netdev - Re: FEC unbind/bind feature

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Message-ID: <YF3TTZtJ1SLFkSpS@lunn.ch>
Date:   Fri, 26 Mar 2021 13:27:57 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Joakim Zhang <qiangqing.zhang@....com>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: FEC unbind/bind feature

> > Please wrap your lines at around 75 characters. Standard netiquette rules for
> > emails apply to all Linux lists.
> 
> Ok, thanks.

Please keep fighting with your email client, 

> Yes, you are right. It should be always fine for single FEC controller, and unbind/bind one by one should also be fine for dual FEC controllers which share one MDIO bus. I test on i.MX6UL, i.MX8MM/MP.
 
> > > It seems to abstract an independent MDIO bus for dual FEC instances. I
> > > look at the MDIO dt bindings, it seems support such case as it has
> > > "reg"
> > > property. (Documentation/devicetree/bindings/net/mdio.yaml)
> > 
> > You can have fully standalone MDIO bus drivers. You generally do this when the
> > MDIO bus registers are in their own address space, which you can ioremap()
> > separately from the MAC registers. Take a look in drivers/net/mdio/.
> > 
> > > From your opinions, do you think it is necessary to improve it?
> > 
> > What is you use case for unbinding/binding the FEC?
> 
> Users may want to unbind FEC driver, and then bind to FEC UIO driver, such as for DPDK use case to improve the throughput.

You could blacklist the FEC driver so it never loads. Or change the
compatible string so it only matches the DPDK driver. Or use XDP :-)

	   Andrew