linux-kernel - Re: [PATCH net v2 2/7] net: dsa: mt7530: fix trapping frames with multiple CPU ports on MT7530

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Message-ID: <ca78b2f9-bf98-af26-0267-60d2638f7f00@arinc9.com>
Date:   Tue, 13 Jun 2023 20:30:28 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Daniel Golle <daniel@...rotopia.org>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Russell King <linux@...linux.org.uk>,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Bartel Eerdekens <bartel.eerdekens@...stell8.be>,
        mithat.guner@...ont.com, erkin.bozoglu@...ont.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net v2 2/7] net: dsa: mt7530: fix trapping frames with
 multiple CPU ports on MT7530

On 13.06.2023 20:24, Vladimir Oltean wrote:
> On Tue, Jun 13, 2023 at 08:18:58PM +0300, Vladimir Oltean wrote:
>> On Tue, Jun 13, 2023 at 08:14:35PM +0300, Arınç ÜNAL wrote:
>>> Actually, having only "net: dsa: introduce preferred_default_local_cpu_port
>>> and use on MT7530" backported is an enough solution for the current stable
>>> kernels.
>>>
>>> When multiple CPU ports are defined on the devicetree, the CPU_PORT bits
>>> will be set to port 6. The active CPU port will also be port 6.
>>>
>>> This would only become an issue with the changing the DSA conduit support.
>>> But that's never going to happen as this patch will always be on the kernels
>>> that support changing the DSA conduit.
>>
>> Aha, ok. I thought that device trees with CPU port 5 exclusively defined
>> also exist in the wild. If not, and this patch fixes a theoretical only
>> issue, then it is net-next material.
> 
> On second thought, compatibility with future device trees is the reason
> for this patch set, so that should equally be a reason for keeping this
> patch in a "net" series.
> 
> If I understand you correctly, port 5 should have worked since commit
> c8b8a3c601f2 ("net: dsa: mt7530: permit port 5 to work without port 6 on
> MT7621 SoC"), and it did, except for trapping, right?

That fixes port 5 on certain variants of the MT7530 switch, as it was 
already working on the other variants, which, in conclusion, fixes port 
5 on all MT7530 variants.

And no, trapping works. Having only CPU port 5 defined on the devicetree 
will cause the CPU_PORT bits to be set to port 5. There's only a problem 
when multiple CPU ports are defined.

> 
> So how about settling on that as a more modest Fixes: tag, and
> explaining clearly in the commit message what's affected?

I don't see anything to change in the patch log except addressing 
Russell's comments.

Arınç