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

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Date:   Tue, 29 Aug 2017 17:12:45 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Adam Ford <aford173@...il.com>
CC:     Tony Lindgren <tony@...mide.com>,
        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 03:53 PM, Adam Ford wrote:
> On Tue, Aug 29, 2017 at 3:23 AM, Sekhar Nori <nsekhar@...com> wrote:
>> 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.
> 
> Thanks for doing that.
> 
>>
>> Adam, if I can get your Tested-by, I will make an attempt to send it for
>> v4.13 itself.
> 
> I will test it.  Do need to run some instruction or do something
> special in U-Boot to pass this in the proper place for the kernel to
> pull it?  Tony's patch reference showed
> command for fdt set, but I am not sure I fully understand the
> parameters that went along with that.

Nope, just applying the patch and booting the with the new dtb should
result in the random mac address going away.

Thanks,
Sekhar