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1b7f37e127
Add an acpi_video_unregister_backlight function, which only unregisters
the backlight device, and leaves the acpi_notifier in place. Some acpi_vendor
driver need this as they don't want the acpi_video# backlight device, but do
need the acpi-video driver for hotkey handling.
Chances are that this new acpi_video_unregister_backlight() is actually
what existing acpi_vendor drivers have wanted all along. Currently acpi_vendor
drivers which want to disable the acpi_video# backlight device, make 2 calls:
acpi_video_dmi_promote_vendor();
acpi_video_unregister();
The intention here is to make things independent of when acpi_video_register()
gets called. As acpi_video_register() will get called on acpi-video load time
on non intel gfx machines, while it gets called on i915 load time on intel
gfx machines.
This leads to the following 2 interesting scenarios:
a) intel gfx:
1) acpi-video module gets loaded (as it is a dependency of acpi_vendor
and i915)
2) acpi-video does NOT call acpi_video_register()
3) acpi_vendor loads (lets assume it loads before i915), calls
acpi_video_dmi_promote_vendor(); which sets
ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
4) calls acpi_video_unregister -> not registered, nop
5) i915 loads, calls acpi_video_register
6) acpi_video_register registers the acpi_notifier for the hotkeys,
does NOT register a backlight device because of
ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
b) non intel gfx
1) acpi-video module gets loaded (as it is a dependency acpi_vendor)
2) acpi-video calls acpi_video_register()
3) acpi_video_register registers the acpi_notifier for the hotkeys,
and a backlight device
4) acpi_vendor loads, calls acpi_video_dmi_promote_vendor()
5) calls acpi_video_unregister, this unregisters BOTH the acpi_notifier
for the hotkeys AND the backlight device
So here we have possibly the same acpi_vendor module, making the same calls,
but with different results, in one cases acpi-video does handle hotkeys,
in the other it does not.
Note that the a) scenario turns into b) if we assume the i915 module loads
before the vendor_acpi module, so we also have different behavior depending
on module loading order!
So as said I believe that quite a few existing acpi_vendor modules really
always want the behavior of a), hence this patch adds a new
acpi_video_unregister_backlight() which gives the behavior of a) independent
of module loading order.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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| .. | ||
| platform | ||
| acbuffer.h | ||
| acconfig.h | ||
| acexcep.h | ||
| acnames.h | ||
| acoutput.h | ||
| acpi_bus.h | ||
| acpi_drivers.h | ||
| acpi_io.h | ||
| acpi_numa.h | ||
| acpi.h | ||
| acpiosxf.h | ||
| acpixf.h | ||
| acrestyp.h | ||
| actbl1.h | ||
| actbl2.h | ||
| actbl3.h | ||
| actbl.h | ||
| actypes.h | ||
| apei.h | ||
| button.h | ||
| ghes.h | ||
| hed.h | ||
| pdc_intel.h | ||
| processor.h | ||
| reboot.h | ||
| video.h | ||