netdev - Re: [PATCH] net: fec: Create device link between fec0 and fec1

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Message-ID: <Y3I8qnNj1EUmPDmd@lunn.ch>
Date:   Mon, 14 Nov 2022 14:03:38 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Xiaolei Wang <xiaolei.wang@...driver.com>
Cc:     qiangqing.zhang@....com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, richardcochran@...il.com,
        lgirdwood@...il.com, broonie@...nel.org, ast@...nel.org,
        daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH] net: fec: Create device link between fec0 and fec1

On Mon, Nov 14, 2022 at 12:11:43PM +0800, Xiaolei Wang wrote:
> On imx6sx, there are two fec interfaces, but the external
> phys can only be configured by fec0 mii_bus. That means
> the fec1 can't work independently, it only work when the
> fec0 is active. It is alright in the normal boot since the
> fec0 will be probed first. But then the fec0 maybe moved
> behind of fec1 in the dpm_list due to various device link.
> So in system suspend and resume, we would get the following
> warning when configuring the external phy of fec1 via the
> fec0 mii_bus due to the inactive of fec0. In order to fix
> this issue, we create a device link between fec0 and fec1.
> This will make sure that fec0 is always active when fec1
> is in active mode.

I'm wondering if this should be more generic? I have seen this setup
more frequently on the FEC, but there are other dual MAC SoCs which
can have a similar setup, two PHYs sharing one MDIO bus.

Can this be pushed into phylib?

    Andrew