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SubjectRe: [PATCH v3 3/3] net: ethernet: add ag71xx driver
On Sat, May 04, 2019 at 11:40:53PM +0800, Chuanhong Guo wrote:
> Hi!
>
> On Mon, Apr 22, 2019 at 9:28 PM Andrew Lunn <andrew@lunn.ch> wrote:
> > [...]
> > > + /*
> > > + * On most (all?) Atheros/QCA SoCs dual eth interfaces are not equal.
> > > + *
> > > + * That is to say eth0 can not work independently. It only works
> > > + * when eth1 is working.
> > > + */
> >
> > Please could you explain that some more? Is there just one MDIO bus
> > shared by two ethernet controllers? If so, it would be better to have
> > the MDIO bus controller as a separate driver.
>
> mdio registers exists on both ethernet blocks. And due to how reset
> works on this ethernet IP, it's hard to split it into a separated
> driver. (Only asserting both eth and mdio resets together will reset
> everything including register values.)
> The reason why gmac1 should be brought up first is that on some chips,
> mdio on gmac0 connects to nothing and phy used by gmac0 is on mdio bus
> of gmac1.

It could be implemented as mfd device. Not sure if it is worth it.
Pro/contra argumentation is welcome.

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