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

[Benoît Thébaudeau]

Hi Alison,

On Thursday, June 6, 2013 5:36:23 AM, Wang Huan-B18965 wrote:
> Hi, Benoit,
> 
> > -----Original Message-----
> > From: Benoît Thébaudeau [mailto:benoit.thebaudeau at advansee.com]
> > Sent: Thursday, June 06, 2013 5:46 AM
> > To: Fabio Estevam
> > Cc: Andy Voltz; u-boot at lists.denx.de; Stefano Babic; Wang Huan-B18965
> > Subject: Re: [U-Boot] imx: Vybrid VF610 mac address issue
> > 
> > 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.
> [Alison Wang] Thanks for your comments. In Vybrid's RM, there is no specific
> descriptions about
> how to program the mac address in the OTP Bank4 Word2(OCOTP_MAC0) and OTP
> Bank4 Word3(OCOTP_MAC1).
> So I think it is not formulary which fuse word is used for high/low parts of
> the MAC address
> (i.e. word-level endianness), and for the byte-level endianness inside each
> fuse word.
> Through reading the doc/README.vf610, I think the user could program the
> fuses correctly.

I agree. I only had a concern if Freescale had released a VF610 BSP requiring
the MAC fuses to be programmed in a different way. According to what you said in
your previous e-mail, this is not the case, so everything is fine in mainline.

Best regards,
Benoît