From 1b7f37e1276bee9043d35a4b39ef2f43d3b2e133 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sat, 17 May 2014 10:48:01 +0200 Subject: ACPI / video: Add an acpi_video_unregister_backlight function Add an acpi_video_unregister_backlight function, which only unregisters the backlight device, and leaves the acpi_notifier in place. Some acpi_vendor driver need this as they don't want the acpi_video# backlight device, but do need the acpi-video driver for hotkey handling. Chances are that this new acpi_video_unregister_backlight() is actually what existing acpi_vendor drivers have wanted all along. Currently acpi_vendor drivers which want to disable the acpi_video# backlight device, make 2 calls: acpi_video_dmi_promote_vendor(); acpi_video_unregister(); The intention here is to make things independent of when acpi_video_register() gets called. As acpi_video_register() will get called on acpi-video load time on non intel gfx machines, while it gets called on i915 load time on intel gfx machines. This leads to the following 2 interesting scenarios: a) intel gfx: 1) acpi-video module gets loaded (as it is a dependency of acpi_vendor and i915) 2) acpi-video does NOT call acpi_video_register() 3) acpi_vendor loads (lets assume it loads before i915), calls acpi_video_dmi_promote_vendor(); which sets ACPI_VIDEO_BACKLIGHT_DMI_VENDOR 4) calls acpi_video_unregister -> not registered, nop 5) i915 loads, calls acpi_video_register 6) acpi_video_register registers the acpi_notifier for the hotkeys, does NOT register a backlight device because of ACPI_VIDEO_BACKLIGHT_DMI_VENDOR b) non intel gfx 1) acpi-video module gets loaded (as it is a dependency acpi_vendor) 2) acpi-video calls acpi_video_register() 3) acpi_video_register registers the acpi_notifier for the hotkeys, and a backlight device 4) acpi_vendor loads, calls acpi_video_dmi_promote_vendor() 5) calls acpi_video_unregister, this unregisters BOTH the acpi_notifier for the hotkeys AND the backlight device So here we have possibly the same acpi_vendor module, making the same calls, but with different results, in one cases acpi-video does handle hotkeys, in the other it does not. Note that the a) scenario turns into b) if we assume the i915 module loads before the vendor_acpi module, so we also have different behavior depending on module loading order! So as said I believe that quite a few existing acpi_vendor modules really always want the behavior of a), hence this patch adds a new acpi_video_unregister_backlight() which gives the behavior of a) independent of module loading order. Signed-off-by: Hans de Goede Signed-off-by: Rafael J. Wysocki --- include/acpi/video.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/acpi/video.h b/include/acpi/video.h index 61109f2609f..ea4c7bbded4 100644 --- a/include/acpi/video.h +++ b/include/acpi/video.h @@ -19,11 +19,13 @@ struct acpi_device; #if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE) extern int acpi_video_register(void); extern void acpi_video_unregister(void); +extern void acpi_video_unregister_backlight(void); extern int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, void **edid); #else static inline int acpi_video_register(void) { return 0; } static inline void acpi_video_unregister(void) { return; } +static inline void acpi_video_unregister_backlight(void) { return; } static inline int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, void **edid) { -- cgit v1.2.3-70-g09d2 From 3cc6919bd61315ea60baf95f3f9868aacfd1ace4 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Wed, 21 May 2014 15:39:54 +0200 Subject: backlight: Add backlight device (un)registration notification Some firmware drivers, ie acpi-video want to get themselves out of the way (in some cases) when their also is a raw backlight device available. Due to module loading ordering being unknown, acpi-video cannot be certain that the backlight_device_registered(BACKLIGHT_RAW) it does for this is the final verdict wrt there being a BACKLIGHT_RAW device. By adding notification acpi-video can listen for backlight devices showing up after it has loaded, and unregister its backlight device if desired. Signed-off-by: Hans de Goede Acked-by: Jingoo Han Signed-off-by: Rafael J. Wysocki --- drivers/video/backlight/backlight.c | 40 +++++++++++++++++++++++++++++++++++++ include/linux/backlight.h | 7 +++++++ 2 files changed, 47 insertions(+) (limited to 'include') diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index bd2172c2d65..428089009cd 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -23,6 +23,7 @@ static struct list_head backlight_dev_list; static struct mutex backlight_dev_list_mutex; +static struct blocking_notifier_head backlight_notifier; static const char *const backlight_types[] = { [BACKLIGHT_RAW] = "raw", @@ -370,6 +371,9 @@ struct backlight_device *backlight_device_register(const char *name, list_add(&new_bd->entry, &backlight_dev_list); mutex_unlock(&backlight_dev_list_mutex); + blocking_notifier_call_chain(&backlight_notifier, + BACKLIGHT_REGISTERED, new_bd); + return new_bd; } EXPORT_SYMBOL(backlight_device_register); @@ -413,6 +417,10 @@ void backlight_device_unregister(struct backlight_device *bd) pmac_backlight = NULL; mutex_unlock(&pmac_backlight_mutex); #endif + + blocking_notifier_call_chain(&backlight_notifier, + BACKLIGHT_UNREGISTERED, bd); + mutex_lock(&bd->ops_lock); bd->ops = NULL; mutex_unlock(&bd->ops_lock); @@ -437,6 +445,36 @@ static int devm_backlight_device_match(struct device *dev, void *res, return *r == data; } +/** + * backlight_register_notifier - get notified of backlight (un)registration + * @nb: notifier block with the notifier to call on backlight (un)registration + * + * @return 0 on success, otherwise a negative error code + * + * Register a notifier to get notified when backlight devices get registered + * or unregistered. + */ +int backlight_register_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&backlight_notifier, nb); +} +EXPORT_SYMBOL(backlight_register_notifier); + +/** + * backlight_unregister_notifier - unregister a backlight notifier + * @nb: notifier block to unregister + * + * @return 0 on success, otherwise a negative error code + * + * Register a notifier to get notified when backlight devices get registered + * or unregistered. + */ +int backlight_unregister_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&backlight_notifier, nb); +} +EXPORT_SYMBOL(backlight_unregister_notifier); + /** * devm_backlight_device_register - resource managed backlight_device_register() * @dev: the device to register @@ -544,6 +582,8 @@ static int __init backlight_class_init(void) backlight_class->pm = &backlight_class_dev_pm_ops; INIT_LIST_HEAD(&backlight_dev_list); mutex_init(&backlight_dev_list_mutex); + BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier); + return 0; } diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 72647429adf..adb14a8616d 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -40,6 +40,11 @@ enum backlight_type { BACKLIGHT_TYPE_MAX, }; +enum backlight_notification { + BACKLIGHT_REGISTERED, + BACKLIGHT_UNREGISTERED, +}; + struct backlight_device; struct fb_info; @@ -133,6 +138,8 @@ extern void devm_backlight_device_unregister(struct device *dev, extern void backlight_force_update(struct backlight_device *bd, enum backlight_update_reason reason); extern bool backlight_device_registered(enum backlight_type type); +extern int backlight_register_notifier(struct notifier_block *nb); +extern int backlight_unregister_notifier(struct notifier_block *nb); #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev) -- cgit v1.2.3-70-g09d2