Allow only WFI during boot to speed it up

Description

Qcom engineers have been trying to speed up boot time by limiting cpuidle to reach only shallower state (WFI) during boot. After some discussions, it seems like turning the cpuidle-psci driver into loadable kernel module, this can be solved.

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Ulf Hansson December 28, 2023 at 12:43 PM

  • Move the card back to the Open state. Additional work is probably better
    managed within a wider project around boot-time optimizations.

Ulf Hansson October 20, 2023 at 11:47 AM

  • Continue to chat with Daniel about boot-time-optimization and whether how we
    potentially could formalize the work into a project. More discussions will come.

Ulf Hansson October 2, 2023 at 9:55 AM

  • Me and Daniel discussed a solution at Amsterdam. We have a proposal, but
    someone needs to prepare a patch and post it. We will keep discussing this
    at the next Qcom/KWG sync call.

Ulf Hansson August 25, 2023 at 12:10 PM

  • Discussion on how to move forward at the last KWG/Qcom call. Kernel module
    support can't be enforced, we need something else. The typical solution needed
    is that we want the idle states to be disabled during boot and at some point
    later, user space should be able to re-enable them via sysfs.

  • It seems like we need to involve cpuidle maintainers to find the best
    solution.

Ulf Hansson July 4, 2023 at 2:21 PM

  • Continued to discuss this at LKML and at KWG/Qcom call. I have a draft series
    for modularizing cpuidle-psci. It needs some more polishing before I can submit
    it as and RFC. Although, this doesn't cover the complete problem, as we have
    cases where loadable module support can't be used.

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Created June 22, 2023 at 1:13 PM
Updated December 28, 2023 at 12:43 PM