[U-Boot-Users] AMD29LV800T in 16bit mode x4 devices (64bit bus)

[Richard Danter]

Wolfgang Denk wrote:
> In message <42D2DC59.6090507 at ntlworld.com> you wrote:
> 
>>Is there a driver that supports this flash within U-Boot? I can't see 
>>one, but want to make sure I didn't miss it before I reinvent the wheel!

> 
> There are several. First, there is the general CFI driver,  and  then
> there are several board specific drivers like board/tqm8260/flash.c

I have tried both of the suggested drivers with neither working for me.

I have spent more time looking at the tqm8260/flash.c and have managed 
to make some improvements. Initially it was unable to even read back the 
device type but I noticed that if I single stepped (using JTAG) the 
flash_get_size() function then it _was_ able to correctly read the 
device type.

This sounded like a timing issue until someone suggested that between 
the writes and reads I should have "sync" and/or "eieio" to ensure the 
CPU (MPC7400) does not execute them out of sequence. This certainly 
fixed the flash_get_size() function, but I am still unable to write to 
the flash (eg using saveenv). Though again I do see some data written if 
I am single-stepping the write_dword() function.

Reading data from the flash works just fine.

Any suggestions?

Thanks
Rich