Simon Buhrow has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/43282 )
Change subject: ft2232_spi.c: change the chunksize to 280 ......................................................................
Patch Set 2:
The value of 280 is the minimum size needed to realize less ftdi_write_data() calls in patch 40477.
Nevertheless a value of 4096 would be reasonable as well. In fact I can´t see any real need to set chunksize smaller than the default value (here: default equals to max) of the ftdi chunksize which equals to the ftdi buffer size (fix hardware buffer!).
A value of 4096 should result in the same behavior. However 280 is like having (/showing to have) some more control and knowledge about what happens.
I do not prefer any of the options. As there was possibly a reason to set chunksize smaller than the default value I chose 280.