[U-Boot-Users] Where does U-Boot's CFI driver check for top/bottom boot?

Tolunay Orkun listmember at orkun.us
Sun Nov 5 08:56:12 CET 2006

Hi Stefan,

Stefan Roese wrote:
>> I just looked at the datasheet of your flash part as well as datasheet
>> of a couple of intel flash parts as well as the current code. As I
>> suspected for your particular part, it looks like they are using the
>> same values for "Erase Bank Area 1" and "Erase Bank Area 2" irrespective
>> of top boot or bottom boot flash. I think, this is fundamentally wrong
>> and non-compliant with the general CFI standard.
>> I will look at some AMD part datasheets. If this is generally available
>> on all AMD and AMD like parts, we can add it as a patch for AMD only.
>> Otherwise, we will either add CONFIG_GEOMETRY_REVERSED definition or
>> restrict a patch to specific vendor ids (and possibly part ids) which is
>> then a pain to manage.
> I suggest that we also look at the linux mtd cfi driver to see, if and how 
> those devices are handled. I remember seeing something like "broken CFI 
> table" in the linux bootlog on some boards.

I will check MTD CFI driver when I have a bit of free time. I just sent 
an email to the list regarding what I learned from AMD CFI 
specifications. It looks like if we can enumerate those early top/bottom 
devices that use AMD CFI 1.0 specification, we can come up with a patch 
that can handle this case transparently. AMD specification specifies two 
devices. Perhaps we can prepare patch based on these and if there 
happens to be more like these we can expand the list using future patches.


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