On Thursday, July 25, 2013 03:34:10 PM Jani Nikula wrote:On Thu, 25 Jul 2013, "Rafael J. Wysocki" <rjw@xxxxxxx> wrote:Yes, it might, but after dropping ACPI_VIDEO_SKIP_BACKLIGHT it should be OK.On Thursday, July 25, 2013 11:09:27 AM Jani Nikula wrote:I didn't claim it didn't work, just that *I* didn't see how it could. ;)On Thu, 25 Jul 2013, "Rafael J. Wysocki" <rjw@xxxxxxx> wrote:Well, if it didn't work, people wouldn't see either improvement or breakageWell, 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
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.
from it, but they do see that, so it evidently works. :-)
Right. I totally missed the call within the ternary operator. Thanks forFirst, the ACPI_VIDEO_SKIP_BACKLIGHT flag seems to be checked beforeAre you sure about that?
it's actually set anywhere.
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
the explanation, and apologies for the noise.
I observe that for the regular non-quirk acpi_video_register() call,Second, with i915 that has opregion support, __acpi_video_register()Actually, that's correct, so we don't need the whole
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.
video_unregister_backlight() thing, calling acpi_video_backlight_quirks() would
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.
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
As to the original problem, and your patch in this thread, what do youI agree, I'm going to send a full revert in a while and we'll think what to
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.
do about all that later.