Overtemp_n GPIO question

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
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1

Hi,

There is an GPIO signal Overtemp_n (pin L52) which has NO linux device-tree binding. From devkit schematic, it seems connect to MCU to perform a force shutdown on overheated.

But since there is no device-tree definition for it, is this Overtemp_n managed by Linux? Or is it managed by BPMP? Or something else? And how is it managed?

Regards,

3

hello lunarking1028,

you may enable tegrastats utility to reports memory usage and processor usage for Jetson-based devices. or, there’s another utility, JTop for system monitoring.
both of them are reported from the internal thermal sensors.

please also check developer guide, Thermal Management, for more details.
thanks

4

Hi,

The question is specific about who is driving Overtemp_n pin? L52: TEGRA_MAIN_GPIO(N, 2). I don’t find answer in thermal mgmt page.

  1. NVIDIA linux thermal driver driving Overtemp_n pin? There has to be a device-tree binding for this GPIO pin (otherwise it is not good linux driver programming practice). But I don’t find it.
  2. Some NVIDIA user space software driving this pin? But those software are not open source, so I don’t know whether it is this case or not.
  3. BPMP directly driving Overtemp_n pin?

Thanks.

5

hello lunarking1028,

it should be TEGRA194_MAIN_GPIO(port, offset) for the Jetson Xavier series.
please also check the header file for definition,
$L4T_Sources/r32.5/Linux_for_Tegra/source/public/kernel/nvidia/include/dt-bindings/gpio/tegra194-gpio.h

there’s no device tree definition to use this pin, TEGRA194_MAIN_GPIO(N, 2).
thanks

6

Hi,

Thanks for your reply. Yes, I do mean TEGRA194_MAIN_GPIO. I double checked the pinmux spreadsheet for this pin.
It is pin L52, so TEGRA194_MAIN_GPIO(N, 2).

Then it comes back to my question. Who is controlling this pin in software? Please read my question carefully.

Thanks.

7

hello lunarking1028,

had you check developer guide for the details of Jetson Xavier’s Thermal Management ?
you may review thermal framework architecture.
thanks