Re: [PATCH 0/8] Suspend block api (version 8)

Bryan Huntsman
2010-06-03T21:50:39Z

>> Yes, having a QoS parameter per-subsystem (or even per-device) is very
>> important for SoCs that have independently controlled powerdomains.
>> If all devices/subsystems in a particular powerdomain have QoS
>> parameters that permit, the power state of that powerdomain can be
>> lowered independently from system-wide power state and power states of
>> other power domains.
>>
> This seems similar to that pm_qos generalization into bus drivers we where
> waving our hands at during the collab summit in April? We never did get
> into meaningful detail at that time.
>
> --mgross

I think there is definitely a need for QoS parameters per-device. I've
been pondering how to incorporate this concept into runtime_pm. One
idea would be to add pm_qos-like callbacks to struct dev_pm_ops, e.g.
runtime_pm_qos_add/update/remove_requirement(). Requirements would be
passed up the tree to the first parent that cares, usually a bus driver.
Is this similar to what you guys were discussing at the collab summit?
Thanks.

- Bryan