linux-kernel - Re: [PATCH net-next 05/15] net: dsa: mt7530: improve code path for setting up port 5

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Message-ID: <ZVjNJ0nf7Mp0kHzH@shell.armlinux.org.uk>
Date:   Sat, 18 Nov 2023 14:41:43 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Arınç ÜNAL <arinc.unal@...nc9.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>,
        Vladimir Oltean <olteanv@...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>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Bartel Eerdekens <bartel.eerdekens@...stell8.be>,
        mithat.guner@...ont.com, erkin.bozoglu@...ont.com
Subject: Re: [PATCH net-next 05/15] net: dsa: mt7530: improve code path for
 setting up port 5

On Sat, Nov 18, 2023 at 03:31:55PM +0300, Arınç ÜNAL wrote:
> There're two code paths for setting up port 5:
> 
> mt7530_setup()
> -> mt7530_setup_port5()
> 
> mt753x_phylink_mac_config()
> -> mt753x_mac_config()
>    -> mt7530_mac_config()
>       -> mt7530_setup_port5()
> 
> Currently mt7530_setup_port5() from mt7530_setup() always runs. If port 5
> is used as a CPU, DSA, or user port, mt7530_setup_port5() from
> mt753x_phylink_mac_config() won't run. That is because priv->p5_interface
> set on mt7530_setup_port5() will match state->interface on
> mt753x_phylink_mac_config() which will stop running mt7530_setup_port5()
> again.
> 
> Therefore, mt7530_setup_port5() will never run from
> mt753x_phylink_mac_config().
> 
> Address this by not running mt7530_setup_port5() from mt7530_setup() if
> port 5 is used as a CPU, DSA, or user port. This driver isn't in the
> dsa_switches_apply_workarounds[] array so phylink will always be present.
> 
> For the cases of PHY muxing or the port being disabled, call
> mt7530_setup_port5() from mt7530_setup(). mt7530_setup_port5() from
> mt753x_phylink_mac_config() won't run when port 5 is disabled or used for
> PHY muxing as port 5 won't be defined on the devicetree.

... and this should state why this needs to happen - in other words,
the commit message should state why is it critical that port 5 is
always setup.

-- 
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