Fwd: Brightness on HP EliteBook 8460p

[Pali Rohár]

On Tuesday 31 July 2012 12:17:05 Alex Deucher wrote:
> On Tue, Jul 31, 2012 at 12:03 PM, Pali Rohár 
<pali.rohar at gmail.com> wrote:
> > On Tuesday 31 July 2012 17:49:32 Luca Tettamanti wrote:
> >> I'm putting back the CC and adding Alex.
> >> 
> >> On Tue, Jul 31, 2012 at 5:07 PM, Pali Rohár
> > 
> > <pali.rohar at gmail.com> wrote:
> >> > Thanks, now working. When I write to acpi video brightness
> >> > file it change brightness and in dmesg is:
> >> > 
> >> > [   47.200998] [drm:radeon_atif_handler], event,
> >> > device_class
> >> > = video, type = 0xd0
> >> > [   47.201102] [drm:radeon_atif_get_sbios_requests], SBIOS
> >> > pending requests: 0x80
> >> > [   47.201104] [drm:radeon_atif_handler], ATIF: 1 pending
> >> > SBIOS requests
> >> > [   47.201105] [drm:radeon_atif_handler], Changing
> >> > brightness
> >> > to 11
> >> 
> >> Great! I'll send an updated patch to Alex soon.
> >> 
> >> > I think that acpi only sent event about brightness key
> >> > pressed, because nothing happened when I pressed it.
> >> > 
> >> > Also for windows is needed special HP application (hp
> >> > hotkey)
> >> > for brightness keys. Without it brightness keys not
> >> > working
> >> > too...
> >> 
> >> I've looked at hp-wmi: the hotkey is indeed dispatched via
> >> WMI
> >> (hp-wmi) so you need something in userspace (KDE, Gnome,
> >> etc)
> >> to respond to that key press.
> > 
> > No, when I rmmod hp-wmi brightness keys still generate
> > events.
> > And when I disable acpi then brightness keys do not generate
> > events but adjust brightness automatically (by BIOS).
> > 
> > I think that hp-wmi on my notebook only handle bluetooth &
> > wifi rfkills and ALS switch. All button working without
> > hp-wmi too.> 
> >> > And there is one problem with
> >> > /sys/class/backlight/radeon_bl.
> >> > When I enable Ambient Light Sensor which auto adjust
> >> > brightness based on sensor data, writing value 0 (min) or
> >> > 255 (max) to /sys/class/backlight/radeon_bl/brightness
> >> > turn
> >> > off display.
> >> 
> >> Ok, that's weird. 0 turns off the panel by design, 255
> >> should
> >> not...
> > 
> > But when ALS is disabled 0 did not turn display off.
> 
> 0 only turns off the backlight, not the panel itself.  Is the
> backlight still partially on or is it just the actual panel
> (timing and image)?
> 
> Alex

I looked at display again and 0 only turn backlight off (or 
adjust minimum value). If I look at display correctly (in dark 
room) I can recognize that display is still on and I can see 
window manager decorations (but text is not readable).

Value 255 when ALS is on has same effect as 0 - adjust minimum 
value (instead maximum).

-- 
Pali Rohár
pali.rohar at gmail.com
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