SPRACL7 March   2019 AM5746 , AM5748 , AM5749

 

  1.   AM574x thermal considerations
    1.     Trademarks
    2. 1 Overview
    3. 2 Important Notes
    4. 3 Test Overview
      1. 3.1 OS Idle
      2. 3.2 Dhrystone
      3. 3.3 Temperature Measurement
      4. 3.4 OPP Definitions
    5. 4 Data and Results
      1. 4.1 OPP Settings and Linux Thermal Framework
      2. 4.2 Power and Thermal Chamber Measurements
      3. 4.3 OS Idle at OPP_NOM
      4. 4.4 Dhrystone 1 Core at OPP_NOM
      5. 4.5 Dhrystone 2 Core at OPP_NOM
      6. 4.6 Dhrystone 1 Core at OPP_HIGH
      7. 4.7 Dhrystone 2 Core at OPP_HIGH
    6. 5 References

4.1 OPP Settings and Linux Thermal Framework

Tests are conducted with Processor SDK 04.02.00 at following OPP levels:

Default OPP Levels
MPU GPU DSP IVA
NOM HIGH HIGH HIGH

The MPU domain OPP defaults to NOM when idle and increases to HIGH when under load. OPP levels for DSP and IVA cores can be changed but that must be done by editing the U-Boot defconfig file with the desired OPP level and recompiling.

Applicable to the AM574x, the Linux kernel on this device uses the CPUFreq driver to support multiple OPPs for the MPU domain and dynamically changes between them. As such, a desired maximum frequency must be set if you are seeking power consumption at a frequency lower than the maximum.

Additionally, the Linux thermal framework needs to be disabled, otherwise, the maximum frequency is reduced as the MPU heats up to prevent thermal shutdown. This must only be done for data gathering purposes when the junction temperature exceeds the levels defined in the device tree and is not recommended for a production system.