topic Re: MX8MN: Thermal driver doesn`t report temperatures below 10 degree celcius in Processor Expert Software

MX8MN: Thermal driver doesn`t report temperatures below 10 degree celcius

MikeEngel — Fri, 20 Nov 2020 10:51:08 GMT

Hi all,

using the Linux kernel 5.4 and the MX8MN we have seen that when temperature drops below 10 degree celius the thermal driver report resource temporarily unavailable.

In the source code of the driver (drivers/thermal/imx8mm_thermal.c) the following code will cause this behavior.

if (tmu->socdata->flags == FLAGS_TMU_VER1) {
val = readl_relaxed(tmu->base + TRITSR) & TRITSR_VAL_MASK;
if (val < TEMP_LOW_LIMIT) {
return -EAGAIN;
}
}

Any explanation why the MX8MN has this low temperature limitation?

Can this limitation be removed for industrial versions of the CPU?

Best regards,

Mike

Re: MX8MN: Thermal driver doesn`t report temperatures below 10 degree celcius

nxf63675 — Wed, 25 Nov 2020 18:07:23 GMT

Hi @MikeEngel ,

Based on IMX8MN Datasheet we have Temperature Sensor Accuracy set to 10-105 (Table 10. Operating ranges).

This is the reason of the limitation and it is applied in industrial products.

Regards,

Israel H.

Re: MX8MN: Thermal driver doesn`t report temperatures below 10 degree celcius

MikeEngel — Thu, 26 Nov 2020 13:47:56 GMT

Thanks for this information. I found the data in the document you mentioned.