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Power Management [clear filter]
Monday, September 23


SAN19-101 Thermal Governors: How to pick the right one
With higher Gigahertz and multiple cores packed in a SoC the need for thermal management for ARM based SoCs gets more and more critical. Thermal governors that define the policy for thermal management play a pivotal role in ensuring thermal safety of the device. Choosing the right one ensures the device performs optimally with in the thermal budget.

In this presentation Keerthy Jagadeesh, Co-maintainer TI BANDGAP AND THERMAL DRIVER explores the behavior of existing governors like step_wise, fair_share, bang_bang governors on A15 based DRA7 SoCs as an example. Governors perform differently based on the Number of Cores the SoC packs, the process node and the use cases. The results on DRA7 family of SoCs will be used to provide guide lines while choosing a particular thermal governor for a given SoC based on the above mentioned parameters.

avatar for Keerthy Jagadeesh

Keerthy Jagadeesh

Software Engineer, Texas Instruments
Keerthy Jagadeesh is part of Linux core product development team of the Texas Intruments and has been an active linux contibutor for the past 8+ years. He has worked mainly on thermal management for TI SoCs, PMIC driver development, Implementing low power modes for AM437x SoCs. Currently... Read More →

Monday September 23, 2019 2:00pm - 2:25pm
Sunset IV (Session 2)


SAN19-117 An Overview of the opensource Arm System Control Processor (SCP) Firmware Architecture
The Arm SCP-Firmware provides a reference firmware implementation for the System Control Processor (SCP) and Manageability Control Processor (MCP) components found in several Arm Compute Sub-Systems. It provides Power Management and System Control functionality that is compliant with the Arm System Control and Management Interface (SCMI). The SCP-Firmware is based on a modular design which caters to multiple deployment models. The SCP Firmware lends itself to easy deployment, whether RTOS or bare metal. It is based on a core Framework which provides common services to all modules. The Modules plug into the framework and implement functionalities which can be chosen on a per-platform basis. This provides complete flexibility for any platform or implementation to provide their own modules and ‘special implementations’ as required. Additionally, the SCP Firmware abstracts Execution Context requirements enabling it to be deployed in a wide variety on systems and architectures and even run on host environments.

In my presentation, I will talk about how the SCP firmware positions itself in Power management paradigms based on the division of responsibilities between the OS kernel and the firmware. We will briefly go through the Framework and Module design and how they provide flexibility to a platform to enable fast deployment. We will also talk about the way the various firmware components communicate with each other using events and notifications, which can be well abstracted from the underlying execution context. The advantages that the SCP firmware provides due to its lightweight and flexible scheduling model which can scale from single-threaded to multi-threaded will be discussed. Finally, we will discuss the guidelines for developing code based on the opensource SCP-Firmware and the benefits of doing so.

avatar for Souvik Chakravarty

Souvik Chakravarty

Staff Software Engineer, ARM Limited
Souvik is a Staff Software Engineer in the Architecture and Technology Group at Arm, where his primary areas of focus are System and Power Management software standards and specifications.

Monday September 23, 2019 4:00pm - 4:50pm
Pacific Room (Keynote)
Tuesday, September 24


SAN19-213 A Guide to enabling new Power Management & System Control Models via Arm SCMIv2.0
Continuing from Linaro Connect BKK19, where the Arm SCMI Roadmap was unveiled, we have released SCMI specification version 2.0 in July/August 2019. This version of the specification enables new usage models to cater to Power Management and System Control requirements in Mobile, Embedded and Automotive markets.

Cost sensitive SoC designs may not opt for a stand-alone microcontroller for System Control. For such systems, SCMIv2.0 enables the System Control Firmware to be resident in the secure world. We shall go over the requirements to implement the kernel and firmware code for such systems to comply with SCMI.

SCMIv2.0 introduces the concept of Per-Agent Resource Isolation Domains. Many SoCs today implement multiple PE Clusters where each cluster runs a different OS instance. Such systems require the SoC resources to be partitioned dynamically among the various agents (we may model each such cluster to be a SCMI agent). SCMIv2.0 introduces new commands to achieve this. In our session, we shall talk about how this can be done using the new SCMIv2.0 commands, and the agent-id and transport requirements and semantics for such a model to work. We will also provide an overview how such a model might work for Virtualized Systems. The presentation will cover how newly introduced Power Domain pre-notifications can be used for co-operative Power Management according to user defined policies in such systems.

SCMIv2.0 introduces FastChannels. We will provide an overview of its requirements and how FastChannels can be enabled for latency critical operations. We will also touch upon the Reset Management Protocol which can be used for device resets. Finally we will walk-through the features planned to be introduced in the next version of SCMI.

avatar for Souvik Chakravarty

Souvik Chakravarty

Staff Software Engineer, ARM Limited
Souvik is a Staff Software Engineer in the Architecture and Technology Group at Arm, where his primary areas of focus are System and Power Management software standards and specifications.

Tuesday September 24, 2019 12:00pm - 12:50pm
Sunset V (Session 1)