netdev - Re: Fwd: DA850-evm MAC Address is random

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Date:   Tue, 29 Aug 2017 13:53:12 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Tony Lindgren <tony@...mide.com>, Adam Ford <aford173@...il.com>
CC:     Grygorii Strashko <grygorii.strashko@...com>,
        <linux-omap@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: Re: Fwd: DA850-evm MAC Address is random

On Tuesday 29 August 2017 02:42 AM, Tony Lindgren wrote:
> * Adam Ford <aford173@...il.com> [170828 13:33]:
>> On Mon, Aug 28, 2017 at 1:54 PM, Grygorii Strashko
>> <grygorii.strashko@...com> wrote:
>>> Cc: Sekhar
>>>
>>> On 08/28/2017 10:32 AM, Adam Ford wrote:
>>>>
>>>> The davinvi_emac MAC address seems to attempt a call to
>>>> ti_cm_get_macid in cpsw-common.c but it returns the message
>>>> 'davinci_emac davinci_emac.1: incompatible machine/device type for
>>>> reading mac address ' and then generates a random MAC address.
>>>>
>>>> The function appears to lookup varions boards using
>>>> 'of_machine_is_compaible' and supports dm8148, am33xx, am3517, dm816,
>>>> am4372 and dra7.  I don't see the ti,davinci-dm6467-emac which is
>>>> what's shown in the da850 device tree.
>>>>
>>>> Is there a patch somewhere for supporting the da850-evm?
>>>
>>>
>>> Not sure if MAC address can be read from Control module.
>>> May be Sekhar can say more?
>>
>> My understanding is that the MAC address is programmed by Logic PD
>> into the SPI flash.  The Bootloader reads this from either SPI or its
>> env variables.  Looking at the partition info listed in the
>> da850-evm.dts file, it appears as if they've reserved space for it.
>> Unfortunately, I don't see any code that reads it out.  I was hoping

This code is present in U-Boot sources at
board/davinci/da8xxevm/da850evm.c. See the function get_mac_addr() and
its usage in misc_init_r().

>> there might be a way to just pass cmdline parameter from the
>> bootloader to the kernel to accept the MAC address.
>>
>>>
>>>>
>>>> If not, is there a way to pass the MAC address from U-Boot to the
>>>> driver so it doesn't generate a random MAC?
>>>
>>>
>>> "local-mac-address" dt porp
>>
>> The downside here, is that we'd have to have the Bootloader modify the
>> device tree.
> 
> That piece of code exists somewhere in u-boot already. Note how

Yes, it is fdt_fixup_ethernet() and its usage is in common/image-fdt.c.

> we are populating the mac address for USB Ethernet drivers in
> u-boot and then the Ethernet driver code parses it. See commit
> 055d31de7158 ("ARM: omap3: beagleboard-xm: dt: Add ethernet to
> the device tree") for some more information.
> 
> I think u-boot needs the ethernet alias for finding the interface.

That's exactly what was missing. I have sent a patch for fixing that and
copied you there.

Adam, if I can get your Tested-by, I will make an attempt to send it for
v4.13 itself.

Thanks,
Sekhar