net: stmmac: fix mqprio and cbs combination

The channel-mode mqprio offload and the CBS offload can currently not be
enabled at the same time. tc_mqprio_validate_chan_mode() refuses the
mqprio offload as soon as any TX queue is configured in AVB mode, and
tc_setup_cbs() refuses to enable CBS while the strict-priority scheduler
is active. As a result the combination is rejected whichever order the
two are configured in.

The strict-priority scheduler selected by the channel-mode mqprio offload
and the per-queue CBS shaper are stored in independent MTL fields on
dwmac4/EQoS cores (MTL_OPERATION_MODE.SCHALG vs MTL_ETS_CTRL.AVALG), so
the two checks are over-restrictive there. On XGMAC/XLGMAC they are not
independent: the TX scheduling algorithm and the CBS shaper share the
per-TC MTL_TCx_ETS_CONTROL.TSA field, so programming the scheduler
rewrites TSA on every queue and would disable CBS on any queue configured
in AVB mode.

Drop the checks and re-apply the AVB/CBS configuration with
stmmac_configure_cbs() after the TX algorithm is reprogrammed in
tc_mqprio_config_queue_prio() and stmmac_reset_tc_mqprio(), so the
combination is offloaded correctly on all cores. The stmmac_reinit_queues()
check is dropped as well, since a subsequent ndo_open restores the AVB
queues.

The following configuration, which was previously refused, now works:

  $ tc qdisc replace dev eth0 handle 100 parent root mqprio \
        num_tc 4 \
        map  0  0  0  0  0  1  2  3  0  0  0  0  0  0  0  0 \
        queues 1@0 1@1 1@2 1@3 mode channel hw 1
  $ tc qdisc replace dev eth0 parent 100:2 handle 102: cbs  \
        idleslope 800000 sendslope -1700000 hicredit 494    \
        locredit -1049 offload 0
  $ tc qdisc replace dev eth0 parent 100:3 handle 103: cbs  \
        idleslope 400000 sendslope -2100000 hicredit 247    \
        locredit -1296 offload 1
  $ tc qdisc replace dev eth0 parent 100:4 handle 104: cbs  \
        idleslope 200000 sendslope -2300000 hicredit 124    \
        locredit -1419 offload 1

Fixes: 47891d501e34 ("net: stmmac: add tc mqprio hw queue priority offload")
Tested-by: Daniel Thompson <daniel@riscstar.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Daniel Thompson <daniel@riscstar.com>
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
Link: https://patch.msgid.link/20261014-stmmac-mqprio-cbs-combo-v2-1-372249daa81a@oss.qualcomm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions