Re: [PATCH v2 2/3] dts: add TX offload capabilities to NIC capabilities

[Luca Vizzarro <luca.vizzarro@arm.com>]

Copying reply from v1.

On Wed, Sep 03, 2025 at 02:04:13PM +0000, Andrew Bailey wrote:
> diff --git a/dts/framework/remote_session/testpmd_shell.py b/dts/framework/remote_session/testpmd_shell.py
> index 4d9caceb37..dfd83ebdb3 100644
> --- a/dts/framework/remote_session/testpmd_shell.py
> +++ b/dts/framework/remote_session/testpmd_shell.py
> @@ -1285,6 +1285,99 @@ class TestPmdVerbosePacket(TextParser):
>      )
>  
>  
> +class TxOffloadCapability(Flag):
> +    """TX offload capabilities of a device.
> +
> +    The flags are taken from ``lib/ethdev/rte_ethdev.h``.
> +    They're prefixed with ``RTE_ETH_TX_OFFLOAD`` in ``lib/ethdev/rte_ethdev.h``
> +    instead of ``TX_OFFLOAD``, which is what testpmd changes the prefix to.
> +    The values are not contiguous, so the correspondence is preserved
> +    by specifying concrete values interspersed between auto() values.
> +
> +    The ``TX_OFFLOAD`` prefix has been preserved so that the same flag names can be used
> +    in :class:`NicCapability`. The prefix is needed in :class:`NicCapability` since there's
> +    no other qualifier which would sufficiently distinguish it from other capabilities.
> +
> +    References:
> +        DPDK lib: ``lib/ethdev/rte_ethdev.h``
> +        testpmd display function: ``app/test-pmd/cmdline.c:print_rx_offloads()``
> +    """
> +
> +    TX_OFFLOAD_VLAN_INSERT = auto()
> +    TX_OFFLOAD_IPV4_CKSUM = auto()
> +    TX_OFFLOAD_UDP_CKSUM = auto()
> +    TX_OFFLOAD_TCP_CKSUM = auto()
> +    TX_OFFLOAD_SCTP_CKSUM = auto()
> +    TX_OFFLOAD_TCP_TSO = auto()
> +    TX_OFFLOAD_UDP_TSO = auto()
> +    TX_OFFLOAD_OUTER_IPV4_CKSUM = auto()
> +    TX_OFFLOAD_QINQ_INSERT = auto()
> +    TX_OFFLOAD_VXLAN_TNL_TSO = auto()
> +    TX_OFFLOAD_GRE_TNL_TSO = auto()
> +    TX_OFFLOAD_IPIP_TNL_TSO = auto()
> +    TX_OFFLOAD_GENEVE_TNL_TSO = auto()
> +    TX_OFFLOAD_MACSEC_INSERT = auto()
> +    TX_OFFLOAD_MT_LOCKFREE = auto()
> +    TX_OFFLOAD_MULTI_SEGS = auto()
> +    TX_OFFLOAD_MBUF_FAST_FREE = auto()
> +    TX_OFFLOAD_SECURITY = auto()
> +    TX_OFFLOAD_UDP_TNL_TSO = auto()
> +    TX_OFFLOAD_IP_TNL_TSO = auto()
> +    TX_OFFLOAD_OUTER_UDP_CKSUM = auto()
> +    TX_OFFLOAD_SEND_ON_TIMESTAMP = auto()
> +
> +    @classmethod
> +    def from_string(cls, line: str) -> Self:
> +        """Make an instance from a string containing the flag names separated with a space.
> +
> +        Args:
> +            line: The line to parse.
> +
> +        Returns:
> +            A new instance containing all found flags.
> +        """
> +        flag = cls(0)
> +        for flag_name in line.split():
> +            flag |= cls[f"TX_OFFLOAD_{flag_name}"]
> +        return flag
> +
> +    @classmethod
> +    def make_parser(cls, per_port: bool) -> ParserFn:
> +        """Make a parser function.
> +
> +        Args:
> +            per_port: If :data:`True`, will return capabilities per port. If :data:`False`,
> +                will return capabilities per queue.
> +
> +        Returns:
> +            ParserFn: A dictionary for the `dataclasses.field` metadata argument containing a
> +                parser function that makes an instance of this flag from text.
> +        """
> +        granularity = "Port" if per_port else "Queue"
> +        return TextParser.wrap(
> +            TextParser.find(rf"Per {granularity}\s+:(.*)$", re.MULTILINE),
> +            cls.from_string,
> +        )

The above is creating a lot of duplication. I'd personally implement the
functions in a class that the flags RxOffload and TxOffload can inherit
from. You can deal with `cls[f"TX_OFFLOAD_{flag_name}"]` by introducing
a "PREFIX" ClassVar for all the classes where you can specify it:

    PREFIX: ClassVar[str] = "TX_OFFLOAD_"

    ...

    cls[f"{cls.PREFIX}{flag_name}"]