[flashrom] performance of flashrom (with FT2232H)

[Amelkin, Aleksandr]

I noticed that it takes painfully long for flashrom to even simply read a 16MB flash chip
using FT2232H (Olimex ARM-USB-TINY-H) programmer.

The time it takes would be appropriate for kHz-range SPI clocks, not for 30MHz SPI clock
that FT2232H provides.

I checked with an oscilloscope and found out that there are long multi-millisecond delays between short (~150us) SPI clock bursts during simple chip read operation ('-r' or 'reading old flash chip contents'). The delays are 2ms for native Windows 7 64-bit on an Intel Core-i7 2600 @ 3.4GHz, or as long as 7ms for a Ubuntu Linux running in a virtual box on the same Windows machine.

I didn't look any deeper though.

Has anyone done any profiling or have any ideas as to what may be causing this behavior?

With best regards,
Alexander Amelkin.
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