stop ICE40 FPGA before initializing SPI flash

Since commit bdd0dca (release v1.5.0), ice_fpga_stop() has been called
after the ice_flash_init function, which wakes flash from sleep. In
order to avoid contention on the SPI bus during the flash wake command,
stop the ICE40 FPGA prior to sending SPI flash wake command.

Signed-off-by: Daniel DeGrasse <[email protected]>

src/ice_usb.c

@@ -343,6 +343,9 @@ void dfu_init(uint8_t alt)
         ice_cram_open();
         break;
     case DFU_ALT_FLASH:
+        // Make sure the RP2040 have full access to the SPI bus
+        ice_fpga_stop();
+
         ice_flash_init();
 
         // Ensure reboot in case user doesn't pass -R to dfu-util
@@ -355,9 +358,6 @@ void dfu_init(uint8_t alt)
 
         // Disable all interrupts except USB and DMA (needed for flash program)
         irq_set_mask_enabled(~((1 << USBCTRL_IRQ) | (1 << DMA_IRQ_1)), false);
-
-        // Make sure the RP2040 have full access to the SPI bus
-        ice_fpga_stop();
         break;
     }
 }