Fwd: Brightness on HP EliteBook 8460p

[Pali Rohár]

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.

> > All
> > other values (1-254) are OK (adjust brightness level). When I
> > turn off Ambient Light Sensor (via hp-wmi kernel module) then
> > values 0 and 255 also set brightness level (min and max). My
> > suggestion is to convert value 0 to 1 and 255 to 254 to
> > prevent this problem.
> 
> No idea what's going on here... might be some weird vendor
> magic. The WMI code is rather obscure...
> 
> Luca

ACPI/WMI cannot change brightness, see this what doing that ALS 
function: http://lists.freedesktop.org/archives/dri-devel/2012-
March/020416.html

-- 
Pali Rohár
pali.rohar at gmail.com
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