Hello Arai san,
I understand the customer requirement as pointed by you.
I verified this on the FX3S FPGA DVK by PACTRON and since there was some image in the FLASH already, i had to change the PMODE to USB first to make it enumerate and then change it back to PMODE: 0Z1.
In customer's use case, during first boot up, the device will "fail" loading of the image from FLASH into RAM since the FLASH will be empty or won't have the first 2 bytes as 'CY' and will fallback to USB boot and enumerate as Cypress USB Bootloader Device.
Once the device enumerates as Cypress USB Bootloader Device, you can program the SPI FLASH using the control center and once it succeeded, reboot (or power cycle) the device.
The device will again try to load the data from FLASH to RAM and since the image has CY initials as the first 2 bytes, the device will successfully enumerate as the customer's firmware device (Cypress Bulkloop Example Device, in my case).
Once the device enumerates as the expected device, the customer can use the above implementation when they want to program the device again, to make the enumeration fallback to USB.
Regards,
Yashwant
