linux-kernel - Re: [PATCH] net: fec: Defer probe if other FEC has deferred MDIO

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Date:   Thu, 9 Feb 2023 07:27:59 +0000
From:   "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
To:     "andrew@...n.ch" <andrew@...n.ch>
CC:     "wei.fang@....com" <wei.fang@....com>,
        "xiaoning.wang@....com" <xiaoning.wang@....com>,
        "shenwei.wang@....com" <shenwei.wang@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-imx@....com" <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: fec: Defer probe if other FEC has deferred MDIO

Hello Andrew,

On Thu, 2023-02-09 at 01:55 +0100, Andrew Lunn wrote:
> > -       if ((fep->quirks & FEC_QUIRK_SINGLE_MDIO) && fep->dev_id >
> > 0) {
> > +       if (fep->quirks & FEC_QUIRK_SINGLE_MDIO) {
> >                 /* fec1 uses fec0 mii_bus */
> >                 if (mii_cnt && fec0_mii_bus) {
> >                         fep->mii_bus = fec0_mii_bus;
> >                         mii_cnt++;
> >                         return 0;
> >                 }
> > -               return -ENOENT;
> 
> Could you not add an else clause here? return -EPROBE_DEFFER?
> 
> Basically, if fec0 has not probed, deffer the probing of fec1?

we do have a configuration with i.MX8 where we have only fec2 enabled
(and has mdio node).
I'm not sure if it was thought of by fec driver developers (it makes
a lot of non-obvious assumtions), but that's how it works now. 

-- 
Alexander Sverdlin
Siemens AG
www.siemens.com