[PATCH net-next v2 0/2] net: macb: implement ethtool set channels count operation

[Théo Lebrun]

Add support for changing the active number of queues. Tested on Mobileye
EyeQ5. The first patch is as expected. However the second one might be
more surprising:

GEM has per-queue Tx SRAM segmentation. If we do not touch SRAM
distribution then we'll only be able to exploit a portion of it when a
smaller queue count is configured. It also is beneficial if bootloader
stages write to the register and we don't reset it but attempt to use
all queues (the default).

The operation is only hidden behind MACB_CAPS_QUEUE_DISABLE, we do not
introduce yet another feature flag.

As this series must s/num_queues/max_num_queues/ quite a lot, it
conflicts with other in-flights series touching MACB in the netdev ML.
I'll make sure to resend once net-next gets updated.

Have a nice day,
Thanks,
Théo

Signed-off-by: Théo Lebrun <theo.lebrun@xxxxxxxxxxx>
---
Changes in v2:
- Move gem_sram_distribute_segments() from macb_main.c to macb_utils.c
  and kunit tests from macb_main.c to macb_kunit.c.
- macb_set_channels():
  - Add comment about MACB_CAPS_QUEUE_DISABLE.
  - Refuse operation if netif_running(), with code comment.
  - Drop useless sanity checks on ch->{combined,rx,tx}_count.
- Add help text to CONFIG_MACB_KUNIT_TEST.
- Fix `checkpatch --max-line-length=80` warnings.
- Rebase onto latest net-next; nothing to report.
- Link to v1: https://lore.kernel.org/r/20260305-macb-set-channels-v1-0-28e3a96a3dc3@xxxxxxxxxxx

---
Théo Lebrun (2):
      net: macb: implement ethtool_ops.get|set_channels()
      net: macb: distribute evenly Tx SRAM segments

 drivers/net/ethernet/cadence/Kconfig      |  13 ++++
 drivers/net/ethernet/cadence/Makefile     |   5 +-
 drivers/net/ethernet/cadence/macb.h       |   9 +++
 drivers/net/ethernet/cadence/macb_kunit.c |  73 ++++++++++++++++++
 drivers/net/ethernet/cadence/macb_main.c  | 118 ++++++++++++++++++++++++++----
 drivers/net/ethernet/cadence/macb_utils.c |  56 ++++++++++++++
 6 files changed, 257 insertions(+), 17 deletions(-)
---
base-commit: df99d268555f52fb2ac3b9fc9a6198ea0579c48a
change-id: 20260305-macb-set-channels-5bf6e07f3270

Best regards,
--  
Théo Lebrun <theo.lebrun@xxxxxxxxxxx>