Re: [PATCH net-next] net: stmmac: fix mqprio and cbs combination

[Daniel Thompson <daniel@riscstar.com>]

On Mon, Oct 12, 2026 at 11:14:06PM +0200, Lorenzo Bianconi wrote:
> 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 independent MTL settings and do
> not conflict, so drop the checks and let the combination be offloaded.
> 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>
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>

Also FWIW:
Reviewed-by: Daniel Thompson <daniel@riscstar.com>


Daniel.