On Tue, Mar 07, 2023 at 01:05:40PM +0100, Hans de Goede wrote: > 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. ... > + depends on ACPI_VIDEO=n || ACPI_VIDEO I'm wondering if "imply ACPI_VIDEO" (i.o.w. weak dependency) is what suitable here. -- With Best Regards, Andy Shevchenko
