[Bug 73252] [Baytrail-M] brightness can't be adjusted: no ASLE interrupt code

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=73252

--- Comment #21 from Aaron Lu <aaron.lu at intel.com> ---
(In reply to comment #18)
> (In reply to comment #17)
> > Created attachment 99939 [details]
> > dmesg with drm.debug=0xe and removed loglevel=0
> 
> I don't see drm.debug=0xe nor debug messages.
> 
> > when press the brightness hotkey, it shows ideapad_laptop: Unkown event：15
> 
> That's a problem, and one I can't help with.
> 
> > ls /sys/class/backlight
> > > acpi_video0  intel_backlight
> > 
> > echo value to acpi_video0/brightness, brightness no change.(this is used for
> > OS.)
> 
> This is another problem. Aaron (CC), how does the asle irq get triggered?
> Can you debug this part please?

By firmware ASL code to write 1 to the PCI ASLE register(0xe4) I suppose, which
is done after firmware has set some appropriate value in some operation region
registers(so that the i915 irq handler knows what service the firmware has
requested). The problem is, firmware may not use operation region to control
backlight in this system(acpidump should tell us this) and if i915 irq will
handle that or not(I don't know much about this).

Another problem for this system is that if it could receive any event on
backlight hotkey press, the 'Unknown event: 15' looks problematic and should be
taken care by the platform driver ideapad_laptop or udev's keymapping.

Eva, if you run acpi_listen on cmdline and then press the backlight hotkey, did
you see any output?

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