Re: [microblaze-uclinux] CFI Flash on 8bit bus?

[Michael Libeskind <mbl@xxxxxxxxxx>]

Can someone tell me a little bit more about the issues with the EMC core 
and C_INCLUDE_DATAWIDTH_MATCHING?  I'm actually using u-boot on an ML403 
  board and have changed the flash to be just 16 bits wide because my 
real production board will have just one flash chip.

If C_INCLUDE_DATAWIDTH_MATCHING_0 is set to 0 everything works fine and
I can read and write the flash chip as expected 16 bits at a time.

If C_INCLUDE_DATAWIDTH_MATCHING_1 is set to 1 I can no longer read/write
as 16 bits.  I end up with bit 7 of the flash stuck.  Example, In u-boot
I execute:

=> mw.w 0x68000000 0x10         (unlock)
=> mw.w 0x68000000 0x1234       (write 0x1234)
=> mw.w 0x68000000 0xff         (switch to memory array)
=> md.w 0x68000000 10           (read)
68000000: 12b4 ffff ffff ffff ffff ffff ffff ffff    ................
68000010: ffff ffff ffff ffff ffff ffff ffff ffff    ................
=>

The status right before the read would have been 0x0080 so I think that
may have something to do with the position of the stuck bit.  I have 
updated mem_state_machine.vhd and mem_steer.vhd in 
/hw/XilinxProcessorIPLib/pcores/emc_common_v2_00_a/hdl/vhdl with the 
hacked version for 16 bits and everything looks great in simulation. I 
plan on breaking out chipscope later today, but if anyone has any 
insight I would certainly appreciate it.

Thanks



Errol Terblanche wrote:
> Hi David,
> 
> Ahh, so that is why it specifically mentions "16-bit flash works with JFFS2
> filesystem". :-).
> 
> Thanks for the info.
> 
> Thanx,
> E
> 
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