The i.MX 8M-Mini can boot from QSPI flash using a dedicated boot image.
The boot config settings are not correctly documented in the EVK Board Hardware User's Guide Rev 0 from 02/2019.
In the document i.MX_Linux_User's_Guide.pdf in the BSP documentation 4.14.98 the settings are correctly given in Table 38
To generate a bootable file for the QSPI with Yocto, you need to include the following setting into local.conf: UBOOT_CONFIG = "fspi" If you don't want/need to make a complete build, just rebuild u-boot: bitbake -c deploy u-boot-imx
Alternatively the file imx-boot-imx8mmevk-fspi.bin-flash_evk_flexspi included already in the BSP demo packages will work as well
Program the image into QSPI: With UUU: uuu-b qspiimx-boot-imx8mmevk-fspi.bin-flash_evk_flexspi With u-boot: