imx8mp getting too hot

[Marco_Savo]

Hello,

We're using imx8mp in congatec SMARC modules for our embedded board; Wuen we do a stack of these boards, for our implementation, even with a sink the minimal temperature is 70 degrees celsius.

So: in https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/195119/1/AN13054.pdfn-not... is mentioned power gating and clock gating. As I do not have a display, nor audio, nor I use the M7 microcontroller, nor the NPU, nor I need the GPU/DSP etc. how to turn off these devices to avoid the heat they create?

I already asked technical support https://support.nxp.com/s/case/500Tg00000Pm7gmIAB/imx8mp-getting-too-hot but I haven't got a proper answer.

IMX8MPLUS 

[danielchen]

Hi @Marco_Savo 

I would suggest you disable unused peripherals via device tree.  In the Linux tree, you can disable nodes by setting their status to "disable"

&gpu {

    status = "disable";

};

&dsp {

    status = "disable";

};

&npu {

    status = "disable";

};

&cm7 {

    status = "disable";

};

&audio_blk_ctrl {

    status = "disable";

};

Please also refer to imx8mp hardware developer guide. 

use passive heatsinks with thermal interface material

consider active colling (fan) if ambient temperature is high.

optimize PCB layout for heat dissipation

monitor thermal zones via /sys/class/thermal and enable CPU frequency scaling.

Regards

Daniel

[Marco_Savo]

I disabled everything I do not need. I also want to disable the M7. Howto do it? also: ". Users should always configure the CCGR registers to apply proper clock gating. This

is the first and simplest method to reduce wasted energy" howto do this? "Utilize the i.MX 8M Plus power gating controls to reduce the power of hardware blocks not required within the SoC." and this?

[danielchen]

I would suggest you refer to AN13054:  i.MX 8M Plus power consumption measurement.  it illustrates how to measure the current drain of the i.MX 8M Plus, and how to reduce power consumption.

[Marco_Savo]

I quoted the AN13054; I also added the link to it. The document don't specify howto do Power Gating nor Clock Gating

[danielchen]

For the document, you can see i.MX8MP Reference Manual, in Chapter 5, explains power domains, power gating, and low-power modes. 

But  I would suggest create a ticket, send your schematic and layout to NXP for review.

[Marco_Savo]

Hello, no, I have an industrial grade.

I disabled so far:

&flexcan1 {

status = "disabled";

};

&flexcan2 {

status = "disabled";

};

&dsp {

status = "disabled";

};

&pwm1 {

status = "disabled";

};

&pwm2 {

status = "disabled";

};

&pwm4 {

status = "disabled";

};

&aud2htx {

status = "disabled";

};

&irqsteer_hdmi {

status = "disabled";

};

&hdmi_blk_ctrl {

status = "disabled";

};

&hdmi_pavi {

status = "disabled";

};

&hdmi {

status = "disabled";

};

&hdmiphy {

status = "disabled";

};

&lcdif1 {

status = "disabled";

};

&lcdif2 {

status = "disabled";

};

&lcdif3 {

status = "disabled";

};

&ldb {

status = "disabled";

};

&ldb_phy {

status = "disabled";

};

&mipi_dsi {

status = "disabled";

};

&sai2 {

status = "disabled";

};

&sai3 {

status = "disabled";

};

&xcvr {

status = "disabled";

};

&audiomix_pd {

status = "disabled";

};

&sai5 {

status = "disabled";

};

&sai6 {

status = "disabled";

};

&sai7 {

status = "disabled";

};

&easrc {

status = "disabled";

};

&micfil {

status = "disabled";

};

&vpu_g1 {

status = "disabled";

};

&vpu_g2 {

status = "disabled";

};

&vpu_vc8000e {

status = "disabled";

};

&vpu_v4l2 {

status = "disabled";

};

&gpu_3d {

status = "disabled";

};

&gpu_2d {

status = "disabled";

};

&ml_vipsi {

status = "disabled";

};

&mix_gpu_ml {

status = "disabled";

};

&mipi_csi_0 {

status = "disabled";

};

&mipi_csi_1 {

status = "disabled";

};

&cameradev {

status = "disabled";

};

&isi_0 {

status = "disabled";

};

&isi_1 {

status = "disabled";

};

Still, is not enough. Also: I don't see the option to disable the M7 processor. How would you do it? There is some options in the kernel or the uboot to reduce power consumption?