linux-kernel - Re: [PATCH net-next v2] net: stmmac: don't create a MDIO bus if unnecessary

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Message-ID: <e64b14c3-4b80-4120-8cc4-9baa40cdcb75@lunn.ch>
Date:   Thu, 7 Dec 2023 22:30:23 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Andrew Halaney <ahalaney@...hat.com>
Cc:     Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH net-next v2] net: stmmac: don't create a MDIO bus if
 unnecessary

On Wed, Dec 06, 2023 at 05:46:09PM -0600, Andrew Halaney wrote:
> The stmmac_dt_phy() function, which parses the devicetree node of the
> MAC and ultimately causes MDIO bus allocation, misinterprets what
> fixed-link means in relation to the MAC's MDIO bus. This results in
> a MDIO bus being created in situations it need not be.

Please extend that with something like....

This is bad, because ....

Most 'clean' driver unconditionally create the MDIO bus. But stmmac is
not that clean, and has to keep backwards compatibility to some old
usage. I'm just wondering what this patch actually brings us, and is
it worth it. Is it fixing a real bug, or just an optimisation?

   Andrew