netdev - Re: [PATCH v2 net 10/10] net: dsa: felix: break at first CPU port during init and teardown

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Date:   Tue, 12 Oct 2021 14:31:03 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <vladimir.oltean@....com>, netdev@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>, Po Liu <po.liu@....com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Michael Walle <michael@...le.cc>,
        Rui Sousa <rui.sousa@....com>, Yangbo Lu <yangbo.lu@....com>,
        Xiaoliang Yang <xiaoliang.yang_1@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v2 net 10/10] net: dsa: felix: break at first CPU port
 during init and teardown

On 10/12/21 4:40 AM, Vladimir Oltean wrote:
> The NXP LS1028A switch has two Ethernet ports towards the CPU, but only
> one of them is capable of acting as an NPI port at a time (inject and
> extract packets using DSA tags).
> 
> However, using the alternative ocelot-8021q tagging protocol, it should
> be possible to use both CPU ports symmetrically, but for that we need to
> mark both ports in the device tree as DSA masters.
> 
> In the process of doing that, it can be seen that traffic to/from the
> network stack gets broken, and this is because the Felix driver iterates
> through all DSA CPU ports and configures them as NPI ports. But since
> there can only be a single NPI port, we effectively end up in a
> situation where DSA thinks the default CPU port is the first one, but
> the hardware port configured to be an NPI is the last one.
> 
> I would like to treat this as a bug, because if the updated device trees
> are going to start circulating, it would be really good for existing
> kernels to support them, too.
> 
> Fixes: adb3dccf090b ("net: dsa: felix: convert to the new .change_tag_protocol DSA API")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian