linux-kernel - Re: [PATCH net-next v2] net: bcmgenet: Generate a random MAC if none is valid

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Date:   Tue, 15 Oct 2019 15:32:28 -0700
From:   Scott Branden <scott.branden@...adcom.com>
To:     Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org
Cc:     phil@...pberrypi.org, jonathan@...pberrypi.org,
        matthias.bgg@...nel.org, linux-rpi-kernel@...ts.infradead.org,
        wahrenst@....net, nsaenzjulienne@...e.de,
        Doug Berger <opendmb@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:BROADCOM GENET ETHERNET DRIVER" 
        <bcm-kernel-feedback-list@...adcom.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v2] net: bcmgenet: Generate a random MAC if none
 is valid

Hi Florian,

On 2019-10-14 2:20 p.m., Florian Fainelli wrote:
> Instead of having a hard failure and stopping the driver's probe
> routine, generate a random Ethernet MAC address to keep going.
>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
> Changes in v2:
>
> - provide a message that a random MAC is used, the same message that
>    bcmsysport.c uses
>
>   drivers/net/ethernet/broadcom/genet/bcmgenet.c | 17 ++++++++---------
>   1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> index 12cb77ef1081..dd4e4f1dd384 100644
> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
> @@ -3461,16 +3461,10 @@ static int bcmgenet_probe(struct platform_device *pdev)
>   		goto err;
>   	}
>   
> -	if (dn) {
> +	if (dn)
>   		macaddr = of_get_mac_address(dn);
> -		if (IS_ERR(macaddr)) {
> -			dev_err(&pdev->dev, "can't find MAC address\n");
> -			err = -EINVAL;
> -			goto err;
> -		}
> -	} else {
> +	else
>   		macaddr = pd->mac_address;
> -	}
>   
>   	priv->base = devm_platform_ioremap_resource(pdev, 0);
>   	if (IS_ERR(priv->base)) {
> @@ -3482,7 +3476,12 @@ static int bcmgenet_probe(struct platform_device *pdev)
>   
>   	SET_NETDEV_DEV(dev, &pdev->dev);
>   	dev_set_drvdata(&pdev->dev, dev);
> -	ether_addr_copy(dev->dev_addr, macaddr);
> +	if (IS_ERR_OR_NULL(macaddr) || !is_valid_ether_addr(macaddr)) {
> +		dev_warn(&pdev->dev, "using random Ethernet MAC\n");
I would still consider this warrants a dev_err as you should not be 
using the device with a random MAC address assigned to it.  But I'll 
leave it to the "experts" to decide on the print level here.
> +		eth_hw_addr_random(dev);
> +	} else {
> +		ether_addr_copy(dev->dev_addr, macaddr);
> +	}
>   	dev->watchdog_timeo = 2 * HZ;
>   	dev->ethtool_ops = &bcmgenet_ethtool_ops;
>   	dev->netdev_ops = &bcmgenet_netdev_ops;