Re: [RFC/RFT][PATCH v2 3/7] PM / sleep: Make async suspend/resume of devices use device links

[Lukas Wunner]

On Thu, Sep 08, 2016 at 11:28:33PM +0200, Rafael J. Wysocki wrote:
> Make the device suspend/resume part of the core system
> suspend/resume code use device links to ensure that supplier
> and consumer devices will be suspended and resumed in the right
> order in case of async suspend/resume.
> 
> The idea, roughly, is to use dpm_wait() to wait for all consumers
> before a supplier device suspend and to wait for all suppliers
> before a consumer device resume.

For devices with a parent/child relationship, if the child does not
utilize direct_complete, the parent is not allowed to utilize it
either and is runtime resumed upon system sleep.

Don't we need the same for supplier/consumer relationships?

The code enforcing this is in __device_suspend() and looks like this:

	if (parent) {
		spin_lock_irq(&parent->power.lock);

		dev->parent->power.direct_complete = false;
		if (dev->power.wakeup_path
		    && !dev->parent->power.ignore_children)
			dev->parent->power.wakeup_path = true;

		spin_unlock_irq(&parent->power.lock);
	}

I guess we need to iterate over the suppliers here and execute
the block for each of them.

Thanks,

Lukas