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author | Hans de Goede <hdegoede@redhat.com> | 2022-04-28 17:41:46 +0200 |
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committer | Hans de Goede <hdegoede@redhat.com> | 2022-09-02 09:57:14 +0200 |
commit | 3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4 (patch) | |
tree | b046fbf0214b2962fe207b30d806c418546157cd /drivers/acpi/acpi_video.c | |
parent | ACPI: video: Simplify acpi_video_unregister_backlight() (diff) | |
download | linux-3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4.tar.xz linux-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 'drivers/acpi/acpi_video.c')
-rw-r--r-- | drivers/acpi/acpi_video.c | 50 |
1 files changed, 47 insertions, 3 deletions
diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 8545bf94866f..09dd86f86cf3 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -73,6 +73,16 @@ module_param(device_id_scheme, bool, 0444); static int only_lcd = -1; module_param(only_lcd, int, 0444); +/* + * Display probing is known to take up to 5 seconds, so delay the fallback + * backlight registration by 5 seconds + 3 seconds for some extra margin. + */ +static int register_backlight_delay = 8; +module_param(register_backlight_delay, int, 0444); +MODULE_PARM_DESC(register_backlight_delay, + "Delay in seconds before doing fallback (non GPU driver triggered) " + "backlight registration, set to 0 to disable."); + static bool may_report_brightness_keys; static int register_count; static DEFINE_MUTEX(register_count_mutex); @@ -81,6 +91,9 @@ static LIST_HEAD(video_bus_head); static int acpi_video_bus_add(struct acpi_device *device); static int acpi_video_bus_remove(struct acpi_device *device); static void acpi_video_bus_notify(struct acpi_device *device, u32 event); +static void acpi_video_bus_register_backlight_work(struct work_struct *ignored); +static DECLARE_DELAYED_WORK(video_bus_register_backlight_work, + acpi_video_bus_register_backlight_work); void acpi_video_detect_exit(void); /* @@ -1859,8 +1872,6 @@ static int acpi_video_bus_register_backlight(struct acpi_video_bus *video) if (video->backlight_registered) return 0; - acpi_video_run_bcl_for_osi(video); - if (acpi_video_get_backlight_type() != acpi_backlight_video) return 0; @@ -2086,7 +2097,11 @@ static int acpi_video_bus_add(struct acpi_device *device) list_add_tail(&video->entry, &video_bus_head); mutex_unlock(&video_list_lock); - acpi_video_bus_register_backlight(video); + /* + * The userspace visible backlight_device gets registered separately + * from acpi_video_register_backlight(). + */ + acpi_video_run_bcl_for_osi(video); acpi_video_bus_add_notify_handler(video); return 0; @@ -2125,6 +2140,11 @@ static int acpi_video_bus_remove(struct acpi_device *device) return 0; } +static void acpi_video_bus_register_backlight_work(struct work_struct *ignored) +{ + acpi_video_register_backlight(); +} + static int __init is_i740(struct pci_dev *dev) { if (dev->device == 0x00D1) @@ -2235,6 +2255,18 @@ int acpi_video_register(void) */ register_count = 1; + /* + * acpi_video_bus_add() skips registering the userspace visible + * backlight_device. The intend is for this to be registered by the + * drm/kms driver calling acpi_video_register_backlight() *after* it is + * done setting up its own native backlight device. The delayed work + * ensures that acpi_video_register_backlight() always gets called + * eventually, in case there is no drm/kms driver or it is disabled. + */ + if (register_backlight_delay) + schedule_delayed_work(&video_bus_register_backlight_work, + register_backlight_delay * HZ); + leave: mutex_unlock(®ister_count_mutex); return ret; @@ -2245,6 +2277,7 @@ void acpi_video_unregister(void) { mutex_lock(®ister_count_mutex); if (register_count) { + cancel_delayed_work_sync(&video_bus_register_backlight_work); acpi_bus_unregister_driver(&acpi_video_bus); register_count = 0; may_report_brightness_keys = false; @@ -2253,6 +2286,17 @@ void acpi_video_unregister(void) } EXPORT_SYMBOL(acpi_video_unregister); +void acpi_video_register_backlight(void) +{ + struct acpi_video_bus *video; + + mutex_lock(&video_list_lock); + list_for_each_entry(video, &video_bus_head, entry) + acpi_video_bus_register_backlight(video); + mutex_unlock(&video_list_lock); +} +EXPORT_SYMBOL(acpi_video_register_backlight); + void acpi_video_unregister_backlight(void) { struct acpi_video_bus *video; |