netdev - Re: [PATCH v2] fsl/fman: Use random MAC address when none is given

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Message-ID: <20200305144809.GW3335@pengutronix.de>
Date:   Thu, 5 Mar 2020 15:48:09 +0100
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Madalin Bucur <madalin.bucur@....com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v2] fsl/fman: Use random MAC address when none is given

On Thu, Mar 05, 2020 at 01:38:01PM +0000, Madalin Bucur wrote:
> > -----Original Message-----
> > From: Sascha Hauer <s.hauer@...gutronix.de>
> > Sent: Thursday, March 5, 2020 2:34 PM
> > To: netdev@...r.kernel.org
> > Cc: Madalin Bucur <madalin.bucur@....com>; Sascha Hauer
> > <s.hauer@...gutronix.de>
> > Subject: [PATCH v2] fsl/fman: Use random MAC address when none is given
> > 
> > There's no need to fail probing when no MAC address is given in the
> > device tree, just use a random MAC address.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > ---
> > 
> > Changes since v1:
> > - Remove printing of permanent MAC address
> > 
> >  drivers/net/ethernet/freescale/dpaa/dpaa_eth.c   | 11 +++++++++--
> >  drivers/net/ethernet/freescale/fman/fman_memac.c |  4 ----
> >  drivers/net/ethernet/freescale/fman/mac.c        | 10 ++--------
> >  3 files changed, 11 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > index fd93d542f497..fc117eab788d 100644
> > --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > @@ -233,8 +233,15 @@ static int dpaa_netdev_init(struct net_device
> > *net_dev,
> >  	net_dev->features |= net_dev->hw_features;
> >  	net_dev->vlan_features = net_dev->features;
> > 
> > -	memcpy(net_dev->perm_addr, mac_addr, net_dev->addr_len);
> > -	memcpy(net_dev->dev_addr, mac_addr, net_dev->addr_len);
> > +	if (is_valid_ether_addr(mac_addr)) {
> > +		dev_info(dev, "FMan MAC address: %pM\n", mac_addr);
> > +		memcpy(net_dev->perm_addr, mac_addr, net_dev->addr_len);
> > +		memcpy(net_dev->dev_addr, mac_addr, net_dev->addr_len);
> > +	} else {
> > +		eth_hw_addr_random(net_dev);
> > +		dev_info(dev, "Using random MAC address: %pM\n",
> > +			 net_dev->dev_addr);
> > +	}
> 
> To make the HW MAC aware of the new random address you set in the dpaa_eth,
> you also need to call mac_dev->change_addr() after eth_hw_addr_random(), like
> it's done in dpaa_set_mac_address():
> 
>         err = mac_dev->change_addr(mac_dev->fman_mac,
>                                    (enet_addr_t *)net_dev->dev_addr);
> 
> This will write the new MAC address in the MAC HW registers.

Ok, I see.

So when I call mac_dev->change_addr() here in dpaa_netdev_init() it
means I can remove all the code setting the MAC address in hardware
before this point, right?

Sascha

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