Re: [PATCH][ACPI] AC/DC notifier

[Pavel Machek <pavel@ucw.cz>]

On Wed 2009-08-12 01:55:32, Matthew Garrett wrote:
> On Tue, Aug 11, 2009 at 08:51:49PM -0400, Tippett, Matthew wrote:
> 
> >    From a graphics perspective (your area of expertise), this will allow KMS
> >    drivers to do some more intelligent actions based on the ac/dc state. 
> >    Some examples of this could be improving the power consumption of the
> >    graphics hardware through adapting clock memory/engine settings for
> >    reduced power consumption, reducing refresh rate of the display to reduce
> >    scanout memory access, adjusting backlight brightness, etc.
> 
> Right. As you say, my concern is that most of this should belong in 
> userspace. Where we risk hardware damage there's an obvious argument for 
> doing this in kernel, but we should ensure that that's limited to 
> whatever coarse-grain handling is absolutely required rather than doing 
> things like touching display brightness.

Yep... Some may want to save power even when AC is online -- like when
running on UPS. Some may want max performmance even on battery. 
								Pavel 

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