DeviceKit-power and backlight brightness

[David Zeuthen]

Hey,

Sorry for not responding sooner, I mistook this message to only be about
ambient light sensors.

On Thu, 2009-07-02 at 12:33 +0100, Richard Hughes wrote:
> * Do we still need to support backlight devices, even in a XBACKLIGHT world?

No, please revert the patches you just committed.

It's completely wrong to do this as this, for example, will break
multi-monitor setups. You should know very well that it's outside the
scope of DeviceKit-power to do this - instead, I believe, you want to
fix X or whatever display server you are using.

Adding crap like this is just like going back to HAL. There are good
reasons we abandoned that path - too many and too numerous to mention
again.

> * Does the brightness functionality belong in DeviceKit-power or
> something else (DeviceKit-backlight?)

It belongs in the display server, e.g. currently X (and for example
wayland in some version of the future). We've been through this
discussion already when I released the first version of DeviceKit-power,
I don't know why you chose to ignore that large thread.

Having two separate pieces of software (X and devkit-power) pretend that
they control backlight and present different interfaces to, perhaps,
multiple clients, is just a recipe for disaster.

> * Do we want to move the ambient light sensor stuff at the same time?
> * Do we support hardware with more than one backlight device
> (shouldn't, but could happen)

No, you want X to support that. Or wayland. Or whatever daemon you are
using. You don't want some separate daemon like devkit-power to
interfere - it has no business doing this. If you add this to
devkit-power the next thing people are going to add to devkit-power is
to control backlight via other mechanisms (such as monitors with an
auxiliary USB connection).

It's a slippery slope and I, for one, don't like it.

Listen you most probably mean well by adding this feature. You want to
make as many laptops as possible "Just Work"(tm). But that doesn't mean
we should add hacks because X has some deficiencies.. The way to fix
that is, surprise surprise, to fix X - not add hacks.

Please revert this.

     David