[PATCH net-next 0/3] net: bcmgenet: collapse TX priority queues

[Nicolai Buchwitz <nb@tipi-net.de>]

The strict-priority TX queues can starve under multi-queue load and
trip NETDEV_WATCHDOG. Justin's earlier series [1] tried to mitigate
the timeouts but kept the multi-queue design. Ovidiu Panait recently
proposed a WRR stop-gap [2]. This series drops the priority queues
entirely. Justin confirmed they are no longer required.

Patch 1 collapses v2-v4 hw_params to the same single-queue path v1
already uses. Patch 2 removes the now-dead priority register writes,
helper macros, and the dead "flow period for ring != 0" branch in
bcmgenet_init_tx_ring(); the DMA_ARBITER_{RR,WRR,SP} and
DMA_RING_BUF_PRIORITY_* HW defines are kept as register
documentation. Patch 3 switches the netdev allocation from
alloc_etherdev_mqs(., 5, 5) to alloc_etherdev(), since only one
TX/RX queue is ever used.

Tested on Raspberry Pi CM4 (BCM2711):
  - Ovidiu's reproducer (iperf3 -u -b0 -P16 -t60) no longer trips
    NETDEV_WATCHDOG.
  - UDP sustains 956 Mbit/s line rate over 60 s with 0 datagrams
    lost (0/4952890).
  - Single-stream TCP throughput unchanged at 943 Mbit/s.

[1] https://lore.kernel.org/netdev/20260406175756.134567-1-justin.chen@broadcom.com/
[2] https://lore.kernel.org/netdev/20260610085238.56300-1-ovidiu.panait.rb@renesas.com/

Nicolai Buchwitz (3):
  net: bcmgenet: collapse TX priority queues to a single queue
  net: bcmgenet: remove dead priority queue plumbing
  net: bcmgenet: allocate a single-queue netdev

 .../net/ethernet/broadcom/genet/bcmgenet.c    | 100 +++---------------
 .../net/ethernet/broadcom/genet/bcmgenet.h    |   2 -
 2 files changed, 16 insertions(+), 86 deletions(-)

-- 
2.53.0