SDAA069 August   2025 TDA4VL-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Overview of TDA4VL SoC
    2. 1.2 Purpose of the Document
    3. 1.3 Target Audience and Applications
    4. 1.4 Problem Statement
  5. 2Dynamic Frequency Scaling (DFS) in Linux
    1. 2.1 What is DFS?
    2. 2.2 Linux CPUFREQ Framework
    3. 2.3 Supported CPUFREQ Governors
    4. 2.4 DFS Support Status on TI SoCs
  6. 3Linux Thermal Framework
    1. 3.1 Thermal Zones and Trip Points
    2. 3.2 Cooling Mechanisms: Passive vs Active
    3. 3.3 Role of DFS in Passive Cooling
  7. 4Thermal Support on TDA4VL Devices
    1. 4.1 VTM and Bandgap Sensor Initialization
    2. 4.2 Temperature Monitoring via k3_j7xxx_bandgap Driver
  8. 5Enabling CPU Cooling on TDA4VL
    1. 5.1 Patch to Enable CPU Cooling
    2. 5.2 Testing the Cooling Functionality on TDA4VL
  9. 6Scalability Across TDA4 and Sitara Devices
    1. 6.1 Adapting the Implementation
  10. 7Summary
  11. 8References

3.1 Thermal Zones and Trip Points

A thermal zone represents a temperature-monitored area in the system, such as a CPU cluster, GPU or PMIC. Each thermal zone is associated with:

  • One or more temperature sensors
  • A set of trip points, which are threshold temperatures
  • Associated cooling devices triggered when trip points are reached

Trip points define the action thresholds (for example, passive or active cooling). Trip points can be:

  • Passive: Trigger software based mitigation (for example, reduce CPU frequency)
  • Active: Trigger hardware mechanisms (for example, start or increase fan speed)
  • Critical: Used to shutdown the system to prevent hardware damage

These are typically defined in the device tree and handled through the thermal governor logic within the kernel.