[PATCH net-next 00/13] Add tc-taprio support for queueMaxSDU

[Vladimir Oltean]

Michael and Xiaoliang will probably be aware that the tc-taprio offload
mode supported by the Felix DSA driver has limitations surrounding its
guard bands.

The initial discussion was at:
https://lore.kernel.org/netdev/c7618025da6723418c56a54fe4683bd7@xxxxxxxx/

with the latest status being that we now have a vsc9959_tas_guard_bands_update()
method which makes a best-guess attempt at how much useful space to
reserve for packet scheduling in a taprio interval, and how much to
reserve for guard bands.

IEEE 802.1Q actually does offer a tunable variable (queueMaxSDU) which
can determine the max MTU supported per traffic class. In turn we can
determine the size we need for the guard bands, depending on the
queueMaxSDU. This way we can make the guard band of small taprio
intervals smaller than one full MTU worth of transmission time, if we
know that said traffic class will transport only smaller packets.

Allow input of queueMaxSDU through netlink into tc-taprio, offload it to
the hardware I have access to (LS1028A), and deny non-default values to
everyone else.

First 3 patches are some cleanups I made while figuring out what exactly
gets called for taprio software mode, and what gets called for offload
mode.

Vladimir Oltean (13):
  net/sched: taprio: remove redundant FULL_OFFLOAD_IS_ENABLED check in
    taprio_enqueue
  net/sched: taprio: stop going through private ops for dequeue and peek
  net/sched: taprio: add extack messages in taprio_init
  net/sched: taprio: allow user input of per-tc max SDU
  net: dsa: felix: offload per-tc max SDU from tc-taprio
  net: enetc: cache accesses to &priv->si->hw
  net: enetc: offload per-tc max SDU from tc-taprio
  net: dsa: hellcreek: deny tc-taprio changes to per-tc max SDU
  net: dsa: sja1105: deny tc-taprio changes to per-tc max SDU
  tsnep: deny tc-taprio changes to per-tc max SDU
  igc: deny tc-taprio changes to per-tc max SDU
  net: stmmac: deny tc-taprio changes to per-tc max SDU
  net: am65-cpsw: deny tc-taprio changes to per-tc max SDU

 drivers/net/dsa/hirschmann/hellcreek.c        |   5 +
 drivers/net/dsa/ocelot/felix_vsc9959.c        |  20 +-
 drivers/net/dsa/sja1105/sja1105_tas.c         |   6 +-
 drivers/net/ethernet/engleder/tsnep_tc.c      |   6 +-
 drivers/net/ethernet/freescale/enetc/enetc.c  |  28 ++-
 drivers/net/ethernet/freescale/enetc/enetc.h  |  12 +-
 .../net/ethernet/freescale/enetc/enetc_pf.c   |  25 ++-
 .../net/ethernet/freescale/enetc/enetc_qos.c  |  70 +++----
 drivers/net/ethernet/intel/igc/igc_main.c     |   6 +-
 .../net/ethernet/stmicro/stmmac/stmmac_tc.c   |   6 +-
 drivers/net/ethernet/ti/am65-cpsw-qos.c       |   6 +-
 include/net/pkt_sched.h                       |   1 +
 include/uapi/linux/pkt_sched.h                |  11 +
 net/sched/sch_taprio.c                        | 194 +++++++++++++-----
 14 files changed, 283 insertions(+), 113 deletions(-)

-- 
2.34.1