[coreboot] [PATCH] Raw payload extraction support in cbfstool

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Wed Sep 29 02:02:39 CEST 2010

On 29.09.2010 01:32, Peter Stuge wrote:
> Carl-Daniel Hailfinger wrote:
>>> flashrom takes slighly more time due to various calibration
>>> routines (I could not find a way to disable those, but I didn't
>>> try very hard), 
>> If you already have a known-good delay function with microsecond
>> precision, you could use that instead of waiting for flashrom to
>> calibrate its own delay loop.
> I'd suggest a setting which makes flashrom skip all parallel flash
> chips, to remove any need for calibration.

That would break some Winbond LPC flash chips which require a few
milliseconds of delay between JEDEC toggle reads on erase.
And we also noticed that some SPI chips will react badly (corruption) to
a too tight RDSR instruction schedule.

flashrom on libpayload uses the libpayload-provided delay functions and
skips calibration. Given that LPC/FWH/SPI flash chips usually tolerate
longer than expected delays without problem, you could hook up
programmer_delay to udelay and save a second or so for calibration if
you don't need parallel flash.

> (To be more precise, the deciding factor is whether the chip is on
> the local bus, or if there are some bus master(s) in between, but
> that's generally equivalent to parallel vs. all others.)

Network cards with parallel flash would be classified as "local bus"?



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