Re: [Regression]: Changing brightness does not work with v3.16-rc4

[Julian Wollrath <jwollrath@web.de>]

Am Wed, 16 Jul 2014 10:35:33 +0200
schrieb Hans de Goede <hdegoede@redhat.com>:

> Hi,
> 
> On 07/16/2014 10:13 AM, Hans de Goede wrote:
> 
> <snip>
> 
> > I realize that this does not fix Julian's problem. As I see it
> > there are 2 separate problems here:
> > 
> > 1) backlight control issues on Windows 8 laptops, this is what we
> > are trying to solve with video.use_native_backlight=1 (and without
> > using any acpi_osi override)
> > 
> > 2) Some component in the stack needs to responds to backlight
> > key-presses and actually use the backlight control to change the
> > backlight setting, normally this is done by gnome / kde / unity /
> > xfce, but what about users not running those? For some of those
> > users brightness_switch_enabled=1 has been making things work for
> > them, but that only works if acpi-video controls the backlight,
> > which it does not do everywhere, and which we want to get away from
> > for Windows 8 laptops since it is just too broken there.
> > 
> > Note that 2. is not limited to Windows 8 laptops / acpi-video in any
> > way, we've 23 non acpi-video backlight drivers under
> > drivers/platform/x86/ alone + the native gpu backlight drivers. So
> > what we really need is a solution for any laptop not using
> > acpi-video for backlight control and not running one of the big 4
> > desktop environments.
> > 
> > Note that we pretty much have the same problem for any acpi event,
> > power button pressed, lid closed, etc. are all "key press" type
> > events typically handles by the desktop enviroment (e.g. we don't
> > automatically suspend on lid-close, we just tell userspace). And we
> > already have a solution for these type of events when running a
> > desktop environment which handles them, these get handled by acpid.
> > So to me it seems that
> 
> s/handles/does not handle/  small but important typo.
> 
> > the obvious (and one and only right) way to fix this is to teach
> > acpid to deal with brightness key-presses.
> > 
> > I'm willing to write a patch for acpid to implement this, and then
> > Julian's setup should just work without needing any special kernel
> > commandline options.
> > 
> > Julian would that be an acceptable solution for you, and would you
> > be willing to test such a patch ?
Yes, of course that would be an acceptable solution for me and yes, I
would be willing to test such a patch.

Cheers,
Julian