Hello Fabio, Peng,
I have here an imx6ull based board from DH electronics [1] which has the IMX_THERMAL driver enabled in U-Boot and Linux. We see on Linux boot random crashes (random means not on every boot, also not even the same crash dump/reason in linux). My first suggestion was instable RMA, but RAM seems stable.
After some investigation it turned out, that setting the REFTOP_SELBIASOFF bit in the linux thermal driver seems the problem.
I saw that the kernel driver does not check first if REFTOP_VBGUP is set and added this, but this did not helped.
U-Boot does this check here: https://gitlab.denx.de/u-boot/u-boot/blob/master/arch/arm/mach-imx/mx6/soc.c...
More investigation into this problem and we found how U-Boot handles this bit:
U-Boot: sets this bit in arch_cpu_init() U-Boot: sets this bit in IMX_THERMAL driver U-Boot: clears this bit in IMX_THERMAL driver
If we now remove the clearing of this bit in U-Boot in the thermal driver, we also see no crashes anymore in Linux (more than 12000 power on/off cycles)
My question is now,
- do you now more about this bit as in the RM is described? Or know somebody we can ask?
- What effect has this bit? May it leads in more power consumption?
- Is it valid to not clear it in U-Boot?
Thanks in advance!
bye, Heiko [1] https://github.com/dh-electronics/u-boot-imx6qdl/blob/dev/2018.05_dhcom/incl...