Commit b01beb2f authored by Thomas Zimmermann's avatar Thomas Zimmermann Committed by Lee Jones
Browse files

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: default avatarThomas Zimmermann <tzimmermann@suse.de>
Acked-by: default avatarSimona Vetter <simona.vetter@ffwll.ch>
Reviewed-by: default avatar"Daniel Thompson (RISCstar)" <danielt@kernel.org>
Link: https://lore.kernel.org/r/20250321095517.313713-7-tzimmermann@suse.de


Signed-off-by: default avatarLee Jones <lee@kernel.org>
parent 4bfb77f3

drivers/video/backlight/backlight.c

+12 −73
Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ 
#include <linux/notifier.h>

#include <linux/ctype.h>

#include <linux/err.h>

#include <linux/fb.h>

#include <linux/slab.h>



#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;
@@ -78,10 +77,7 @@ 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,

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;

	guard(mutex)(&backlight_dev_list_mutex);



	return fb_register_client(&bd->fb_notif);

	list_for_each_entry(bd, &backlight_dev_list, entry)

		backlight_notify_blank(bd, display_dev, fb_on, prev_fb_on);

}



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;

}



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);

drivers/video/fbdev/core/fb_backlight.c

+12 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later



#include <linux/backlight.h>

#include <linux/export.h>

#include <linux/fb.h>

#include <linux/mutex.h>
@@ -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

drivers/video/fbdev/core/fbmem.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/backlight.h

+16 −6
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ 
#include <linux/device.h>

#include <linux/fb.h>

#include <linux/mutex.h>

#include <linux/notifier.h>

#include <linux/types.h>



/**
@@ -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)



/**

include/linux/fb.h

+4 −0
Original line number Diff line number Diff line
@@ -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)