Change in flashrom[master]: ft2232_spi.c - Pack WREN and op in one ftdi_write_data() call to save...

[Simon Buhrow (Code Review)]

Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/flashrom/+/40477

to look at the new patch set (#4).

Change subject: ft2232_spi.c - Pack WREN and op in one ftdi_write_data() call to save programming time
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ft2232_spi.c - Pack WREN and op in one ftdi_write_data() call to save programming time

Every ftdi_write_data() call is quite time consuming as the ftdi-chips seems to take always 2-3ms to respond.
This leads to what the comment already says: Minimize USB transfers by packing as many commands as possible together.

So I packed the WREN command together with the following operation which can be program or erase operation.

This saves about 1 minute when programming a 128MBit Flash with my config!

See timings WREN in extra ftdi_write_data() call:
https://ibb.co/0c1J25d
WREN packed with op:
https://ibb.co/7G1hLkj

I´m using ftdi-2232H chip. That´s why I put it at this place.
If anyone has a good overview about all programmers:
This could be implemented in spi_write_cmd() in case that it is compatible to all programmers
or this principle could be transfered to other programmers which act in a similar way.

Signed-off-by: Simon Buhrow 
Change-Id: Ie4a07499ec5ef0af23818593f45dc427285a9e8a
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M ft2232_spi.c
1 file changed, 19 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/77/40477/4