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Date:   Sun, 2 Jul 2023 16:39:21 +0200
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Subject: Re: [PATCH net 2/2] net: dsa: sja1105: always enable the send_meta
 options
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To:     Vladimir Oltean <vladimir.oltean@nxp.com>, netdev@vger.kernel.org
Cc:     Andrew Lunn <andrew@lunn.ch>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org
References: <20230629141453.1112919-1-vladimir.oltean@nxp.com>
 <20230629141453.1112919-3-vladimir.oltean@nxp.com>
From:   Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <20230629141453.1112919-3-vladimir.oltean@nxp.com>
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On 6/29/2023 4:14 PM, Vladimir Oltean wrote:
> incl_srcpt has the limitation, mentioned in commit b4638af8885a ("net:
> dsa: sja1105: always enable the INCL_SRCPT option"), that frames with a
> MAC DA of 01:80:c2:xx:yy:zz will be received as 01:80:c2:00:00:zz unless
> PTP RX timestamping is enabled.
> 
> The incl_srcpt option was initially unconditionally enabled, then that
> changed with commit 42824463d38d ("net: dsa: sja1105: Limit use of
> incl_srcpt to bridge+vlan mode"), then again with b4638af8885a ("net:
> dsa: sja1105: always enable the INCL_SRCPT option"). Bottom line is that
> it now needs to be always enabled, otherwise the driver does not have a
> reliable source of information regarding source_port and switch_id for
> link-local traffic (tag_8021q VLANs may be imprecise since now they
> identify an entire bridging domain when ports are not standalone).
> 
> If we accept that PTP RX timestamping (and therefore, meta frame
> generation) is always enabled in hardware, then that limitation could be
> avoided and packets with any MAC DA can be properly received, because
> meta frames do contain the original bytes from the MAC DA of their
> associated link-local packet.
> 
> This change enables meta frame generation unconditionally, which also
> has the nice side effects of simplifying the switch control path
> (a switch reset is no longer required on hwtstamping settings change)
> and the tagger data path (it no longer needs to be informed whether to
> expect meta frames or not - it always does).
> 
> Fixes: 227d07a07ef1 ("net: dsa: sja1105: Add support for traffic through standalone ports")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian