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From:   Alexander Stein <alexander.stein@ew.tq-group.com>
To:     netdev@vger.kernel.org, Heiko Schocher <heiko.schocher@gmail.com>
Cc:     Heiko Schocher <hs@denx.de>, Clark Wang <xiaoning.wang@nxp.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        NXP Linux Team <linux-imx@nxp.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Shenwei Wang <shenwei.wang@nxp.com>,
        Wei Fang <wei.fang@nxp.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: fec: fix probing of fec1 when fec0 is not probed yet
Date:   Thu, 23 Nov 2023 16:11:40 +0100
Message-ID: <5992842.lOV4Wx5bFT@steina-w>
Organization: TQ-Systems GmbH
In-Reply-To: <20231123132744.62519-1-hs@denx.de>
References: <20231123132744.62519-1-hs@denx.de>
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Hello Heiko,

Am Donnerstag, 23. November 2023, 14:27:43 CET schrieb Heiko Schocher:
> it is possible that fec1 is probed before fec0. On SoCs
> with FEC_QUIRK_SINGLE_MDIO set (which means fec1 uses mii
> from fec0) init of mii fails for fec1 when fec0 is not yet
> probed, as fec0 setups mii bus. In this case fec_enet_mii_init
> for fec1 returns with -ENODEV, and so fec1 never comes up.
>=20
> Return here with -EPROBE_DEFER so interface gets later
> probed again.
>=20
> Found this on imx8qxp based board, using 2 ethernet interfaces,
> and from time to time, fec1 interface came not up.

But FEC_QUIRK_SINGLE_MDIO is only set for imx28. How is this related to=20
imx8qxp?
Will this also help for imx6ul when fec1 is almost always probed before fec=
0=20
due to order of DT nodes?

Best regards,
Alexander

> Signed-off-by: Heiko Schocher <hs@denx.de>
> ---
>=20
>  drivers/net/ethernet/freescale/fec_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c index
> c3b7694a7485..d956f95e7a65 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -2445,7 +2445,7 @@ static int fec_enet_mii_init(struct platform_device
> *pdev) mii_cnt++;
>  			return 0;
>  		}
> -		return -ENOENT;
> +		return -EPROBE_DEFER;
>  	}
>=20
>  	bus_freq =3D 2500000; /* 2.5MHz by default */


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