tc-taprio can select whether traffic classes are express or preemptible.

0) tc qdisc add dev eth1 parent root handle 100 taprio \
        num_tc 4 \
        map 0 1 2 3 2 2 2 2 2 2 2 2 2 2 2 3 \
        queues 1@0 1@1 1@2 1@3 \
        base-time 1000000000 \
        sched-entry S 03 10000000 \
        sched-entry S 0e 10000000 \
        flags 0x2 fp P E E E

1) After some traffic tests, MAC merge layer statistics are all good.

Local device:
[ {
        "ifname": "eth1",
        "pmac-enabled": true,
        "tx-enabled": true,
        "tx-active": true,
        "tx-min-frag-size": 60,
        "rx-min-frag-size": 60,
        "verify-enabled": true,
        "verify-time": 100,
        "max-verify-time": 128,
        "verify-status": "SUCCEEDED",
        "statistics": {
            "MACMergeFrameAssErrorCount": 0,
            "MACMergeFrameSmdErrorCount": 0,
            "MACMergeFrameAssOkCount": 0,
            "MACMergeFragCountRx": 0,
            "MACMergeFragCountTx": 17837,
            "MACMergeHoldCount": 18639
        }
    } ]

Remote device:
[ {
        "ifname": "end1",
        "pmac-enabled": true,
        "tx-enabled": true,
        "tx-active": true,
        "tx-min-frag-size": 60,
        "rx-min-frag-size": 60,
        "verify-enabled": true,
        "verify-time": 100,
        "max-verify-time": 128,
        "verify-status": "SUCCEEDED",
        "statistics": {
            "MACMergeFrameAssErrorCount": 0,
            "MACMergeFrameSmdErrorCount": 0,
            "MACMergeFrameAssOkCount": 17189,
            "MACMergeFragCountRx": 17837,
            "MACMergeFragCountTx": 0,
            "MACMergeHoldCount": 0
        }
    } ]

Tested on DWMAC CORE 5.10a
Signed-off-by: Furong Xu <0x1207@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://patch.msgid.link/0d21ae356fb3cab77337527e87d46748a4852055.1725631883.git.0x1207@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>