We're using an eMMC 4.4.1 chip with our imx.6 design and trying to boot into u-boot using fast-boot mode (BOOT_CFG1=1). This mode works if the eMMC is in a pre-idle state (i.e., just after power-on reset). If the imx.6 is reset without cycling power, the eMMC is NOT in pre-idle and therefore cannot enter fast-boot mode. That's all fine and good, but the imx.6 FRM suggests that if fast-boot mode fails then the eMMC "boots as a normal MMC card from the selected boot partition" (that's a quote from table 8-16 of the FRM). This isn't happening. Instead, the imx.6 locks up and won't boot at all. It's crucial for us that this fail-over behaviour works properly:
Attempt fast-boot -> Fail -> Attempt normal-boot -> Succeed
Attempt fast-boot -> Fail -> Lock up
Am I doing something wrong? If I manually disable fast-boot mode then the boot process works properly, but I'm not seeing that fast-boot fail-over behaviour. We do not have a reset pin connected so it's not feasible to enable the hardware eMMC reset (BOOT_CFG1).
Additional information: Our BOOT_CFG is set to 0x0000DC70