On Fri, 2013-11-22 at 01:08 -0800, Dan Williams wrote:
> From: Lan Tianyu <[email protected]>
>
> Describe the mechanisms for controlling port power policy and
> discovering the port power state.
> + power/pm_qos_no_power_off:
> + This writable flag is a global enable / disable for port
> + power management. Once this file is set to '0' poweroff
> + may occur once all other constraints are met. This
> + defaults to '1'.
> +
> + power/control:
> + This file is writable and can be set to
> + 'auto' (the default) to let the kernel power down the
> + device when it is idle, or 'on' to disable power
> + management and keep the port powered.
These entries contradict one another. I think you need to rewrite
them.
> + connect_type:
> + This writable file reflects the capability of the
> + connection to respond to hotplug events. It returns one
> + of four values 'hotplug', 'hardwired', 'not used', and
> + 'unknown'. The default value is populated by platform
> + firmware, and for all but the 'hardwired' type hotplug
> + support is enabled. One can write 'hardwired' to turn
> + off hotplug (allow the port to power down), or 'hotplug'
> + to keep the port powered. The other types can not be
> + written to the file.
> +
> + Details on the connection type:
> + "hotplug" refers to a port on the outside of a laptop
> + which is visible and connectable.
> +
> + "hardwired" refers to a port that is not visible but
> + connectable. Examples are internal ports for USB
> + bluetooth that can be disconnected via an external
> + switch or a port with a hardwired USB camera.
But those are different cases. The bluetooth module will react to rfkill
with a hotplug. The camera won't. The examples are poorly chosen.
> +
> + "not used" refers to internal port that will never have
> + a device connected to it. These may be empty internal
> + ports, or ports that are not physically
> + exposed on a platform.
> +
> + "unknown" means platform does not provide information
> + for this port.
Regards
Oliver
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