diff options
| author |   Hans de Goede <hdegoede@redhat.com> | 2022-04-28 17:41:46 +0200 |
|---|---|---|
| committer | Hans de Goede <hdegoede@redhat.com> | 2022-09-02 09:57:14 +0200 |
| commit | 3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4 (patch) | |
| tree | b046fbf0214b2962fe207b30d806c418546157cd /include/acpi/video.h | |
| parent | ACPI: video: Simplify acpi_video_unregister_backlight() (diff) | |
| download | linux-dev-3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4.tar.xz linux-dev-3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4.zip | |
ACPI: video: Make backlight class device registration a separate step (v2)
On x86/ACPI boards the acpi_video driver will usually initialize before
the kms driver (except i915). This causes /sys/class/backlight/acpi_video0
to show up and then the kms driver registers its own native backlight
device after which the drivers/acpi/video_detect.c code unregisters
the acpi_video0 device (when acpi_video_get_backlight_type()==native).
This means that userspace briefly sees 2 devices and the disappearing of
acpi_video0 after a brief time confuses the systemd backlight level
save/restore code, see e.g.:
https://bbs.archlinux.org/viewtopic.php?id=269920
To fix this make backlight class device registration a separate step
done by a new acpi_video_register_backlight() function. The intend is for
this to be called by the drm/kms driver *after* it is done setting up its
own native backlight device. So that acpi_video_get_backlight_type() knows
if a native backlight will be available or not at acpi_video backlight
registration time, avoiding the add + remove dance.
Note the new acpi_video_register_backlight() function is also called from
a delayed work to ensure that the acpi_video backlight devices does get
registered if necessary even if there is no drm/kms driver or when it is
disabled.
Changes in v2:
- Make register_backlight_delay a module parameter, mainly so that it can
be disabled by Nvidia binary driver users
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Diffstat (limited to 'include/acpi/video.h')
| -rw-r--r-- | include/acpi/video.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/acpi/video.h b/include/acpi/video.h index 4705e339c252..0625806d3bbd 100644 --- a/include/acpi/video.h +++ b/include/acpi/video.h @@ -53,6 +53,7 @@ enum acpi_backlight_type { #if IS_ENABLED(CONFIG_ACPI_VIDEO) extern int acpi_video_register(void); extern void acpi_video_unregister(void); +extern void acpi_video_register_backlight(void); extern int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, void **edid); extern enum acpi_backlight_type acpi_video_get_backlight_type(void); @@ -69,6 +70,7 @@ extern int acpi_video_get_levels(struct acpi_device *device, #else static inline int acpi_video_register(void) { return -ENODEV; } static inline void acpi_video_unregister(void) { return; } +static inline void acpi_video_register_backlight(void) { return; } static inline int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, void **edid) { |