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

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Date:   Tue, 13 Jun 2023 19:29:18 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Arınç ÜNAL <arinc.unal@...nc9.com>
Cc:     Vladimir Oltean <olteanv@...il.com>,
        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>,
        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 Tue, Jun 13, 2023 at 08:58:33PM +0300, Arınç ÜNAL wrote:
> On 13.06.2023 20:39, Vladimir Oltean wrote:
> > On Tue, Jun 13, 2023 at 08:30:28PM +0300, Arınç ÜNAL wrote:
> > > 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.
> > 
> > Ok. I didn't pay enough attention to the commit message.
> > 
> > > 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.
> > 
> > Got it. Then this is really not a problem, and the commit message frames
> > it incorrectly.
> 
> Actually this patch fixes the issue it describes. At the state of this
> patch, when multiple CPU ports are defined, port 5 is the active CPU port,
> CPU_PORT bits are set to port 6.

Maybe it's just me being dumb, but I keep finding things difficult to
understand, such as the above paragraph.

It sounds like you're saying that _before_ this patch, port 5 is the
active CPU port, but the CPU_PORT *FIELD* NOT BITS are set such that
port 6 is the active CPU port. Therefore, things are broken, and this
patch fixes it.

Or are you saying that after this patch is applied, port 5 is the
active CPU port, but the CPU_PORT *FIELD* is set to port 6. If that's
true, then I've no idea what the hell is going on here because it
seems to be senseless.

I think at this point I just give up trying to understand what the
hell these patches are trying to do - in my opinion, the commit
messages are worded attrociously and incomprehensively.

-- 
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