Commit bc70cc84 authored by Thomas Zimmermann's avatar Thomas Zimmermann Committed by Lee Jones
Browse files

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: 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/20250321095517.313713-9-tzimmermann@suse.de


Signed-off-by: default avatarLee Jones <lee@kernel.org>
parent e98696ce

drivers/video/backlight/lcd.c

+26 −72
Original line number Diff line number Diff line
@@ -15,9 +15,11 @@ 
#include <linux/notifier.h>

#include <linux/ctype.h>

#include <linux/err.h>

#include <linux/fb.h>

#include <linux/slab.h>



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)

{

	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;

	}

}



/* 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);

	}



	return 0;

}



static int lcd_register_fb(struct lcd_device *ld)

void lcd_notify_mode_change_all(struct device *display_dev,

				unsigned int width, unsigned int height)

{

	memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));

	ld->fb_notif.notifier_call = fb_notifier_callback;

	return fb_register_client(&ld->fb_notif);

}

	struct lcd_device *ld;



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;

}

	guard(mutex)(&lcd_dev_list_mutex);



static inline void lcd_unregister_fb(struct lcd_device *ld)

{

	list_for_each_entry(ld, &lcd_dev_list, entry)

		lcd_notify_mode_change(ld, display_dev, width, height);

}

#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);

}

drivers/video/fbdev/core/fbmem.c

+35 −4
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/export.h>

#include <linux/fb.h>

#include <linux/fbcon.h>

#include <linux/lcd.h>



#include <video/nomodeset.h>
@@ -220,6 +221,12 @@ static int fb_check_caps(struct fb_info *info, struct fb_var_screeninfo *var, 
	return err;

}



static void fb_lcd_notify_mode_change(struct fb_info *info,

				      struct fb_videomode *mode)

{

	lcd_notify_mode_change_all(info->device, mode->xres, mode->yres);

}



int

fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)

{
@@ -227,7 +234,6 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) 
	u32 activate;

	struct fb_var_screeninfo old_var;

	struct fb_videomode mode;

	struct fb_event event;

	u32 unused;



	if (var->activate & FB_ACTIVATE_INV_MODE) {
@@ -331,14 +337,38 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) 
	if (ret)

		return ret;



	event.info = info;

	event.data = &mode;

	fb_notifier_call_chain(FB_EVENT_MODE_CHANGE, &event);

	fb_lcd_notify_mode_change(info, &mode);



	return 0;

}

EXPORT_SYMBOL(fb_set_var);



static void fb_lcd_notify_blank(struct fb_info *info)

{

	int power;



	switch (info->blank) {

	case FB_BLANK_UNBLANK:

		power = LCD_POWER_ON;

		break;

	/* deprecated; TODO: should become 'off' */

	case FB_BLANK_NORMAL:

		power = LCD_POWER_REDUCED;

		break;

	case FB_BLANK_VSYNC_SUSPEND:

		power = LCD_POWER_REDUCED_VSYNC_SUSPEND;

		break;

	/* 'off' */

	case FB_BLANK_HSYNC_SUSPEND:

	case FB_BLANK_POWERDOWN:

	default:

		power = LCD_POWER_OFF;

		break;

	}



	lcd_notify_blank_all(info->device, power);

}



int fb_blank(struct fb_info *info, int blank)

{

	int old_blank = info->blank;
@@ -364,6 +394,7 @@ int fb_blank(struct fb_info *info, int blank) 
		goto err;



	fb_bl_notify_blank(info, old_blank);

	fb_lcd_notify_blank(info);



	fb_notifier_call_chain(FB_EVENT_BLANK, &event);

include/linux/lcd.h

+18 −3
Original line number Diff line number Diff line
@@ -11,7 +11,6 @@ 


#include <linux/device.h>

#include <linux/mutex.h>

#include <linux/notifier.h>



#define LCD_POWER_ON			(0)

#define LCD_POWER_REDUCED		(1) // deprecated; don't use in new code
@@ -79,8 +78,11 @@ struct lcd_device { 
	const struct lcd_ops *ops;

	/* Serialise access to set_power method */

	struct mutex update_lock;

	/* The framebuffer notifier block */

	struct notifier_block fb_notif;



	/**

	 * @entry: List entry of all registered lcd devices

	 */

	struct list_head entry;



	struct device dev;

};
@@ -125,6 +127,19 @@ extern void lcd_device_unregister(struct lcd_device *ld); 
extern void devm_lcd_device_unregister(struct device *dev,

	struct lcd_device *ld);



#if IS_REACHABLE(CONFIG_LCD_CLASS_DEVICE)

void lcd_notify_blank_all(struct device *display_dev, int power);

void lcd_notify_mode_change_all(struct device *display_dev,

				unsigned int width, unsigned int height);

#else

static inline void lcd_notify_blank_all(struct device *display_dev, int power)

{}



static inline void lcd_notify_mode_change_all(struct device *display_dev,

					      unsigned int width, unsigned int height)

{}

#endif



#define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)



static inline void * lcd_get_data(struct lcd_device *ld_dev)