mirror-linux/include
Hans de Goede 3608a2cd81 backlight: apple_bl: Use acpi_video_get_backlight_type()
On some MacBooks both the apple_bl and the apple-gmux backlight drivers
may be able to export a /sys/class/backlight device.

To avoid having 2 backlight devices for one LCD panel until now
the apple-gmux driver has been calling apple_bl_unregister() to move
the apple_bl backlight device out of the way when it loads.

Similar problems exist on other x86 laptops and all backlight drivers
which may be used on x86 laptops have moved to using
acpi_video_get_backlight_type() to determine whether they should load
or not.

Switch apple_bl to this model too, so that it is consistent with all
the other x86 backlight drivers.

Besides code-simplification and consistency this has 2 other benefits:

1) It removes a race during boot where userspace will briefly see
   an apple_bl backlight and then have it disappear again, leading to e.g.:
   https://bbs.archlinux.org/viewtopic.php?id=269920

2) This allows user to switch between the drivers by passing
   acpi_backlight=apple_gmux or acpi_backlight=vendor on the kernel
   commandline.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230307120540.389920-1-hdegoede@redhat.com
2023-03-16 13:33:11 +01:00
..
acpi Remove Intel compiler support 2023-03-05 10:49:37 -08:00
asm-generic Driver core changes for 6.3-rc1 2023-02-24 12:58:55 -08:00
clocksource
crypto
drm Driver core changes for 6.3-rc1 2023-02-24 12:58:55 -08:00
dt-bindings ARM: SoC drivers for 6.3 2023-02-27 10:04:49 -08:00
keys
kunit
kvm
linux backlight: apple_bl: Use acpi_video_get_backlight_type() 2023-03-16 13:33:11 +01:00
math-emu
media media updates for v6.3-rc1 2023-02-26 11:47:26 -08:00
memory
misc
net sctp: add a refcnt in sctp_stream_priorities to avoid a nested loop 2023-02-23 12:59:40 -08:00
pcmcia
ras
rdma
rv
scsi SCSI misc on 20230303 2023-03-03 14:41:50 -08:00
soc
sound sound fixes for 6.3-rc1 2023-03-04 10:53:59 -08:00
target
trace f2fs-for-6.3-rc1 2023-02-27 16:18:51 -08:00
uapi SCSI misc on 20230303 2023-03-03 14:41:50 -08:00
ufs SCSI misc on 20230303 2023-03-03 14:41:50 -08:00
vdso
video
xen Driver core changes for 6.3-rc1 2023-02-24 12:58:55 -08:00