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From:   Kurt Kanzenbach <kurt@linutronix.de>
To:     Vladimir Oltean <vladimir.oltean@nxp.com>
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Subject: Re: [PATCH net-next 08/13] net: dsa: hellcreek: deny tc-taprio
 changes to per-tc max SDU
In-Reply-To: <20220915115925.zujsneox4jqzod2g@skbuf>
References: <20220914153303.1792444-1-vladimir.oltean@nxp.com>
 <20220914153303.1792444-9-vladimir.oltean@nxp.com> <87a671bz8e.fsf@kurt>
 <20220914184051.2awuutgr4vm4tfgf@skbuf> <87r10dxiw5.fsf@kurt>
 <20220915115925.zujsneox4jqzod2g@skbuf>
Date:   Wed, 21 Sep 2022 13:23:24 +0200
Message-ID: <87bkr9m0nn.fsf@kurt>
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On Thu Sep 15 2022, Vladimir Oltean wrote:
> On Thu, Sep 15, 2022 at 08:15:54AM +0200, Kurt Kanzenbach wrote:
>> > So the maxSDU hardware register tracks exactly the L2 payload size, li=
ke
>> > the software variable does, or does it include the Ethernet header size
>> > and/or FCS?
>>=20
>> This is something I'm not sure about. I'll ask the HW engineer when he's
>> back from vacation.
>
> You can also probably figure this out by limiting the max-sdu to a value
> like 200 and seeing what frame sizes pass through.

So, configured to 128 and 132 bytes (including VLAN Ethernet header) is
the maximum frame size which passes through.

Thanks,
Kurt

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