imx6 nand: dbbt version/layout

[Sascha Hauer]

Hi Leif,

On Thu, Apr 22, 2021 at 12:13:59PM +0000, Middelschulte, Leif wrote:
> Hi,
> 
> I'm in the process of fixing up imx-kobs to support
> - boot configuration dumps
> - boot stream extracts/updates
> on iMX6QDL using the GPMI-NAND interface, as provided by some more
> "recent" kernels.
> 
> I updated barebox on the NAND flash storage using another instance of
> barebox. Now it turns out that the dbbt version used (i.e. written) by
> barebox and supported by imx-kobs (as it was) is not documented in the
> i.MX6 QDL reference manual.
> Barebox uses[0] DBBT version 0x1000000, while the reference manual
> describes (i.MX6DQRM Rev 3., section 8.5.2.4) layout version 0x1.

It's stored in big endian. Just endianess swap 0x01000000 and you have
your 0x00000001.

> 
> Besides that, the reference manual apparently does not describe the
> field `BBMarkerPhysicalOffsetInSpareData` at the end of the FCB
> structure. Yet again, imx-kobs and barebox are reading/writing it.

barebox doesn't actively sets the value to anything else than 0x0. I
have no idea if and how the ROM interprets this value. Indeed the name
of the field seems to be inconsistent to the reference manual.

Regards,
  Sascha


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