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Date:   Mon, 16 Jan 2023 10:21:53 +0000
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Pierluigi Passaro <pierluigi.p@variscite.com>
Cc:     Andrew Lunn <andrew@lunn.ch>,
        Pierluigi Passaro <pierluigi.passaro@gmail.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        "hkallweit1@gmail.com" <hkallweit1@gmail.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
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        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Eran Matityahu <eran.m@variscite.com>,
        Nate Drude <Nate.D@variscite.com>,
        Francesco Ferraro <francesco.f@variscite.com>
Subject: Re: [PATCH] net: mdio: force deassert MDIO reset signal
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On Mon, Jan 16, 2023 at 09:44:01AM +0000, Pierluigi Passaro wrote:
> I can't really understand why the MDIO bus must check the PHY presence.
> Other busses try the communication only while probing the slaves,
> never before.

That is not true.

Any bus that relies on hardware identification to bind drivers reads
the identifying information prior to probing. For example, PCI, USB,
AMBA to name a few. AMBA didn't used to have this problem, but does
now - but at least under AMBA there's a bit more standardisation to
what needs to be done. With ethernet PHYs, what's needed is highly
platform specific.

-- 
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