[U-Boot] [PATCH 1/6] net: gem: Add support for reading MAC from I2C EEPROM

[Bin Meng]

Hi Michal,

On Sun, Feb 14, 2016 at 6:03 PM, Michal Simek <monstr at monstr.eu> wrote:
> Hi Bin,
>
> 2016-02-14 3:25 GMT+01:00 Bin Meng <bmeng.cn at gmail.com>:
>>
>> Hi Michal,
>>
>> On Sat, Feb 13, 2016 at 6:39 PM, Michal Simek <monstr at monstr.eu> wrote:
>> > Add support for reading MAC address from I2C EEPROM.
>> >
>>
>> Is this a feature provided by the GEM MAC IP?
>>
>> > Signed-off-by: Michal Simek <monstr at monstr.eu>
>> > ---
>> >
>> >  drivers/net/zynq_gem.c | 16 ++++++++++++++++
>> >  1 file changed, 16 insertions(+)
>> >
>> > diff --git a/drivers/net/zynq_gem.c b/drivers/net/zynq_gem.c
>> > index b3821c31a91d..ace60c901cb5 100644
>> > --- a/drivers/net/zynq_gem.c
>> > +++ b/drivers/net/zynq_gem.c
>> > @@ -627,6 +627,21 @@ static int zynq_gem_remove(struct udevice *dev)
>> >         return 0;
>> >  }
>> >
>> > +static int zynq_gem_read_rom_hwaddr(struct udevice *dev)
>> > +{
>> > +#if defined(CONFIG_ZYNQ_GEM_EEPROM_ADDR) && \
>> > +    defined(CONFIG_ZYNQ_GEM_I2C_MAC_OFFSET)
>> > +       struct eth_pdata *pdata = dev_get_platdata(dev);
>> > +
>> > +       if (eeprom_read(CONFIG_ZYNQ_GEM_EEPROM_ADDR,
>> > +                       CONFIG_ZYNQ_GEM_I2C_MAC_OFFSET,
>> > +                       pdata->enetaddr, ARRAY_SIZE(pdata->enetaddr)))
>>
>> This call to eeprom_read() looks to me a board-specific feature, that
>> an on-board eeprom is used to store the MAC address for the GEM?
>>
>
> Right. it is board specific feature I can
> The question is if this should really go to board specific file
> or to be the part of DT binding. I didn't look at the kernel if someone has
> some sort of eeprom binding for this case
> but I expect local mac addresses via DT are used. Or passing via command
> line does it.
>
> Anyway there is mac_read_from_eeprom() but it is ancient one.
> Do you any preference for the name of function?

I think the intention of the read_rom_hwaddr op is to read the MAC
address via the ethernet controller defined mechanism (eg: e1000 can
read its MAC address from either an EEPROM or an SPI flash), or via
SoC defined mechanism (eg: the ethernet IP is only seen on a specific
SoC, and reading the MAC address only makes sense on that specific
SoC). If this is a board-specific mechanism, I don't think we should
put the codes into driver's read_rom_hwaddr(). Again, if it is
board-specific, we may not come up with a standard DT binding for such
stuff, unless we can enumerate all possible ways for storing MAC
address on a board (EEPROM, SPI flash, eMMC, SD)?

Regards,
Bin