Re: [Intel-gfx] Linux 3.11-rc2 [backlight] [ASUS N56VZ]

[* SAMÃ *]

When I make acpi_video_backlight_quirks() return false:
- the Fn+x keys are not working anymore (remember that they didn't work 
in 3.10 nor 3.9)
- At least the backlight remains on at boot.
- Gnome brightness settings do not work anymore. Neither do xbacklight.
- Writing to /sys/class/backlight/intel_backlight/brightness works

Regards,
Sam

On 07/29/2013 10:03 PM, Rafael J. Wysocki wrote:
> On Monday, July 29, 2013 09:36:31 PM * SAMÃ * wrote:
> > Hi Rafael,
> >
> >
> > did you commit a full revert?
> Yes, but I left acpi_video_backlight_quirks() (in drivers/acpi/video_detect.c)
> that is used to decide what to do with _DOS.
>
> Can you please check if making that function always return 'false' makes any
> difference?
>
> Rafael
>
>
> > Because I am experiencing quite weird things in rc3.
> > Do we have a bug opened to discuss about it?
> >
> > Here is what I can observe:
> > 1) During boot, probably when loading the driver, backlight gets off (or
> > to a level low enough to make me feel it is off)
> > 2) When I am playing with my Fn+x keys, I am getting a completely full /
> > completely low brightness with no intermediate steps
> > 3) When I am playing with my Fn+x keys while gnome brightness settings
> > panel is open, I am recovering intermediate steps but the Fn+x keys
> > behavior is inverted (the key supposed to lower the brightness make it
> > increase and vice-versa. Note that the gnome brightness indicator also
> > gets inverted).
> > 4) Playing with the mouse on gnome brightness settings is working,
> > except that on the minimum level, backlight gets off
> > 5) Writing to /sys/class/backlight/intel_backlight/brightness works
> >
> >
> > Regards
> >
> > On 07/25/2013 02:57 PM, Rafael J. Wysocki wrote:
> > > On Thursday, July 25, 2013 03:34:10 PM Jani Nikula wrote:
> > > > On Thu, 25 Jul 2013, "Rafael J. Wysocki" <rjw@xxxxxxx> wrote:
> > > > > On Thursday, July 25, 2013 11:09:27 AM Jani Nikula wrote:
> > > > > > On Thu, 25 Jul 2013, "Rafael J. Wysocki" <rjw@xxxxxxx> wrote:
> > > > > > > Well, I wonder what about the appended (untested) patch?
> > > > > > Rafael, before going there, I've been trying to wrap my (poor, rusty
> > > > > > after vacation) head around
> > > > > >
> > > > > > commit 8c5bd7adb2ce47e6aa39d17b2375f69b0c0aa255
> > > > > > Author: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > > > > Date:   Thu Jul 18 02:08:06 2013 +0200
> > > > > >
> > > > > >       ACPI / video / i915: No ACPI backlight if firmware expects Windows 8
> > > > > >
> > > > > > and I can't see how it could work.
> > > > > Well, if it didn't work, people wouldn't see either improvement or breakage
> > > > > from it, but they do see that, so it evidently works. :-)
> > > > I didn't claim it didn't work, just that *I* didn't see how it could. ;)
> > > >
> > > > > > First, the ACPI_VIDEO_SKIP_BACKLIGHT flag seems to be checked before
> > > > > > it's actually set anywhere.
> > > > > Are you sure about that?
> > > > >
> > > > > acpi_video_bus_add() is the .add() callback routine for acpi_video_bus which
> > > > > in fact is an ACPI driver (the naming sucks, but I didn't invent it).  This
> > > > > means that acpi_video_bus_add() can only be called *after* acpi_video_bus
> > > > > has been registered with the ACPI subsystem (and the driver core).  That
> > > > > is done by acpi_bus_register_driver() and, guess what?, this happens in
> > > > > __acpi_video_register().  So clearly, acpi_video_bus_add() *cannot* run before
> > > > > __acpi_video_register().
> > > > Right. I totally missed the call within the ternary operator. Thanks for
> > > > the explanation, and apologies for the noise.
> > > >
> > > > > > Second, with i915 that has opregion support, __acpi_video_register()
> > > > > > should only ever get called once. Which means the acpi_walk_namespace()
> > > > > > with video_unregister_backlight() should never get called in register.
> > > > > >
> > > > > > Please enlighten me.
> > > > > Actually, that's correct, so we don't need the whole
> > > > > video_unregister_backlight() thing, calling acpi_video_backlight_quirks() would
> > > > > be sufficient.
> > > > >
> > > > > Ah, one more reason to do a full revert.  I'm thinking, though, that I'll leave
> > > > > acpi_video_backlight_quirks() as is so that it can be used by
> > > > > acpi_video_bus_(start)|(stop)_devices(), because that doesn't seem to cause
> > > > > problems to happen.
> > > > I observe that for the regular non-quirk acpi_video_register() call,
> > > > acpi_video_backlight_quirks() won't be called during register, but it
> > > > will get called later. This might have subtle effects later on, don't
> > > > you think?
> > > Yes, it might, but after dropping ACPI_VIDEO_SKIP_BACKLIGHT it should be OK.
> > >
> > > > As to the original problem, and your patch in this thread, what do you
> > > > think about having another value in acpi_backlight kernel parameter for
> > > > it? Having an i915 module parameter to tell acpi to use or not use
> > > > quirks seems odd, since the i915 is not really taking over
> > > > anything. It's just passing the info on to acpi.
> > > I agree, I'm going to send a full revert in a while and we'll think what to
> > > do about all that later.
> > >
> > > Thanks,
> > > Rafael

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