disables the DPCON channel before closing it, an event/dpaa2 fix
> the shared allocator depends on. Patches 2 to 4 move the DPCON allocator
> to the fslmc bus, make the portal DQRI epoll optional, and add the
> dpcon_set_notification MC command. Patch 5 adds the interrupt support
> proper; patch 6 pins each DPIO's MSI to the lcore that arms it, a latency
> optimisation.
> 
> Tested on LX2160A (lx2160acex7).
> 
> v3:
> - Reworked the Rx drain. Both versions bind one DPCON per FQ, but v2
>   drained the shared portal DQRR and demuxed frames to their FQ by
>   fqd_ctx, stashing foreign frames in a per-queue FIFO. v3 drains each
>   queue with a volatile dequeue on its own channel (one FQ per channel),
>   which drops the demux and stash code.
> - Dropped the rx_queue_count fix; it is applied to main.
> - Dropped the software VLAN strip patch; an independent net/dpaa2 cleanup,
>   sent standalone and now applied to next-net.
> - Dropped the Depends-on: the ethdev fast-path ops fix is now in main.
> - Split the dpcon_set_notification MC command into its own patch.
> - Added an event/dpaa2 fix to disable the DPCON channel before close,
>   needed once the allocator is shared.
> - Dropped the DQRI holdoff-tuning patch; the immediate-DQRI holdoff is now
>   set inline in the arm path.
> - Added a patch reusing the event driver's MSI-affinity helper (exposed
>   from its RTE_EVENT_DPAA2 guard) to pin the portal MSI to the lcore that
>   arms it, so a CDAN wake lands on the worker's own core.
> 
> v2:
> - Dropped the RSS RETA patch, an independent net/dpaa2 change the
>   interrupt path does not require; it will be sent as its own series.
> - Dropped the ethdev fast-path ops fix; it is now a standalone series.
> - Dropped the eal/interrupts -EEXIST fix, applied to main by David
>   Marchand.
> - Declared qbman_swp_interrupt_set_inhibit and qbman_swp_dqrr_size
>   __rte_internal (David Marchand).
> - Minor formatting cleanup in the Rx interrupt setup.
> 
> Maxime Leroy (6):
>   event/dpaa2: disable channel before closing it
>   bus/fslmc: move DPCON management from event driver to bus
>   bus/fslmc/dpio: make the portal DQRI epoll optional
>   bus/fslmc/mc: implement dpcon_set_notification
>   net/dpaa2: support Rx queue interrupts
>   net/dpaa2: pin Rx queue interrupt to the polling core
> 
>  doc/guides/nics/dpaa2.rst                     |  21 +
>  doc/guides/nics/features/dpaa2.ini            |   1 +
>  doc/guides/rel_notes/release_26_07.rst        |   1 +
>  drivers/bus/fslmc/mc/dpcon.c                  |  31 ++
>  drivers/bus/fslmc/mc/fsl_dpcon.h              |  18 +
>  drivers/bus/fslmc/meson.build                 |   1 +
>  .../fslmc/portal}/dpaa2_hw_dpcon.c            |  17 +-
>  drivers/bus/fslmc/portal/dpaa2_hw_dpio.c      | 112 ++++--
>  drivers/bus/fslmc/portal/dpaa2_hw_dpio.h      |  12 +
>  drivers/bus/fslmc/portal/dpaa2_hw_pvt.h       |  12 +
>  .../fslmc/qbman/include/fsl_qbman_portal.h    |   5 +
>  drivers/bus/fslmc/qbman/qbman_portal.c        |   5 +
>  drivers/event/dpaa2/dpaa2_eventdev.h          |   3 -
>  drivers/event/dpaa2/meson.build               |   1 -
>  drivers/net/dpaa2/dpaa2_ethdev.c              | 372 +++++++++++++++++-
>  drivers/net/dpaa2/dpaa2_ethdev.h              |   4 +
>  drivers/net/dpaa2/dpaa2_rxtx.c                | 104 +++--
>  17 files changed, 649 insertions(+), 71 deletions(-)
>  rename drivers/{event/dpaa2 => bus/fslmc/portal}/dpaa2_hw_dpcon.c (88%)
> 
> 
> base-commit: 030328f5f920a87dabde54dacd4f5ac411ddcac9

Looks good, applied to net-next