[U-Boot] imx: Vybrid VF610 mac address issue

[Benoît Thébaudeau]

On Wednesday, June 5, 2013 11:16:17 PM, Benoît Thébaudeau wrote:
> Hi Andy, Fabio,
> 
> On Wednesday, June 5, 2013 11:13:52 PM, Fabio Estevam wrote:
> > Hi Andy,
> > 
> > On Wed, Jun 5, 2013 at 5:54 PM, Andy Voltz <andy.voltz at timesys.com> wrote:
> > > I recently tried booting the VF610 support on the Tower board, but the
> > > mac
> > > address is reversed in Linux userspace. DHCP/BOOTP seems to work properly
> > > in u-boot.
> > >
> > > I'm booting this kernel:
> > > https://github.com/Timesys/linux-timesys/
> > > ref: 2c4ead2dd6da019f5052a69b12c8f5b6b71f8dca
> > >
> > > I haven't yet seen how the address is passed to the kernel, but our
> > > previous
> > > u-boot support does not have this issue with the same kernel. That u-boot
> > > branch is also on our github.
> > 
> > The MAC address is read in the imx_get_mac_from_fuse() function in
> > arch/arm/cpu/armv7/vf610/generic.c
> > 
> > Try printing all the elements of mac[] array in this function and
> > check if the logic is correct there.
> 
> You probably had programmed the fuses with a MAC address on your board, and
> then
> replaced the existing U-Boot with the mainline version. These 2 U-Boot-s may
> interpret the MAC fuses in a different way. Especially, note that VF610
> interprets the MAC fuses with reversed endianness compared to i.MX6 in
> mainline
> U-Boot. This is documented in doc/README.<SoC>. There may be the same
> difference
> between VF610 in mainline U-Boot and the other version of U-Boot that you
> used
> first.

But if there is such a difference between U-Boot editions, it might be worth
considering to make mainline U-Boot more consistent with Freescale's or others'
before it is too much widespread. It is especially important if people change
the U-Boot edition on their board.

Stefano, Alison, what do you think?

Alison, have you checked if your implementation in mainline is consistent with
Freescale's? There may be a difference both for which fuse word is used for
high/low parts of the MAC address (i.e. word-level endianness that I was talking
about above), and for the byte-level endianness inside each fuse word.

Best regards,
Benoît