diff options
| author | Hans de Goede <hdegoede@redhat.com> | 2022-12-15 10:41:38 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2022-12-22 17:36:49 +0100 |
| commit | 3cf3b7f012f3ea8bdc56196e367cf07c10424855 (patch) | |
| tree | 28dc75d25e3240b81eab583aa60566b8a6fda3ee /drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | |
| parent | 5aa9d943e9b6bf6e6023645cbe7ce7d5ed84baf4 (diff) | |
ACPI: video: Fix Apple GMUX backlight detection
The apple-gmux driver only binds to old GMUX devices which have an
IORESOURCE_IO resource (using inb()/outb()) rather then memory-mapped
IO (IORESOURCE_MEM).
T2 MacBooks use the new style GMUX devices (with IORESOURCE_MEM access),
so these are not supported by the apple-gmux driver. This is not a problem
since they have working ACPI video backlight support.
But the apple_gmux_present() helper only checks if an ACPI device with
the "APP000B" HID is present, causing acpi_video_get_backlight_type()
to return acpi_backlight_apple_gmux disabling the acpi_video backlight
device.
Add a new apple_gmux_backlight_present() helper which checks that
the "APP000B" device actually is an old GMUX device with an IORESOURCE_IO
resource.
This fixes the acpi_video0 backlight no longer registering on T2 MacBooks.
Note people are working to add support for the new style GMUX to Linux:
https://github.com/kekrby/linux-t2/commits/wip/hybrid-graphics
Once this lands this patch should be reverted so that
acpi_video_get_backlight_type() also prefers the gmux on new style GMUX
MacBooks, but for now this is necessary to avoid regressing backlight
control on T2 Macs.
Fixes: 21245df307cb ("ACPI: video: Add Apple GMUX brightness control detection")
Reported-and-tested-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c')
0 files changed, 0 insertions, 0 deletions