Screen Blanking Power Management Requirements

Daniel van Vugt daniel.van.vugt at canonical.com
Tue Jun 25 01:37:37 UTC 2013


I agree. There's not yet been any case I've seen for backlight control 
being part of a display server, _other_ than the problem of device 
permissions.

The regular non-root user does not have permission to write to 
/sys/class/backlight/... so that probably needs to be set up somehow on 
login. Hence it is the display server's problem, a little bit.

Once that's done, the display server should have nothing to do with 
backlight levels. Turning the display on and off (sleeping) should be a 
different operation (which the display server does care about).


On 25/06/13 06:03, Kevin DuBois wrote:
> I added myself for this requirement here (kgunn/robert_ancell, please
> move task if there's a better place):
> https://blueprints.launchpad.net/ubuntu/+spec/client-1303-mir-phone
>
> The approach sounds sensible. The event should come from somewhere else
> to mir.
> There is a caveat though, which is that we are not in a good place (from
> an architectural position) to control the backlight settings when the
> screen turns off. We can pause the mir server and turn the display off
> easily enough, but the backlight control should probably be somewhere else.
>
> Cheers,
> Kevin
>
>
>
>
> On Mon, Jun 24, 2013 at 10:29 AM, Robert Carr <robert.carr at canonical.com
> <mailto:robert.carr at canonical.com>> wrote:
>
>
>
>     Hi! There was a meeting today on power management requirements for
>     Mir on phablet. Sending out an email to capture the new requirements.
>
>     Essentially the model is as follows:
>
>     The shell will use it's event filter, to emit DBus events, i.e.
>     Session Idle (say no input in X minutes), Session Unidle.
>
>     powerd will listen to these events and combine power management
>     policy (i.e. do we blank the screen on idle? perhaps there is a
>     video playing, so we do not at the moment), and in many cases ask
>     the shell again "blank".
>
>     So the requirement on Mir is for methods on mg::Display to
>     blank/unblank the display. Is someone able to take this as a work item?
>
>     Thanks,
>     Robert
>
>
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