[U-Boot-Users] minimum bdi config to read flash on 85xx

[Jerry Van Baren]

robert lazarski wrote:
> On 9/12/07, David Hawkins <dwh at ovro.caltech.edu> wrote:
>> Don't move onto anything until you can read the
>> manufacturer ID, you've found a problem, so you
>> need to figure it out here first.
> 
> After a few days with the docs, we've had some limited success. We
> moved back to 128MB of ram and a base address of F8000000 . We think
> we may have some timimg issues.

Interaction with RAM size is unexpected.  Time to quadruple check your 
OR/BR?  Read out the registers directly with the BDI, don't trust nobody.

[snip]

> In the bdi, we executed:
> 
> ATUM>mmh 0xf8000AAA 0x00AA
> ATUM>mmh 0xf8000554 0x0055
> ATUM>mmh 0xf8000AAA 0x0090
> ATUM>mmh 0xf8000AAA 0x0090
> ATUM>mdh 0xf8000000 1
> 
> At which point we got the manufactor id and everything else.
> Unfortunately the next day we weren't able to repeat it - can the
> manufactor id be erased?

Whoo-heee!

No, the manufacture ID cannot be erased.  Something odd is happening.

> Anyways, we were able to write a word:
> 
> ATUM>mmh 0xf8000AAA 0x00AA
> ATUM>mmh 0xf8000554 0x0055
> ATUM>mmh 0xf8000AAA 0x00A0
> ATUM>mmh 0xf8000F00 0xCAFE
> ATUM>mdh 0xf8000F00 1
> 0_f8000f00 : 0xcafe  -13570

Whoo-heee!

> We have yet to be able to repeat that feat at any other address. We
> can read 0xCAFE from 0xf8000F00 , but only after about a minute after
> a bdi boot. We cannot overwrite 0xf8000F00 , nor can we erase the
> entire chip via the documented sequence. As I said we think we have
> timing issues. Any suggestions? More RTFM? We do have a logic
> analyzer.

* Works only after waiting a minute?  That's odd.  Does your flash have 
a reset pin?  Do you have a buffer (address or data) between the 
processor and flash with an enable pin?  Are the reset/enables connected 
properly (not floating)?

* Detune (set to maximum delays) all the speed parameters in the BR/OR 
that controls flash.

* Use the logic analyzer to measure timing (tough nowadays with BGAs and 
fine traces).

gvb