current powerstate and manually turn on/off?
nate at root.org
Mon Dec 13 12:17:13 PST 2004
M. Warner Losh wrote:
> In message: <41BDF6A7.3040702 at root.org>
> Nate Lawson <nate at root.org> writes:
> : Warner Losh wrote:
> : >>By using sysctl, I do know what's the current powerstate
> : >>of each device. I wounder is there any command or sysctl
> : >>that can manually turn device on or off?
> : >
> : >
> : > Not really, no.
> : I think this is something the drivers should handle and we don't need to
> : add user access to power states since it's probably the biggest way to
> : shoot yourself in the foot. We already power down devices with no
> : driver attached and once drivers get smart about powering down devices
> : that are idle, this would cover all scenarios.
> It would be nice to have a way to say "This is a really strong hint
> that you are now idle, go to lowest power, highest latency to get out
> of it mode."
I believe the driver itself has best knowledge of this, based on
refcount, recent I/O, etc. You don't want the user turning off things
without the driver's knowledge.
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