Re: [PATCH] PM / sleep: Let devices force direct_complete

From: Kevin Hilman
Date: Fri May 08 2015 - 16:34:00 EST

Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx> writes:

> Introduce a new per-device flag power.force_direct_complete that will
> instruct the PM core to let that device remain in runtime suspend when
> the system goes into a sleep power state, regardless of the PM state of
> any of its descendants.
> This is needed because otherwise it would be needed to get dozens of
> drivers to implement the prepare() callback and be runtime PM active
> even if they don't have a 1-to-1 relationship with a piece of HW.
> This only applies to devices that aren't wakeup-capable, as those would
> need to setup their IRQs as wakeup-capable in their prepare() callbacks.
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> ---
> Hi,
> I'm sending this as a standalone patch as suggested by Alan.
> Thanks,
> Tomeu
> ---
> Documentation/power/runtime_pm.txt | 10 ++++++++++
> drivers/base/power/main.c | 14 ++++++++++----
> include/linux/pm.h | 1 +
> 3 files changed, 21 insertions(+), 4 deletions(-)
> diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
> index 44fe1d2..3b0c68d 100644
> --- a/Documentation/power/runtime_pm.txt
> +++ b/Documentation/power/runtime_pm.txt
> @@ -665,6 +665,16 @@ as appropriate. This only applies to system suspend transitions that are not
> related to hibernation (see Documentation/power/devices.txt for more
> information).
> +For devices that know that can remain runtime suspended when the system

s/that know that/that know they/ ?

> +transitions to a sleep state regardless of the PM state of their descendants,
> +the flag power.force_direct_complete can be set on their device structures.
> +This can be useful when a real device has several virtual devices as
> +descendants and it would be very cumbersome to make sure that they return a
> +positive value in their .prepare() callback and have runtime PM enabled. Usage
> +of power.force_direct_complete is only allowed to devices that aren't
> +wakeup-capable, as they would need to set their IRQs as wakeups in their
> +.prepare() callbacks before the system transitions to a sleep state.

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