Hi Heiko,
On Fri, Jan 24, 2020 at 2:33 AM Heiko Schocher hs@denx.de wrote:
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?
I was not aware of such problem and not familiar with these details.
I think someone from NXP hardware team would have to take a look and confirm.
Please post these question at the i.MX community forum: https://community.nxp.com/community/imx
Thanks