netdev - Re: [PATCH 2/3] net: dsa: b53: mmap: register MDIO Mux bus controller

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Message-ID: <721af394-9ed7-477a-8b05-f8109a0d4b48@lunn.ch>
Date:   Fri, 17 Mar 2023 17:37:33 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Álvaro Fernández Rojas <noltari@...il.com>
Cc:     Vladimir Oltean <olteanv@...il.com>, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        f.fainelli@...il.com, jonas.gorski@...il.com, hkallweit1@...il.com,
        linux@...linux.org.uk, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] net: dsa: b53: mmap: register MDIO Mux bus controller

On Fri, Mar 17, 2023 at 05:30:38PM +0100, Álvaro Fernández Rojas wrote:
> El vie, 17 mar 2023 a las 17:27, Andrew Lunn (<andrew@...n.ch>) escribió:
> >
> > > > The proposed solution is too radical for a problem that was not properly
> > > > characterized yet, so this patch set has my temporary NACK.
> > >
> > > Forgive me, but why do you consider this solution too radical?
> >
> > I have to agree with Vladimir here. The problem is not the driver, but
> > when the driver is instantiated. It seems radical to remove a driver
> > just because it loads at the wrong time. Ideally you want the driver
> > to figure out now is not a good time and return -EPROBE_DEFER, because
> > a resource it requires it not available.
> 
> Ok, I'm open to suggestions.
> Any ideas on how exactly to figure out when it's a good time to probe
> or return -EPROBE_DEFER instead?

Vladimir already said:

> > > We need to know what resource belonging to the switch is it that the
> > > MDIO mux needs.

Please answer that question. Once we know what the resource is, we can
look at how to export it to the mux in a way that is safe.

       Andrew