[PATCH v2 iwl-next 0/3] igc: add RSS key get/set support

[Kohei Enju <kohei@enjuk.jp>]

This series adds ethtool get/set support for the RSS hash key.

Without patch:
 # ethtool -x $DEV | grep key -A1
 RSS hash key:
 Operation not supported
 # ethtool -X $DEV hkey be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef
 Cannot set RX flow hash configuration:
  Hash key setting not supported

With patch:
 # ethtool -x $DEV | grep key -A1
 RSS hash key:
 dd:7c:1f:06:1a:42:dc:e5:7e:90:2c:48:aa:3f:5d:5a:d7:da:ec:44:3e:3f:df:78:89:1e:3c:68:2e:59:da:a0:23:5a:32:5c:cf:5e:7e:7b
 # ethtool -X $DEV hkey be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef
 # ethtool -x $DEV | grep key -A1
 RSS hash key:
 be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef:be:ef

Also tested with rss_api.py and toeplitz.py.
 # ./tools/testing/selftests/drivers/net/hw/rss_api.py | grep rss_api.test_rxfh_nl_set_key
 ok 6 rss_api.test_rxfh_nl_set_key
 # tools/testing/selftests/drivers/net/hw/toeplitz.py | grep "# Totals"
 # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0

Notes:
Since the 2/3 patch is unchanged, I preserved Tested-by and Reviewed-by
tags for the patch.

Changes:
  v2:
    - call netdev_rss_key_fill() in igc_sw_init(), not in
      igc_setup_mrqc()
    - add documentation for igc_write_rss_key()
    - drop has_user_rss_key flag, since rss_key is never cleared except
      for user operations
    - change email address from @amazon.com to @enjuk.jp
  v1: https://lore.kernel.org/intel-wired-lan/20251025150136.47618-1-enjuk@amazon.com/

Kohei Enju (3):
  igc: prepare for RSS key get/set support
  igc: expose RSS key via ethtool get_rxfh
  igc: allow configuring RSS key via ethtool set_rxfh

 drivers/net/ethernet/intel/igc/igc.h         |  3 +
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 67 +++++++++++++++-----
 drivers/net/ethernet/intel/igc/igc_main.c    |  8 +--
 3 files changed, 57 insertions(+), 21 deletions(-)

-- 
2.51.0