netdev - Re: [PATCH] ethernet: aquantia: Try MAC address from device tree

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Date:   Mon, 29 Nov 2021 23:11:58 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Tianhao Chai <cth451@...il.com>,
        Igor Russkikh <irusskikh@...vell.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Hector Martin <marcan@...can.st>, Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>
Subject: Re: [PATCH] ethernet: aquantia: Try MAC address from device tree

On 28.11.2021 03:37, Tianhao Chai wrote:
> Apple M1 Mac minis (2020) with 10GE NICs do not have MAC address in the
> card, but instead need to obtain MAC addresses from the device tree. In
> this case the hardware will report an invalid MAC.
> 
> Currently atlantic driver does not query the DT for MAC address and will
> randomly assign a MAC if the NIC doesn't have a permanent MAC burnt in.
> This patch causes the driver to perfer a valid MAC address from OF (if
> present) over HW self-reported MAC and only fall back to a random MAC
> address when neither of them is valid.
> 
> Signed-off-by: Tianhao Chai <cth451@...il.com>
> ---
>  .../net/ethernet/aquantia/atlantic/aq_nic.c   | 28 ++++++++++++-------
>  1 file changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
> index 1acf544afeb4..ae6c4a044390 100644
> --- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
> +++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c
> @@ -316,18 +316,26 @@ int aq_nic_ndev_register(struct aq_nic_s *self)
>  	aq_macsec_init(self);
>  #endif
>  
> -	mutex_lock(&self->fwreq_mutex);
> -	err = self->aq_fw_ops->get_mac_permanent(self->aq_hw, addr);
> -	mutex_unlock(&self->fwreq_mutex);
> -	if (err)
> -		goto err_exit;
> +	if (eth_platform_get_mac_address(&self->pdev->dev, addr) == 0 &&
> +	    is_valid_ether_addr(addr)) {

Calling is_valid_ether_addr() shouldn't be needed here. of_get_mac_addr()
does this check already. If you should decide to keep this check:
Kernel doc of is_valid_ether_addr() states that argument must be
word-aligned. So you may need to add a __align(2) to the address char
array definition.

> +		// DT supplied a valid MAC address
> +		eth_hw_addr_set(self->ndev, addr);
> +	} else {
> +		// If DT has none or an invalid one, ask device for MAC address
> +		mutex_lock(&self->fwreq_mutex);
> +		err = self->aq_fw_ops->get_mac_permanent(self->aq_hw, addr);
> +		mutex_unlock(&self->fwreq_mutex);
>  
> -	eth_hw_addr_set(self->ndev, addr);
> +		if (err)
> +			goto err_exit;
>  
> -	if (!is_valid_ether_addr(self->ndev->dev_addr) ||
> -	    !aq_nic_is_valid_ether_addr(self->ndev->dev_addr)) {
> -		netdev_warn(self->ndev, "MAC is invalid, will use random.");
> -		eth_hw_addr_random(self->ndev);
> +		if (is_valid_ether_addr(addr) &&
> +		    aq_nic_is_valid_ether_addr(addr)) {
> +			eth_hw_addr_set(self->ndev, addr);
> +		} else {
> +			netdev_warn(self->ndev, "MAC is invalid, will use random.");
> +			eth_hw_addr_random(self->ndev);
> +		}
>  	}
>  
>  #if defined(AQ_CFG_MAC_ADDR_PERMANENT)
>