From 7e3711eb87c584ed224a7ad7000eba36e6fa3a51 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Fri, 21 Mar 2025 10:53:55 +0100 Subject: fbdev: Track display blanking state Store the display's blank status in struct fb_info.blank and track it in fb_blank(). As an extra, the status is now available from the sysfs blank attribute. Support for blanking is optional. Therefore framebuffer_alloc() initializes the state to FB_BLANK_UNBLANK (i.e., the display is on). If the fb_blank callback has been set, register_framebuffer() sets the state to FB_BLANK_POWERDOWN. On the first modeset, the call to fb_blank() will update it to _UNBLANK. This is important, as listeners to FB_EVENT_BLANK will now see the display being switched on. Signed-off-by: Thomas Zimmermann Acked-by: Simona Vetter Link: https://lore.kernel.org/r/20250321095517.313713-3-tzimmermann@suse.de Signed-off-by: Lee Jones --- include/linux/fb.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/fb.h b/include/linux/fb.h index cd653862ab99..348aa2e146e2 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -472,6 +472,8 @@ struct fb_info { struct list_head modelist; /* mode list */ struct fb_videomode *mode; /* current mode */ + int blank; /* current blanking; see FB_BLANK_ constants */ + #if IS_ENABLED(CONFIG_FB_BACKLIGHT) /* assigned backlight device */ /* set before framebuffer registration, -- cgit v1.2.3-59-g8ed1b From 726491f2038ec71122d45700f3abf36fdb277aaa Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Fri, 21 Mar 2025 10:53:57 +0100 Subject: backlight: Implement fbdev tracking with blank state from event Look at the blank state provided by FB_EVENT_BLANK to determine whether to enable or disable a backlight. Remove the tracking fields from struct backlight_device. Tracking requires three variables, fb_on, prev_fb_on and the backlight's use_count. If fb_on is true, the display has been unblanked. The backlight needs to be enabled if the display was blanked before (i.e., prev_fb_on is false) or if use_count is still at 0. If fb_on is false, the display has been blanked. In this case, the backlight has to be disabled was unblanked before and the backlight's use_count is greater than 0. This change removes fbdev state tracking from blacklight. All the backlight requires it its own use counter and information about changes to the display. Removing fbdev internals makes backlight drivers easier to integrate into other display drivers, such as DRM. Signed-off-by: Thomas Zimmermann Reviewed-by: "Daniel Thompson (RISCstar)" Acked-by: Simona Vetter Link: https://lore.kernel.org/r/20250321095517.313713-5-tzimmermann@suse.de Signed-off-by: Lee Jones --- drivers/video/backlight/backlight.c | 14 +++++++------- include/linux/backlight.h | 10 +--------- 2 files changed, 8 insertions(+), 16 deletions(-) (limited to 'include') diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index f699e5827ccb..bb01f57c4683 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -98,9 +98,9 @@ static int fb_notifier_callback(struct notifier_block *self, struct backlight_device *bd; struct fb_event *evdata = data; struct fb_info *info = evdata->info; + const int *fb_blank = evdata->data; struct backlight_device *fb_bd = fb_bl_device(info); - int node = info->node; - int fb_blank = 0; + bool fb_on, prev_fb_on; /* If we aren't interested in this event, skip it immediately ... */ if (event != FB_EVENT_BLANK) @@ -116,15 +116,15 @@ static int fb_notifier_callback(struct notifier_block *self, if (fb_bd && fb_bd != bd) goto out; - fb_blank = *(int *)evdata->data; - if (fb_blank == FB_BLANK_UNBLANK && !bd->fb_bl_on[node]) { - bd->fb_bl_on[node] = true; + fb_on = fb_blank[0] == FB_BLANK_UNBLANK; + prev_fb_on = fb_blank[1] == FB_BLANK_UNBLANK; + + if (fb_on && (!prev_fb_on || !bd->use_count)) { if (!bd->use_count++) { bd->props.state &= ~BL_CORE_FBBLANK; backlight_update_status(bd); } - } else if (fb_blank != FB_BLANK_UNBLANK && bd->fb_bl_on[node]) { - bd->fb_bl_on[node] = false; + } else if (!fb_on && prev_fb_on && bd->use_count) { if (!(--bd->use_count)) { bd->props.state |= BL_CORE_FBBLANK; backlight_update_status(bd); diff --git a/include/linux/backlight.h b/include/linux/backlight.h index f5652e5a9060..03723a5478f8 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -294,15 +294,7 @@ struct backlight_device { struct device dev; /** - * @fb_bl_on: The state of individual fbdev's. - * - * Multiple fbdev's may share one backlight device. The fb_bl_on - * records the state of the individual fbdev. - */ - bool fb_bl_on[FB_MAX]; - - /** - * @use_count: The number of uses of fb_bl_on. + * @use_count: The number of unblanked displays. */ int use_count; }; -- cgit v1.2.3-59-g8ed1b From b01beb2f1f6bcda17634a5b529865ffc5a9b795f Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Fri, 21 Mar 2025 10:53:59 +0100 Subject: backlight: Replace fb events with a dedicated function call Remove support for fb events from backlight subsystem. Provide the helper backlight_notify_blank_all() instead. Also export the existing helper backlight_notify_blank() to update a single backlight device. In fbdev, call either helper to inform the backlight subsystem of changes to a display's blank state. If the framebuffer device has a specific backlight, only update this one; otherwise update all. v4: - protect blacklight declarations with IS_REACHABLE() (kernel test robot) v3: - declare empty fb_bl_notify_blank() as static inline (kernel test robot) Signed-off-by: Thomas Zimmermann Acked-by: Simona Vetter Reviewed-by: "Daniel Thompson (RISCstar)" Link: https://lore.kernel.org/r/20250321095517.313713-7-tzimmermann@suse.de Signed-off-by: Lee Jones --- drivers/video/backlight/backlight.c | 85 +++++---------------------------- drivers/video/fbdev/core/fb_backlight.c | 12 +++++ drivers/video/fbdev/core/fbmem.c | 2 + include/linux/backlight.h | 22 ++++++--- include/linux/fb.h | 4 ++ 5 files changed, 46 insertions(+), 79 deletions(-) (limited to 'include') diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 1c43f579396f..9dc93c5e480b 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -15,7 +15,6 @@ #include #include #include -#include #include #ifdef CONFIG_PMAC_BACKLIGHT @@ -57,10 +56,10 @@ * a hot-key to adjust backlight, the driver must notify the backlight * core that brightness has changed using backlight_force_update(). * - * The backlight driver core receives notifications from fbdev and - * if the event is FB_EVENT_BLANK and if the value of blank, from the - * FBIOBLANK ioctrl, results in a change in the backlight state the - * update_status() operation is called. + * Display drives can control the backlight device's status using + * backlight_notify_blank() and backlight_notify_blank_all(). If this + * results in a change in the backlight state the functions call the + * update_status() operation. */ static struct list_head backlight_dev_list; @@ -78,11 +77,8 @@ static const char *const backlight_scale_types[] = { [BACKLIGHT_SCALE_NON_LINEAR] = "non-linear", }; -#if defined(CONFIG_FB_CORE) || (defined(CONFIG_FB_CORE_MODULE) && \ - defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)) -static void backlight_notify_blank(struct backlight_device *bd, - struct device *display_dev, - bool fb_on, bool prev_fb_on) +void backlight_notify_blank(struct backlight_device *bd, struct device *display_dev, + bool fb_on, bool prev_fb_on) { guard(mutex)(&bd->ops_lock); @@ -103,68 +99,18 @@ static void backlight_notify_blank(struct backlight_device *bd, } } } +EXPORT_SYMBOL(backlight_notify_blank); -/* - * fb_notifier_callback - * - * This callback gets called when something important happens inside a - * framebuffer driver. The backlight core only cares about FB_BLANK_UNBLANK - * which is reported to the driver using backlight_update_status() - * as a state change. - * - * There may be several fbdev's connected to the backlight device, - * in which case they are kept track of. A state change is only reported - * if there is a change in backlight for the specified fbdev. - */ -static int fb_notifier_callback(struct notifier_block *self, - unsigned long event, void *data) +void backlight_notify_blank_all(struct device *display_dev, bool fb_on, bool prev_fb_on) { struct backlight_device *bd; - struct fb_event *evdata = data; - struct fb_info *info = evdata->info; - const int *fb_blank = evdata->data; - struct backlight_device *fb_bd = fb_bl_device(info); - bool fb_on, prev_fb_on; - - /* If we aren't interested in this event, skip it immediately ... */ - if (event != FB_EVENT_BLANK) - return 0; - - bd = container_of(self, struct backlight_device, fb_notif); - - if (fb_bd && fb_bd != bd) - return 0; - - fb_on = fb_blank[0] == FB_BLANK_UNBLANK; - prev_fb_on = fb_blank[1] == FB_BLANK_UNBLANK; - - backlight_notify_blank(bd, info->device, fb_on, prev_fb_on); - - return 0; -} - -static int backlight_register_fb(struct backlight_device *bd) -{ - memset(&bd->fb_notif, 0, sizeof(bd->fb_notif)); - bd->fb_notif.notifier_call = fb_notifier_callback; - return fb_register_client(&bd->fb_notif); -} + guard(mutex)(&backlight_dev_list_mutex); -static void backlight_unregister_fb(struct backlight_device *bd) -{ - fb_unregister_client(&bd->fb_notif); -} -#else -static inline int backlight_register_fb(struct backlight_device *bd) -{ - return 0; + list_for_each_entry(bd, &backlight_dev_list, entry) + backlight_notify_blank(bd, display_dev, fb_on, prev_fb_on); } - -static inline void backlight_unregister_fb(struct backlight_device *bd) -{ -} -#endif /* CONFIG_FB_CORE */ +EXPORT_SYMBOL(backlight_notify_blank_all); static void backlight_generate_event(struct backlight_device *bd, enum backlight_update_reason reason) @@ -455,12 +401,6 @@ struct backlight_device *backlight_device_register(const char *name, return ERR_PTR(rc); } - rc = backlight_register_fb(new_bd); - if (rc) { - device_unregister(&new_bd->dev); - return ERR_PTR(rc); - } - new_bd->ops = ops; #ifdef CONFIG_PMAC_BACKLIGHT @@ -547,7 +487,6 @@ void backlight_device_unregister(struct backlight_device *bd) bd->ops = NULL; mutex_unlock(&bd->ops_lock); - backlight_unregister_fb(bd); device_unregister(&bd->dev); } EXPORT_SYMBOL(backlight_device_unregister); diff --git a/drivers/video/fbdev/core/fb_backlight.c b/drivers/video/fbdev/core/fb_backlight.c index 6fdaa9f81be9..dbed9696f4c5 100644 --- a/drivers/video/fbdev/core/fb_backlight.c +++ b/drivers/video/fbdev/core/fb_backlight.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0-or-later +#include #include #include #include @@ -36,4 +37,15 @@ struct backlight_device *fb_bl_device(struct fb_info *info) return info->bl_dev; } EXPORT_SYMBOL(fb_bl_device); + +void fb_bl_notify_blank(struct fb_info *info, int old_blank) +{ + bool on = info->blank == FB_BLANK_UNBLANK; + bool prev_on = old_blank == FB_BLANK_UNBLANK; + + if (info->bl_dev) + backlight_notify_blank(info->bl_dev, info->device, on, prev_on); + else + backlight_notify_blank_all(info->device, on, prev_on); +} #endif diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 9650b641d8e8..c931f270ac34 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -363,6 +363,8 @@ int fb_blank(struct fb_info *info, int blank) if (ret) goto err; + fb_bl_notify_blank(info, old_blank); + fb_notifier_call_chain(FB_EVENT_BLANK, &event); return 0; diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 03723a5478f8..10e626db7eee 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -12,7 +12,6 @@ #include #include #include -#include #include /** @@ -278,11 +277,6 @@ struct backlight_device { */ const struct backlight_ops *ops; - /** - * @fb_notif: The framebuffer notifier block - */ - struct notifier_block fb_notif; - /** * @entry: List entry of all registered backlight devices */ @@ -400,6 +394,22 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type); int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness); +#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE) +void backlight_notify_blank(struct backlight_device *bd, + struct device *display_dev, + bool fb_on, bool prev_fb_on); +void backlight_notify_blank_all(struct device *display_dev, + bool fb_on, bool prev_fb_on); +#else +static inline void backlight_notify_blank(struct backlight_device *bd, + struct device *display_dev, + bool fb_on, bool prev_fb_on) +{ } +static inline void backlight_notify_blank_all(struct device *display_dev, + bool fb_on, bool prev_fb_on) +{ } +#endif + #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev) /** diff --git a/include/linux/fb.h b/include/linux/fb.h index 348aa2e146e2..835e13d6eba8 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -758,11 +758,15 @@ extern void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max) #if IS_ENABLED(CONFIG_FB_BACKLIGHT) struct backlight_device *fb_bl_device(struct fb_info *info); +void fb_bl_notify_blank(struct fb_info *info, int old_blank); #else static inline struct backlight_device *fb_bl_device(struct fb_info *info) { return NULL; } + +static inline void fb_bl_notify_blank(struct fb_info *info, int old_blank) +{ } #endif static inline struct lcd_device *fb_lcd_device(struct fb_info *info) -- cgit v1.2.3-59-g8ed1b From bc70cc84f5a2ebfd7e7112e9b8837e0c7954fc65 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Fri, 21 Mar 2025 10:54:01 +0100 Subject: backlight: lcd: Replace fb events with a dedicated function call Remove support for fb events from the lcd subsystem. Provide the helper lcd_notify_blank_all() instead. In fbdev, call lcd_notify_blank_all() to inform the lcd subsystem of changes to a display's blank state. Fbdev maintains a list of all installed notifiers. Instead of fbdev notifiers, maintain an internal list of lcd devices. v3: - export lcd_notify_mode_change_all() (kernel test robot) v2: - maintain global list of lcd devices - avoid IS_REACHABLE() in source file - use lock guards - initialize lcd list and list mutex Signed-off-by: Thomas Zimmermann Acked-by: Simona Vetter Reviewed-by: "Daniel Thompson (RISCstar)" Link: https://lore.kernel.org/r/20250321095517.313713-9-tzimmermann@suse.de Signed-off-by: Lee Jones --- drivers/video/backlight/lcd.c | 98 +++++++++++----------------------------- drivers/video/fbdev/core/fbmem.c | 39 ++++++++++++++-- include/linux/lcd.h | 21 +++++++-- 3 files changed, 79 insertions(+), 79 deletions(-) (limited to 'include') diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c index f57ff8bcc2fa..affe5c52471a 100644 --- a/drivers/video/backlight/lcd.c +++ b/drivers/video/backlight/lcd.c @@ -15,9 +15,11 @@ #include #include #include -#include #include +static DEFINE_MUTEX(lcd_dev_list_mutex); +static LIST_HEAD(lcd_dev_list); + static void lcd_notify_blank(struct lcd_device *ld, struct device *display_dev, int power) { @@ -31,6 +33,17 @@ static void lcd_notify_blank(struct lcd_device *ld, struct device *display_dev, ld->ops->set_power(ld, power); } +void lcd_notify_blank_all(struct device *display_dev, int power) +{ + struct lcd_device *ld; + + guard(mutex)(&lcd_dev_list_mutex); + + list_for_each_entry(ld, &lcd_dev_list, entry) + lcd_notify_blank(ld, display_dev, power); +} +EXPORT_SYMBOL(lcd_notify_blank_all); + static void lcd_notify_mode_change(struct lcd_device *ld, struct device *display_dev, unsigned int width, unsigned int height) { @@ -44,75 +57,17 @@ static void lcd_notify_mode_change(struct lcd_device *ld, struct device *display ld->ops->set_mode(ld, width, height); } -#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \ - defined(CONFIG_LCD_CLASS_DEVICE_MODULE)) -static int to_lcd_power(int fb_blank) +void lcd_notify_mode_change_all(struct device *display_dev, + unsigned int width, unsigned int height) { - switch (fb_blank) { - case FB_BLANK_UNBLANK: - return LCD_POWER_ON; - /* deprecated; TODO: should become 'off' */ - case FB_BLANK_NORMAL: - return LCD_POWER_REDUCED; - case FB_BLANK_VSYNC_SUSPEND: - return LCD_POWER_REDUCED_VSYNC_SUSPEND; - /* 'off' */ - case FB_BLANK_HSYNC_SUSPEND: - case FB_BLANK_POWERDOWN: - default: - return LCD_POWER_OFF; - } -} + struct lcd_device *ld; -/* This callback gets called when something important happens inside a - * framebuffer driver. We're looking if that important event is blanking, - * and if it is, we're switching lcd power as well ... - */ -static int fb_notifier_callback(struct notifier_block *self, - unsigned long event, void *data) -{ - struct lcd_device *ld = container_of(self, struct lcd_device, fb_notif); - struct fb_event *evdata = data; - struct fb_info *info = evdata->info; - struct lcd_device *fb_lcd = fb_lcd_device(info); - - if (fb_lcd && fb_lcd != ld) - return 0; - - if (event == FB_EVENT_BLANK) { - int power = to_lcd_power(*(int *)evdata->data); - - lcd_notify_blank(ld, info->device, power); - } else { - const struct fb_videomode *videomode = evdata->data; - - lcd_notify_mode_change(ld, info->device, videomode->xres, videomode->yres); - } + guard(mutex)(&lcd_dev_list_mutex); - return 0; + list_for_each_entry(ld, &lcd_dev_list, entry) + lcd_notify_mode_change(ld, display_dev, width, height); } - -static int lcd_register_fb(struct lcd_device *ld) -{ - memset(&ld->fb_notif, 0, sizeof(ld->fb_notif)); - ld->fb_notif.notifier_call = fb_notifier_callback; - return fb_register_client(&ld->fb_notif); -} - -static void lcd_unregister_fb(struct lcd_device *ld) -{ - fb_unregister_client(&ld->fb_notif); -} -#else -static int lcd_register_fb(struct lcd_device *ld) -{ - return 0; -} - -static inline void lcd_unregister_fb(struct lcd_device *ld) -{ -} -#endif /* CONFIG_FB */ +EXPORT_SYMBOL(lcd_notify_mode_change_all); static ssize_t lcd_power_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -263,11 +218,8 @@ struct lcd_device *lcd_device_register(const char *name, struct device *parent, return ERR_PTR(rc); } - rc = lcd_register_fb(new_ld); - if (rc) { - device_unregister(&new_ld->dev); - return ERR_PTR(rc); - } + guard(mutex)(&lcd_dev_list_mutex); + list_add(&new_ld->entry, &lcd_dev_list); return new_ld; } @@ -284,10 +236,12 @@ void lcd_device_unregister(struct lcd_device *ld) if (!ld) return; + guard(mutex)(&lcd_dev_list_mutex); + list_del(&ld->entry); + mutex_lock(&ld->ops_lock); ld->ops = NULL; mutex_unlock(&ld->ops_lock); - lcd_unregister_fb(ld); device_unregister(&ld->dev); } diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index c931f270ac34..001662c606d7 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -15,6 +15,7 @@ #include #include #include +#include #include