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Date:   Wed, 23 Sep 2020 13:31:47 -0700 (PDT)
Message-Id: <20200923.133147.842604978902817779.davem@davemloft.net>
To:     s.riedmueller@phytec.de
Cc:     fugang.duan@nxp.com, kuba@kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        c.hemp@phytec.de
Subject: Re: [PATCH] net: fec: Keep device numbering consistent with
 datasheet
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20200923142528.303730-1-s.riedmueller@phytec.de>
References: <20200923142528.303730-1-s.riedmueller@phytec.de>
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From: Stefan Riedmueller <s.riedmueller@phytec.de>
Date: Wed, 23 Sep 2020 16:25:28 +0200

> From: Christian Hemp <c.hemp@phytec.de>
> 
> Make use of device tree alias for device enumeration to keep the device
> order consistent with the naming in the datasheet.
> 
> Otherwise for the i.MX 6UL/ULL the ENET1 interface is enumerated as eth1
> and ENET2 as eth0.
> 
> Signed-off-by: Christian Hemp <c.hemp@phytec.de>
> Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>

Device naming and ordering for networking devices was never, ever,
guaranteed.

Use udev or similar.

> @@ -3691,6 +3692,10 @@ fec_probe(struct platform_device *pdev)
>  
>  	ndev->max_mtu = PKT_MAXBUF_SIZE - ETH_HLEN - ETH_FCS_LEN;
>  
> +	eth_id = of_alias_get_id(pdev->dev.of_node, "ethernet");
> +	if (eth_id >= 0)
> +		sprintf(ndev->name, "eth%d", eth_id);

You can't ever just write into ndev->name, what if another networking
device is already using that name?

This change is incorrect on many levels.