* [PATCH v2] PM: sleep: Fix runtime PM based cpuidle support
@ 2021-10-29 12:38 Ulf Hansson
2021-11-04 18:46 ` Rafael J. Wysocki
0 siblings, 1 reply; 2+ messages in thread
From: Ulf Hansson @ 2021-10-29 12:38 UTC (permalink / raw)
To: Rafael J . Wysocki, Rafael J . Wysocki, Daniel Lezcano, linux-pm
Cc: Maulik Shah, Anup Patel, Len Brown, Bjorn Andersson, Ulf Hansson,
linux-arm-kernel, linux-riscv, linux-kernel
In the cpuidle-psci case, runtime PM in combination with the generic PM
domain (genpd), may be used when entering/exiting a shared 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
dpm_suspend_late(), the PM core disables runtime PM for all devices. Beyond
this point, calls to pm_runtime_get_sync() to runtime resume a device may
fail and therefore it could also mess up the reference counting in genpd.
To fix this problem, let's call wake_up_all_idle_cpus() in
dpm_suspend_late(), prior to disabling runtime PM. In this way a device
that belongs to a CPU, becomes runtime resumed through cpuidle-psci and
stays like that, because the runtime PM usage count has been bumped in
device_prepare().
Diagnosed-by: Maulik Shah <mkshah@codeaurora.org>
Suggested-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
Changes in v2:
- Moved away from using cpuidle_pause|resume() to solve the problem, but
instead just waking up idle CPUs is suffient, due to other recent merged
changes.
---
drivers/base/power/main.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index ac4dde8fdb8b..2fb08d4f1aca 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1463,6 +1463,7 @@ int dpm_suspend_late(pm_message_t state)
int error = 0;
trace_suspend_resume(TPS("dpm_suspend_late"), state.event, true);
+ wake_up_all_idle_cpus();
mutex_lock(&dpm_list_mtx);
pm_transition = state;
async_error = 0;
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] PM: sleep: Fix runtime PM based cpuidle support
2021-10-29 12:38 [PATCH v2] PM: sleep: Fix runtime PM based cpuidle support Ulf Hansson
@ 2021-11-04 18:46 ` Rafael J. Wysocki
0 siblings, 0 replies; 2+ messages in thread
From: Rafael J. Wysocki @ 2021-11-04 18:46 UTC (permalink / raw)
To: Ulf Hansson
Cc: Rafael J . Wysocki, Rafael J . Wysocki, Daniel Lezcano, Linux PM,
Maulik Shah, Anup Patel, Len Brown, Bjorn Andersson, Linux ARM,
linux-riscv, Linux Kernel Mailing List
On Fri, Oct 29, 2021 at 2:39 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> In the cpuidle-psci case, runtime PM in combination with the generic PM
> domain (genpd), may be used when entering/exiting a shared 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
> dpm_suspend_late(), the PM core disables runtime PM for all devices. Beyond
> this point, calls to pm_runtime_get_sync() to runtime resume a device may
> fail and therefore it could also mess up the reference counting in genpd.
>
> To fix this problem, let's call wake_up_all_idle_cpus() in
> dpm_suspend_late(), prior to disabling runtime PM. In this way a device
> that belongs to a CPU, becomes runtime resumed through cpuidle-psci and
> stays like that, because the runtime PM usage count has been bumped in
> device_prepare().
>
> Diagnosed-by: Maulik Shah <mkshah@codeaurora.org>
> Suggested-by: Rafael J. Wysocki <rafael@kernel.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>
> Changes in v2:
> - Moved away from using cpuidle_pause|resume() to solve the problem, but
> instead just waking up idle CPUs is suffient, due to other recent merged
> changes.
>
> ---
> drivers/base/power/main.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index ac4dde8fdb8b..2fb08d4f1aca 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -1463,6 +1463,7 @@ int dpm_suspend_late(pm_message_t state)
> int error = 0;
>
> trace_suspend_resume(TPS("dpm_suspend_late"), state.event, true);
> + wake_up_all_idle_cpus();
> mutex_lock(&dpm_list_mtx);
> pm_transition = state;
> async_error = 0;
> --
Applied as 5.16-rc material, thanks!
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2021-11-04 18:48 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-10-29 12:38 [PATCH v2] PM: sleep: Fix runtime PM based cpuidle support Ulf Hansson
2021-11-04 18:46 ` Rafael J. Wysocki
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).