Hi Dan,

Thanks for your feedback!

I've tested these patches with our platform, but have not tested with any upstream platforms. I added tests for the OS-initiated mode code path in TF-A-Tests [1] that we can run against upstream platforms to verify. I'm not sure how I can get a hold of an upstream platform board; it'd be much appreciated if perhaps maintainers of upstream platforms could help run the tests?

In theory, any platform that supports CPU_SUSPEND would be able to support both platform-coordinated mode and OS-initiated mode, since the power state coordination happens either in the PSCI library implementation or in an HLOS.

Wing

[1] https://review.trustedfirmware.org/c/TF-A/tf-a-tests/+/17684

On Fri, Nov 11, 2022 at 9:43 AM Okash Khawaja okash@google.com wrote:

Hi Dan,

The idea with OSI mode is that HLOS will have more awareness about power sequences and hence will be able to optimise power usage better (e.g. using heuristics) if it had more control. This means having HLOS which contains right modules for a specific platform and specific use case, if we want to do a power/perf comparison between OSI and plat-coordinated modes.

On Fri, Nov 11, 2022 at 5:08 PM Dan Handley via TF-A tf-a@lists.trustedfirmware.org wrote:

...

Hi Wing

Thanks for your contribution. Are there any upstream platforms that

these patches have been tested with? If so, it would be good to have visibility of the sw stack under test. Ideally, there would be at least 1 platform that supported both platform-coordinated mode and OS-initiated mode, so that a fair power/performance comparison can be done.

...

Regards

Dan.

From: Wing Li via TF-A tf-a@lists.trustedfirmware.org Sent: 10 November 2022 05:53 To: tf-a@lists.trustedfirmware.org; tf-a-tests@lists.trustedfirmware.org Subject: [TF-A] PSCI OS-initiated mode

Hi,

The PSCI specification defines two different power state coordination

modes for CPU_SUSPEND that can be used to put a core or a group of cores into a low-power state. These modes are the platform-coordinated mode (default) and the OS-initiated mode (optional). OS-initiated mode is currently not supported by TF-A, while both modes are supported by the Linux Kernel.

...

Requesting reviews for the patches [1] adding support for OS-initiated

mode in TF-A and the corresponding tests in TF-A-Tests. Any feedback and comments are much appreciated.

...

Thanks in advance!

Wing

[1] https://review.trustedfirmware.org/q/topic:psci-osi

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Hi Okash,

On Fri, Nov 11, 2022 at 5:44 PM Okash Khawaja via TF-A < tf-a@lists.trustedfirmware.org> wrote:

Hi Dan,

The idea with OSI mode is that HLOS will have more awareness about power sequences and hence will be able to optimise power usage better (e.g. using heuristics) if it had more control. This means having HLOS which contains right modules for a specific platform and specific use case, if we want to do a power/perf comparison between OSI and plat-coordinated modes.

While that has been the argument for pushing OSI upstream which eventually got merged after 6 years not because we had perf/power comparison data but we got fed up asking for one from the people who were pushing it. They really didn't have the platform implementing both to do the real comparison to be honest.

So are you saying you have done the analysis and have data or just assuming here. If the former, please share the data we have been waiting for nearly 7-8 years now. -- Regards, Sudeep