Re: [PATCH v5 1/2] PM / sleep: Go direct_complete if driver has no callbacks
From: Alan Stern
Date: Tue Sep 29 2015 - 10:39:39 EST
On Tue, 29 Sep 2015, Tomeu Vizoso wrote:
> If a suitable prepare callback cannot be found for a given device and
> its driver has no PM callbacks at all, assume that it can go direct to
> complete when the system goes to sleep.
> The reason for this is that there's lots of devices in a system that do
> no PM at all and there's no reason for them to prevent their ancestors
> to do direct_complete if they can support it.
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> +void device_check_pm_callbacks(struct device *dev)
> + dev->power.no_pm_callbacks =
> + (!dev->bus || pm_ops_is_empty(dev->bus->pm)) &&
> + (!dev->class || pm_ops_is_empty(dev->class->pm)) &&
> + (!dev->type || pm_ops_is_empty(dev->type->pm)) &&
> + (!dev->pm_domain || pm_ops_is_empty(&dev->pm_domain->ops)) &&
> + (!dev->driver || pm_ops_is_empty(dev->driver->pm));
One fairly minor point: You should lock dev->power.lock before setting
this bitfield. This is because bitfields are not SMP-safe.
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