[U-Boot] U-boot for Atmel AT91SAM9G20 problem

[U-Boot] U-boot for Atmel AT91SAM9G20 problem

[Zhong Li]

We have a strange problem running U-boot on an AT91SAM9G20 board.  The board
uses single 16 bit data bus SDRAM chip.  Everything works fine when using
32MB SDRAM chip but U-boot seems to hang when putting in a 64MB SDRAM chip.
The Atmel boot strap code was modified to have the correct row and column
settings for the SDRAM chip.  The hardware is verified to be working fine
with JTAG.  We can also boot directly to Linux from Atmel boot strap code
with some modification.  The memtester is used to verify the SDRAM working
fine after booting up Linux.  So it must be some thing between the boot
strap code and U-boot that upsets the U-boot.  Can anyone give a hint what
might be wrong?

Many thanks in advance,

ZL

[U-Boot] U-boot for Atmel AT91SAM9G20 problem

[Wolfgang Denk]

Dear "Zhong Li",

In message <022501cac18c$3b11e090$b135a1b0$@com> you wrote:
> We have a strange problem running U-boot on an AT91SAM9G20 board.  The board
> uses single 16 bit data bus SDRAM chip.  Everything works fine when using
> 32MB SDRAM chip but U-boot seems to hang when putting in a 64MB SDRAM chip.
> The Atmel boot strap code was modified to have the correct row and column
> settings for the SDRAM chip.  The hardware is verified to be working fine
> with JTAG.  We can also boot directly to Linux from Atmel boot strap code
> with some modification.  The memtester is used to verify the SDRAM working
> fine after booting up Linux.  So it must be some thing between the boot
> strap code and U-boot that upsets the U-boot.  Can anyone give a hint what
> might be wrong?

We have seen this behaviour on another system, too. Unfortunately we
didn't have enough time allowed to dig into this, combined with other
hardware issues, so we assumed it was a hardware issue eventually.

If you see the same problem again, then I guess the memory  initiali-
zation  in  the  Atmel  bootstrap  code is incorrect / incomplete and
needs to be carefully reworked.  Sorry, we don't have any such
hardware here, so we cannot help.

Best regards,

Wolfgang Denk

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