netdev - Re: [PATCH net-next v3 2/3] fsl/fman: tolerate missing MAC address in device tree

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Message-ID: <20200309133844.GN3335@pengutronix.de>
Date:   Mon, 9 Mar 2020 14:38:44 +0100
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     "Madalin Bucur (OSS)" <madalin.bucur@....nxp.com>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v3 2/3] fsl/fman: tolerate missing MAC address
 in device tree

On Mon, Mar 09, 2020 at 01:21:16PM +0000, Madalin Bucur (OSS) wrote:
> > -----Original Message-----
> > From: Sascha Hauer <s.hauer@...gutronix.de>
> > Sent: Monday, March 9, 2020 3:10 PM
> > To: Madalin Bucur (OSS) <madalin.bucur@....nxp.com>
> > Cc: davem@...emloft.net; netdev@...r.kernel.org
> > Subject: Re: [PATCH net-next v3 2/3] fsl/fman: tolerate missing MAC
> > address in device tree
> > 
> > On Mon, Mar 09, 2020 at 10:17:36AM +0000, Madalin Bucur (OSS) wrote:
> > > > -----Original Message-----
> > > > From: Sascha Hauer <s.hauer@...gutronix.de>
> > > > Sent: Monday, March 9, 2020 8:47 AM
> > > > To: Madalin Bucur (OSS) <madalin.bucur@....nxp.com>
> > > > Cc: davem@...emloft.net; netdev@...r.kernel.org
> > > > Subject: Re: [PATCH net-next v3 2/3] fsl/fman: tolerate missing MAC
> > > > address in device tree
> > > >
> > > > On Thu, Mar 05, 2020 at 07:08:57PM +0200, Madalin Bucur wrote:
> > > > > Allow the initialization of the MAC to be performed even if the
> > > > > device tree does not provide a valid MAC address. Later a random
> > > > > MAC address should be assigned by the Ethernet driver.
> > > > >
> > > > > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > > > > Signed-off-by: Madalin Bucur <madalin.bucur@....nxp.com>
> > > > > ---
> > > > >  drivers/net/ethernet/freescale/fman/fman_dtsec.c | 10 ++++------
> > > > >  drivers/net/ethernet/freescale/fman/fman_memac.c | 10 ++++------
> > > > >  drivers/net/ethernet/freescale/fman/fman_tgec.c  | 10 ++++------
> > > > >  drivers/net/ethernet/freescale/fman/mac.c        | 13 ++++++------
> > -
> > > > >  4 files changed, 18 insertions(+), 25 deletions(-)
> > > > >
> > > <snip>
> > > > >  	/* Get the MAC address */
> > > > >  	mac_addr = of_get_mac_address(mac_node);
> > > > > -	if (IS_ERR(mac_addr)) {
> > > > > -		dev_err(dev, "of_get_mac_address(%pOF) failed\n",
> > mac_node);
> > > > > -		err = -EINVAL;
> > > > > -		goto _return_of_get_parent;
> > > > > -	}
> > > > > -	ether_addr_copy(mac_dev->addr, mac_addr);
> > > > > +	if (IS_ERR(mac_addr))
> > > > > +		dev_warn(dev, "of_get_mac_address(%pOF) failed\n",
> > mac_node);
> > > >
> > > > Why this warning? There's nothing wrong with not providing the MAC in
> > > > the device tree.
> > > >
> > > > Sascha
> > >
> > > Actually, there is, most likely it's the result of misconfiguration so
> > one
> > > must be made aware of it.
> > 
> > In my case it's not, that's why I wanted to allow random MACs in the
> > first place ;)
> > 
> > On our hardware the MAC addresses are stored in some flash in a special
> > format. There's no need to port parsing of that format into the
> > bootloader, the existing userspace code does that well and sets the
> > desired MAC addresses, but only if the devices do not fail during probe
> > due to the lack of valid MAC addresses.
> > 
> > Sascha
> 
> What MAC address does the bootloader use then?

None. The ethernet controllers are unused in the bootloader. They are
connected to the FPGA only anyway, which doesn't even have firmware
loaded in the bootloader. We have a USB Ethernet dongle for use in the
bootloader.

Sascha

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