[U-Boot-Users] CFI flash polling for AMD/SPANSION?

[Wolfgang Denk]

In message <9CAC8A3B-89FA-44C3-B554-A53C79A0003D at kernel.crashing.org> you wrote:
> 
> I'm told that higher frequencies we have issues using the toggle  
> method on 85xx/86xx parts from freescale.  But use DQ7 at those freq  

Given the fact that the CFI code has absolutely no knowledge about
which processor it is running on, this means one or both of two
things:

1) There are issues with certain versions of certain toolchains which
   happen to be used with the processors in question

2) The processors in question are more likely to have problems with
   unexpected out-of-order scheduling / instruction reordering etc.

Please note that the current CFI driver accesses the flash by plain
pointer references, in some cases even without using "volatile". This
is supposed to cause problems sooner or later. 

I think the CFI driver needs some basic  rework  to  get  ridof  such
pointer  accesses and use proper accessor functions/macros instead to
make sure we have all the memory barriers etc. we may need.

> seems to work reliable for the flash parts we have on some of the  
> boards.

If the DQ7 method works better, we could compare the code. Check  for
example  for  missing volatiles - but even better fix the code to use
correct accessors.

> It looks like it just uses DQ6/toggle if I'm reading the code correctly.

Note that Linux calls a (map)->write() function to access the flash.


Best regards,

Wolfgang Denk

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