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

Sean Nelson audiohacked at gmail.com
Sat Feb 6 10:29:36 CET 2010

On 2/5/10 8:05 PM, TJ wrote:
> 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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JEDEC has a 5555/2AAA/5555 command sequence, where as EON uses a 
AAA/555/AAA. Our code is byte based.

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