Re: [PATCH 2/2] PM: sleep: Fix runtime PM based cpuidle support

Maulik Shah
2021-10-06T10:28:38Z

Hi,

Thanks for the patch. Looks good to me.

Reviewed-by: Maulik Shah <mkshah@codeaurora.org>

Thanks,
Maulik

On 9/29/2021 8:14 PM, Ulf Hansson wrote:
> In the cpuidle-psci case, runtime PM in combination with the generic PM
> domain (genpd), may be used when entering/exiting an idlestate. More
> precisely, genpd relies on runtime PM to be enabled for the attached device
> (in this case it belongs to a CPU), to properly manage the reference
> counting of its PM domain.
>
> This works fine most of the time, but during system suspend in the
> dpm_suspend_late() phase, the PM core disables runtime PM for all devices.
> Beyond this point and until runtime PM becomes re-enabled in the
> dpm_resume_early() phase, calls to pm_runtime_get|put*() will fail.
>
> To make sure the reference counting in genpd becomes correct, we need to
> prevent cpuidle-psci from using runtime PM when it has been disabled for
> the device. Therefore, let's move the call to cpuidle_pause() from
> dpm_suspend_noirq() to dpm_suspend_late() - and cpuidle_resume() from
> dpm_resume_noirq() into dpm_resume_early().
>
> Diagnosed-by: Maulik Shah <mkshah@codeaurora.org>
> Suggested-by: Maulik Shah <mkshah@codeaurora.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
> drivers/base/power/main.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index cbea78e79f3d..1c753b651272 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -747,8 +747,6 @@ void dpm_resume_noirq(pm_message_t state)
>
> resume_device_irqs();
> device_wakeup_disarm_wake_irqs();
> -
> - cpuidle_resume();
> }
>
> /**
> @@ -870,6 +868,7 @@ void dpm_resume_early(pm_message_t state)
> }
> mutex_unlock(&dpm_list_mtx);
> async_synchronize_full();
> + cpuidle_resume();
> dpm_show_time(starttime, state, 0, "early");
> trace_suspend_resume(TPS("dpm_resume_early"), state.event, false);
> }
> @@ -1336,8 +1335,6 @@ int dpm_suspend_noirq(pm_message_t state)
> {
> int ret;
>
> - cpuidle_pause();
> -
> device_wakeup_arm_wake_irqs();
> suspend_device_irqs();
>
> @@ -1467,6 +1464,7 @@ int dpm_suspend_late(pm_message_t state)
> int error = 0;
>
> trace_suspend_resume(TPS("dpm_suspend_late"), state.event, true);
> + cpuidle_pause();
> mutex_lock(&dpm_list_mtx);
> pm_transition = state;
> async_error = 0;
>

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