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SubjectRe: [PATCH v3 1/2] PM / sleep: Let devices force direct_complete
Date
Hi Tomeu,

Thank you for the patch.

On Friday 17 April 2015 17:24:49 Tomeu Vizoso wrote:
> Introduce a new per-device flag power.force_direct_complete that will
> instruct the PM core to ignore the runtime PM status of its descendants
> when deciding whether to let this device remain in runtime suspend when
> the system goes into a sleep power state.
>
> 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.

I'll let PM experts comment on the approach, but I believe the new flag would
benefit from being documented (likely in Documentation/power/devices.txt) :-)

> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> ---
> drivers/base/power/main.c | 13 +++++++++----
> include/linux/pm.h | 1 +
> 2 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 3d874ec..728c2dc 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -1438,7 +1438,9 @@ static int __device_suspend(struct device *dev,
> pm_message_t state, bool async) if (parent) {
> spin_lock_irq(&parent->power.lock);
>
> - dev->parent->power.direct_complete = false;
> + if (!dev->parent->power.force_direct_complete)
> + dev->parent->power.direct_complete = false;
> +
> if (dev->power.wakeup_path
> && !dev->parent->power.ignore_children)
> dev->parent->power.wakeup_path = true;
> @@ -1605,9 +1607,12 @@ static int device_prepare(struct device *dev,
> pm_message_t state) * will do the same thing with all of its descendants".
> This only * applies to suspend transitions, however.
> */
> - spin_lock_irq(&dev->power.lock);
> - dev->power.direct_complete = ret > 0 && state.event == PM_EVENT_SUSPEND;
> - spin_unlock_irq(&dev->power.lock);
> + if (state.event == PM_EVENT_SUSPEND) {
> + spin_lock_irq(&dev->power.lock);
> + dev->power.direct_complete = ret > 0 ||
> + dev->power.force_direct_complete;
> + spin_unlock_irq(&dev->power.lock);
> + }
> return 0;
> }
>
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 2d29c64..2e41cfd 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -553,6 +553,7 @@ struct dev_pm_info {
> bool ignore_children:1;
> bool early_init:1; /* Owned by the PM core */
> bool direct_complete:1; /* Owned by the PM core */
> + bool force_direct_complete:1;
> spinlock_t lock;
> #ifdef CONFIG_PM_SLEEP
> struct list_head entry;

--
Regards,

Laurent Pinchart



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