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authorHans de Goede <hdegoede@redhat.com>2022-04-28 17:41:46 +0200
committerHans de Goede <hdegoede@redhat.com>2022-09-02 09:57:14 +0200
commit3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4 (patch)
treeb046fbf0214b2962fe207b30d806c418546157cd /drivers/acpi/acpi_video.c
parentACPI: video: Simplify acpi_video_unregister_backlight() (diff)
downloadlinux-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.c50
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(&register_count_mutex);
return ret;
@@ -2245,6 +2277,7 @@ void acpi_video_unregister(void)
{
mutex_lock(&register_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;