[flashrom] [PATCH] Confirm EN29LV800 bus, timing, and page size

TJ linux at tjworld.net
Sat Feb 6 05:05:30 CET 2010

On Fri, 2010-02-05 at 18:59 -0800, Sean Nelson wrote:
> EN29LV800 is not a JEDEC compatible chip, it uses an odd command 
> sequence like the M29F400BT

Are EON incorrect in the datasheet then, or is there a subtle
distinction between what flashrom means with JEDEC and what EON mean?

The datasheet says:

• JEDEC Standard program and erase commands
• JEDEC standard DATA polling and toggle bits feature

I saw the custom probe functions for EN29F512 and EN29F002A but wasn't
clear that would be needed although I did see they match the datasheet
probe sequence.

I compared the probes to the datasheets because the code questions how
to exit autoselect mode and my reading of it is that it only needs a:

 chip_writeb(0xF0, bios + 0x555); // write address can be any value

since the datasheets say "The system must write the reset command to
exit the autoselect mode and return to reading array data" and the same
for interrupting erase/program modes.

Does it follow that the erase/write operations will also need custom
functions if JEDEC isn't really supported?

I guess I need to get up to speed on JEDEC and the rest of flashrom - I
only came across flashrom last night in pursuit of some clues for
manipulating Phoenix BIOS settings.

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