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Date: Wed, 05 Aug 2015 17:33:21 -0700
From: Florian Fainelli <f.fainelli@gmail.com>
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To: Stephen Hemminger <stephen@networkplumber.org>,
        Francois Romieu <romieu@fr.zoreil.com>
CC: Liviu Dudau <Liviu.Dudau@arm.com>, Mirko Lindner <mlindner@marvell.com>,
        "ryan.harkin@linaro.org" <ryan.harkin@linaro.org>,
        netdev <netdev@vger.kernel.org>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sky2: Add module parameter for passing the MAC address
References: <1438789854-29194-1-git-send-email-Liviu.Dudau@arm.com>	<20150805094057.59260077@urahara>	<20150805171652.GG20890@e106497-lin.cambridge.arm.com>	<20150805203342.GA26748@electric-eye.fr.zoreil.com> <20150805161610.3bcdde98@urahara>
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On 05/08/15 16:16, Stephen Hemminger wrote:
> Something like this:
> 
> Subject: [PATCH net-next] sky2: use random address if EEPROM is bad
> 
> On some embedded systems the EEPROM does not contain a valid MAC address.
> In that case it is better to fallback to a generated mac address and
> let init scripts fix the value later.
> 
> Reported-by: Liviu Dudau <Liviu.Dudau@arm.com>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> 
> 
> --- a/drivers/net/ethernet/marvell/sky2.c	2015-05-21 15:13:03.621126050 -0700
> +++ b/drivers/net/ethernet/marvell/sky2.c	2015-08-05 16:12:38.734534467 -0700
> @@ -4819,6 +4819,16 @@ static struct net_device *sky2_init_netd
>  		memcpy_fromio(dev->dev_addr, hw->regs + B2_MAC_1 + port * 8,
>  			      ETH_ALEN);
>  
> +	/* if the address is invalid, use a random value */
> +	if (!is_valid_ether_addr(dev->dev_addr)) {
> +		struct sockaddr sa = { AF_UNSPEC };
> +
> +		netdev_warn(dev,
> +			 "Invalid MAC address defaulting to random\n");
> +		sky2_set_mac_address(dev, &sa);
> +		dev->addr_assign_type |= NET_ADDR_RANDOM;

There is a helper for that: eth_hw_addr_random() which sets the
addr_assign_type for you and copies the address to dev->dev_addr.
-- 
Florian