I am using flashrom V1.1 on Darwin and successfully read and wrote the vBIOS of a AMD WX4170 card having the chip listed below.
The read and write log files have been attached.
The graphics card booted in my iMac so I assume that writing the flash succeeded. I am not using the latest development version, it just worked.
flashrom v1.1 on Darwin 19.3.0 (x86_64)
Calibrating delay loop... OK.
Found GigaDevice flash chip "GD25Q40(B)" (512 kB, SPI) on ch341a_spi.
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This flash part has status UNTESTED for operations: PROBE READ ERASE WRITE
The test status of this chip may have been updated in the latest development
version of flashrom. If you are running the latest development version,
work correctly for you with this flash chip. Please include the flashrom log
file for all operations you tested (see the man page for details), and mention
which mainboard or programmer you tested in the subject line.
Thanks for your help!
Reading flash... done.