[PATCH v4 00/11] backlight, lcd, led: Remove fbdev dependencies

[PATCH v4 00/11] backlight, lcd, led: Remove fbdev dependencies

[Thomas Zimmermann]

This series removes the remaining dependencies on fbdev from the
backlight, lcd and led subsystems. Each depends on fbdev events to
track display state. Make fbdev inform each subsystem via a dedicated
interface instead.

Patches 1 to 3 make fbdev track blank state for each display, so that
backlight code doesn't have to.

Patches 4 to 6 remove fbdev event handling from backlight code. Patches
7 and 8 remove fbdev event handling from lcd code and patches 9 and 10
do the same for led's backlight trigger.

The final patch removes the event constants from fbdev.

With the series applied, the three subsystems do no longer depend on
fbdev. It's also a clean up for fbdev. Fbdev used to send out a large
number of events. That mechanism has been deprecated for some time and
converted call to dedicated functions instead.

Testing is very welcome, as I don't have the hardware to test this
series.

v4:
- protect backlight declarations with IS_REACHABLE()
v3:
- export several symbols
- static-inline declare empty placeholders
v2:
- avoid IS_REACHABLE() in source file (Lee)
- simplify several interfaces and helpers
- use lock guards
- initialize global lists and mutices

Thomas Zimmermann (11):
  fbdev: Rework fb_blank()
  fbdev: Track display blanking state
  fbdev: Send old blank state in FB_EVENT_BLANK
  backlight: Implement fbdev tracking with blank state from event
  backlight: Move blank-state handling into helper
  backlight: Replace fb events with a dedicated function call
  backlight: lcd: Move event handling into helpers
  backlight: lcd: Replace fb events with a dedicated function call
  leds: backlight trigger: Move blank-state handling into helper
  leds: backlight trigger: Replace fb events with a dedicated function
    call
  fbdev: Remove constants of unused events

 drivers/leds/trigger/ledtrig-backlight.c |  48 +++++-----
 drivers/video/backlight/backlight.c      |  93 +++++--------------
 drivers/video/backlight/lcd.c            | 108 +++++++++--------------
 drivers/video/fbdev/core/fb_backlight.c  |  12 +++
 drivers/video/fbdev/core/fb_info.c       |   1 +
 drivers/video/fbdev/core/fbmem.c         |  82 ++++++++++++++---
 drivers/video/fbdev/core/fbsysfs.c       |   8 +-
 include/linux/backlight.h                |  32 +++----
 include/linux/fb.h                       |  12 +--
 include/linux/lcd.h                      |  21 ++++-
 include/linux/leds.h                     |   6 ++
 11 files changed, 215 insertions(+), 208 deletions(-)

-- 
2.48.1

[PATCH v4 01/11] fbdev: Rework fb_blank()

[Thomas Zimmermann]

Reimplement fb_blank() to return early on errors. No functional
changes. Prepares the helper for tracking the blanking state in
struct fb_info.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/video/fbdev/core/fbmem.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 3c568cff2913..39e2b81473ad 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -339,11 +339,13 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 }
 EXPORT_SYMBOL(fb_set_var);
 
-int
-fb_blank(struct fb_info *info, int blank)
+int fb_blank(struct fb_info *info, int blank)
 {
 	struct fb_event event;
-	int ret = -EINVAL;
+	int ret;
+
+	if (!info->fbops->fb_blank)
+		return -EINVAL;
 
 	if (blank > FB_BLANK_POWERDOWN)
 		blank = FB_BLANK_POWERDOWN;
@@ -351,13 +353,13 @@ fb_blank(struct fb_info *info, int blank)
 	event.info = info;
 	event.data = &blank;
 
-	if (info->fbops->fb_blank)
-		ret = info->fbops->fb_blank(blank, info);
+	ret = info->fbops->fb_blank(blank, info);
+	if (ret)
+		return ret;
 
-	if (!ret)
-		fb_notifier_call_chain(FB_EVENT_BLANK, &event);
+	fb_notifier_call_chain(FB_EVENT_BLANK, &event);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(fb_blank);
 
-- 
2.48.1

[PATCH v4 02/11] fbdev: Track display blanking state

[Thomas Zimmermann]

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 <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/video/fbdev/core/fb_info.c |  1 +
 drivers/video/fbdev/core/fbmem.c   | 17 ++++++++++++++++-
 drivers/video/fbdev/core/fbsysfs.c |  8 ++++----
 include/linux/fb.h                 |  2 ++
 4 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/video/fbdev/core/fb_info.c b/drivers/video/fbdev/core/fb_info.c
index 4847ebe50d7d..52f9bd2c5417 100644
--- a/drivers/video/fbdev/core/fb_info.c
+++ b/drivers/video/fbdev/core/fb_info.c
@@ -42,6 +42,7 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
 
 	info->device = dev;
 	info->fbcon_rotate_hint = -1;
+	info->blank = FB_BLANK_UNBLANK;
 
 #if IS_ENABLED(CONFIG_FB_BACKLIGHT)
 	mutex_init(&info->bl_curve_mutex);
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 39e2b81473ad..5d1529d300b7 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -341,6 +341,7 @@ EXPORT_SYMBOL(fb_set_var);
 
 int fb_blank(struct fb_info *info, int blank)
 {
+	int old_blank = info->blank;
 	struct fb_event event;
 	int ret;
 
@@ -353,13 +354,19 @@ int fb_blank(struct fb_info *info, int blank)
 	event.info = info;
 	event.data = &blank;
 
+	info->blank = blank;
+
 	ret = info->fbops->fb_blank(blank, info);
 	if (ret)
-		return ret;
+		goto err;
 
 	fb_notifier_call_chain(FB_EVENT_BLANK, &event);
 
 	return 0;
+
+err:
+	info->blank = old_blank;
+	return ret;
 }
 EXPORT_SYMBOL(fb_blank);
 
@@ -408,6 +415,14 @@ static int do_register_framebuffer(struct fb_info *fb_info)
 	mutex_init(&fb_info->lock);
 	mutex_init(&fb_info->mm_lock);
 
+	/*
+	 * With an fb_blank callback present, we assume that the
+	 * display is blank, so that fb_blank() enables it on the
+	 * first modeset.
+	 */
+	if (fb_info->fbops->fb_blank)
+		fb_info->blank = FB_BLANK_POWERDOWN;
+
 	fb_device_create(fb_info);
 
 	if (fb_info->pixmap.addr == NULL) {
diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c
index 1b3c9958ef5c..e337660bce46 100644
--- a/drivers/video/fbdev/core/fbsysfs.c
+++ b/drivers/video/fbdev/core/fbsysfs.c
@@ -242,11 +242,11 @@ static ssize_t store_blank(struct device *device,
 	return count;
 }
 
-static ssize_t show_blank(struct device *device,
-			  struct device_attribute *attr, char *buf)
+static ssize_t show_blank(struct device *device, struct device_attribute *attr, char *buf)
 {
-//	struct fb_info *fb_info = dev_get_drvdata(device);
-	return 0;
+	struct fb_info *fb_info = dev_get_drvdata(device);
+
+	return sysfs_emit(buf, "%d\n", fb_info->blank);
 }
 
 static ssize_t store_console(struct device *device,
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 5ba187e08cf7..f41d3334ac23 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -471,6 +471,8 @@ 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,
-- 
2.48.1

[PATCH v4 03/11] fbdev: Send old blank state in FB_EVENT_BLANK

[Thomas Zimmermann]

The event FB_EVENT_BLANK sends the new blank state in the event's
data field. Also send the old state. It's an additional field in the
data array; existing receivers won't notice the difference.

The backlight subsystem currently tracks blank state per display per
backlight. That is not optimal as it ties backlight code to fbdev. A
subsystem should not track internal state of another subsystem. With
both, new and old, blank state in FB_EVENT_BLANK, the backlight code
will not require its own state tracker any longer.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/video/fbdev/core/fbmem.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 5d1529d300b7..9650b641d8e8 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -343,6 +343,7 @@ int fb_blank(struct fb_info *info, int blank)
 {
 	int old_blank = info->blank;
 	struct fb_event event;
+	int data[2];
 	int ret;
 
 	if (!info->fbops->fb_blank)
@@ -351,8 +352,10 @@ int fb_blank(struct fb_info *info, int blank)
 	if (blank > FB_BLANK_POWERDOWN)
 		blank = FB_BLANK_POWERDOWN;
 
+	data[0] = blank;
+	data[1] = old_blank;
 	event.info = info;
-	event.data = &blank;
+	event.data = data;
 
 	info->blank = blank;
 
-- 
2.48.1

[PATCH v4 04/11] backlight: Implement fbdev tracking with blank state from event

[Thomas Zimmermann]

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 <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/video/backlight/backlight.c | 14 +++++++-------
 include/linux/backlight.h           | 10 +---------
 2 files changed, 8 insertions(+), 16 deletions(-)

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;
 };
-- 
2.48.1

[PATCH v4 05/11] backlight: Move blank-state handling into helper

[Thomas Zimmermann]

Move the handling of blank-state updates into a separate helper,
so that is can be called without the fbdev event. No functional
changes.

As a minor improvement over the original code, the update replaces
manual locking with a guard.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/video/backlight/backlight.c | 46 +++++++++++++++++------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index bb01f57c4683..1c43f579396f 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -80,6 +80,30 @@ static const char *const backlight_scale_types[] = {
 
 #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)
+{
+	guard(mutex)(&bd->ops_lock);
+
+	if (!bd->ops)
+		return;
+	if (bd->ops->controls_device && !bd->ops->controls_device(bd, display_dev))
+		return;
+
+	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_on && prev_fb_on && bd->use_count) {
+		if (!(--bd->use_count)) {
+			bd->props.state |= BL_CORE_FBBLANK;
+			backlight_update_status(bd);
+		}
+	}
+}
+
 /*
  * fb_notifier_callback
  *
@@ -107,31 +131,15 @@ static int fb_notifier_callback(struct notifier_block *self,
 		return 0;
 
 	bd = container_of(self, struct backlight_device, fb_notif);
-	mutex_lock(&bd->ops_lock);
 
-	if (!bd->ops)
-		goto out;
-	if (bd->ops->controls_device && !bd->ops->controls_device(bd, info->device))
-		goto out;
 	if (fb_bd && fb_bd != bd)
-		goto out;
+		return 0;
 
 	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_on && prev_fb_on && bd->use_count) {
-		if (!(--bd->use_count)) {
-			bd->props.state |= BL_CORE_FBBLANK;
-			backlight_update_status(bd);
-		}
-	}
-out:
-	mutex_unlock(&bd->ops_lock);
+	backlight_notify_blank(bd, info->device, fb_on, prev_fb_on);
+
 	return 0;
 }
 
-- 
2.48.1

[PATCH v4 06/11] backlight: Replace fb events with a dedicated function call

[Thomas Zimmermann]

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 <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 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(-)

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 <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;
@@ -78,11 +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 <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
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 <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)
 
 /**
diff --git a/include/linux/fb.h b/include/linux/fb.h
index f41d3334ac23..d45bd220cb8f 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -757,11 +757,15 @@ 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)
-- 
2.48.1

Re: [PATCH v4 06/11] backlight: Replace fb events with a dedicated function call

[Daniel Thompson]

On Fri, Mar 21, 2025 at 10:53:59AM +0100, Thomas Zimmermann wrote:
> 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)

I was convinced by the replies to other things in v4. Thanks!

> v3:
> - declare empty fb_bl_notify_blank() as static inline (kernel test robot)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Acked-by: Simona Vetter <simona.vetter@ffwll.ch>


Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>


Daniel.

[PATCH v4 07/11] backlight: lcd: Move event handling into helpers

[Thomas Zimmermann]

Move the handling of display updates to separate helper functions.
There is code for handling fbdev blank events and fbdev mode changes.
The code currently runs from fbdev event notifiers, which will be
replaced.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/video/backlight/lcd.c | 38 ++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index 3267acf8dc5b..f57ff8bcc2fa 100644
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -18,6 +18,32 @@
 #include <linux/fb.h>
 #include <linux/slab.h>
 
+static void lcd_notify_blank(struct lcd_device *ld, struct device *display_dev,
+			     int power)
+{
+	guard(mutex)(&ld->ops_lock);
+
+	if (!ld->ops || !ld->ops->set_power)
+		return;
+	if (ld->ops->controls_device && !ld->ops->controls_device(ld, display_dev))
+		return;
+
+	ld->ops->set_power(ld, power);
+}
+
+static void lcd_notify_mode_change(struct lcd_device *ld, struct device *display_dev,
+				   unsigned int width, unsigned int height)
+{
+	guard(mutex)(&ld->ops_lock);
+
+	if (!ld->ops || !ld->ops->set_mode)
+		return;
+	if (ld->ops->controls_device && !ld->ops->controls_device(ld, display_dev))
+		return;
+
+	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)
@@ -50,25 +76,17 @@ static int fb_notifier_callback(struct notifier_block *self,
 	struct fb_info *info = evdata->info;
 	struct lcd_device *fb_lcd = fb_lcd_device(info);
 
-	guard(mutex)(&ld->ops_lock);
-
-	if (!ld->ops)
-		return 0;
-	if (ld->ops->controls_device && !ld->ops->controls_device(ld, info->device))
-		return 0;
 	if (fb_lcd && fb_lcd != ld)
 		return 0;
 
 	if (event == FB_EVENT_BLANK) {
 		int power = to_lcd_power(*(int *)evdata->data);
 
-		if (ld->ops->set_power)
-			ld->ops->set_power(ld, power);
+		lcd_notify_blank(ld, info->device, power);
 	} else {
 		const struct fb_videomode *videomode = evdata->data;
 
-		if (ld->ops->set_mode)
-			ld->ops->set_mode(ld, videomode->xres, videomode->yres);
+		lcd_notify_mode_change(ld, info->device, videomode->xres, videomode->yres);
 	}
 
 	return 0;
-- 
2.48.1

[PATCH v4 08/11] backlight: lcd: Replace fb events with a dedicated function call

[Thomas Zimmermann]

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 <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 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(-)

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 <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)
+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 <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);
 
diff --git a/include/linux/lcd.h b/include/linux/lcd.h
index c3ccdff4519a..d4fa03722b72 100644
--- a/include/linux/lcd.h
+++ b/include/linux/lcd.h
@@ -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)
-- 
2.48.1

Re: [PATCH v4 08/11] backlight: lcd: Replace fb events with a dedicated function call

[Daniel Thompson]

On Fri, Mar 21, 2025 at 10:54:01AM +0100, Thomas Zimmermann wrote:
> 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 <tzimmermann@suse.de>
> Acked-by: Simona Vetter <simona.vetter@ffwll.ch>

Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>


Daniel.

Re: [PATCH v4 08/11] backlight: lcd: Replace fb events with a dedicated function call

[Thomas Zimmermann]

Hi

Am 21.03.25 um 12:27 schrieb Daniel Thompson:
> On Fri, Mar 21, 2025 at 10:54:01AM +0100, Thomas Zimmermann wrote:
>> 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 <tzimmermann@suse.de>
>> Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
> Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>

Thanks for reviewing.  There are reviews of all patches. If nothing else 
comes in, feel free to merge it via the backlight tree.  I can also take 
the series into dri-devel.

Best regards
Thomas

>
>
> Daniel.
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Re: [PATCH v4 08/11] backlight: lcd: Replace fb events with a dedicated function call

[Lee Jones]

On Mon, 24 Mar 2025, Thomas Zimmermann wrote:

> Hi
> 
> Am 21.03.25 um 12:27 schrieb Daniel Thompson:
> > On Fri, Mar 21, 2025 at 10:54:01AM +0100, Thomas Zimmermann wrote:
> > > 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 <tzimmermann@suse.de>
> > > Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
> > Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
> 
> Thanks for reviewing.  There are reviews of all patches. If nothing else
> comes in, feel free to merge it via the backlight tree.  I can also take the
> series into dri-devel.

I plan to take this in via the Backlight tree.  Once applied, I'll send
out a pull-request for other maintainers to pull from.

For the record, just so we're clear, this will not make v6.15.

-- 
Lee Jones [李琼斯]

Re: [PATCH v4 08/11] backlight: lcd: Replace fb events with a dedicated function call

[Thomas Zimmermann]

Hi

Am 28.03.25 um 09:42 schrieb Lee Jones:
> On Mon, 24 Mar 2025, Thomas Zimmermann wrote:
>
>> Hi
>>
>> Am 21.03.25 um 12:27 schrieb Daniel Thompson:
>>> On Fri, Mar 21, 2025 at 10:54:01AM +0100, Thomas Zimmermann wrote:
>>>> 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 <tzimmermann@suse.de>
>>>> Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
>>> Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
>> Thanks for reviewing.  There are reviews of all patches. If nothing else
>> comes in, feel free to merge it via the backlight tree.  I can also take the
>> series into dri-devel.
> I plan to take this in via the Backlight tree.  Once applied, I'll send
> out a pull-request for other maintainers to pull from.
>
> For the record, just so we're clear, this will not make v6.15.

Makes sense. Thanks a lot.

Best regards
Thomas

>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

[PATCH v4 09/11] leds: backlight trigger: Move blank-state handling into helper

[Thomas Zimmermann]

Move the handling of blank-state updates into a separate helper,
so that is can be called without the fbdev event. No functional
changes.

v2:
- rename helper to avoid renaming in a later patch (Lee)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/leds/trigger/ledtrig-backlight.c | 30 ++++++++++++++----------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 487577d22cfc..8e66d55a6c82 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -25,12 +25,28 @@ struct bl_trig_notifier {
 	unsigned invert;
 };
 
+static void ledtrig_backlight_notify_blank(struct bl_trig_notifier *n, int new_status)
+{
+	struct led_classdev *led = n->led;
+
+	if (new_status == n->old_status)
+		return;
+
+	if ((n->old_status == UNBLANK) ^ n->invert) {
+		n->brightness = led->brightness;
+		led_set_brightness_nosleep(led, LED_OFF);
+	} else {
+		led_set_brightness_nosleep(led, n->brightness);
+	}
+
+	n->old_status = new_status;
+}
+
 static int fb_notifier_callback(struct notifier_block *p,
 				unsigned long event, void *data)
 {
 	struct bl_trig_notifier *n = container_of(p,
 					struct bl_trig_notifier, notifier);
-	struct led_classdev *led = n->led;
 	struct fb_event *fb_event = data;
 	int *blank;
 	int new_status;
@@ -42,17 +58,7 @@ static int fb_notifier_callback(struct notifier_block *p,
 	blank = fb_event->data;
 	new_status = *blank ? BLANK : UNBLANK;
 
-	if (new_status == n->old_status)
-		return 0;
-
-	if ((n->old_status == UNBLANK) ^ n->invert) {
-		n->brightness = led->brightness;
-		led_set_brightness_nosleep(led, LED_OFF);
-	} else {
-		led_set_brightness_nosleep(led, n->brightness);
-	}
-
-	n->old_status = new_status;
+	ledtrig_backlight_notify_blank(n, new_status);
 
 	return 0;
 }
-- 
2.48.1

[PATCH v4 10/11] leds: backlight trigger: Replace fb events with a dedicated function call

[Thomas Zimmermann]

Remove support for fb events from the led backlight trigger. Provide
the helper ledtrig_backlight_blank() instead. Call it from fbdev to
inform the trigger of changes to a display's blank state.

Fbdev maintains a list of all installed notifiers. Instead of the fbdev
notifiers, maintain an internal list of led backlight triggers.

v3:
- export ledtrig_backlight_blank()
v2:
- maintain global list of led backlight triggers (Lee)
- avoid IS_REACHABLE() in source file (Lee)
- notify on changes to blank state instead of display state
- use lock guards
- initialize led list and list mutex

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 drivers/leds/trigger/ledtrig-backlight.c | 42 ++++++++++--------------
 drivers/video/fbdev/core/fbmem.c         | 19 ++++++-----
 include/linux/leds.h                     |  6 ++++
 3 files changed, 33 insertions(+), 34 deletions(-)

diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 8e66d55a6c82..c1f0f5becaee 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -10,7 +10,6 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/init.h>
-#include <linux/fb.h>
 #include <linux/leds.h>
 #include "../leds.h"
 
@@ -21,10 +20,14 @@ struct bl_trig_notifier {
 	struct led_classdev *led;
 	int brightness;
 	int old_status;
-	struct notifier_block notifier;
 	unsigned invert;
+
+	struct list_head entry;
 };
 
+static DEFINE_MUTEX(ledtrig_backlight_list_mutex);
+static LIST_HEAD(ledtrig_backlight_list);
+
 static void ledtrig_backlight_notify_blank(struct bl_trig_notifier *n, int new_status)
 {
 	struct led_classdev *led = n->led;
@@ -42,26 +45,17 @@ static void ledtrig_backlight_notify_blank(struct bl_trig_notifier *n, int new_s
 	n->old_status = new_status;
 }
 
-static int fb_notifier_callback(struct notifier_block *p,
-				unsigned long event, void *data)
+void ledtrig_backlight_blank(bool blank)
 {
-	struct bl_trig_notifier *n = container_of(p,
-					struct bl_trig_notifier, notifier);
-	struct fb_event *fb_event = data;
-	int *blank;
-	int new_status;
-
-	/* If we aren't interested in this event, skip it immediately ... */
-	if (event != FB_EVENT_BLANK)
-		return 0;
-
-	blank = fb_event->data;
-	new_status = *blank ? BLANK : UNBLANK;
+	struct bl_trig_notifier *n;
+	int new_status = blank ? BLANK : UNBLANK;
 
-	ledtrig_backlight_notify_blank(n, new_status);
+	guard(mutex)(&ledtrig_backlight_list_mutex);
 
-	return 0;
+	list_for_each_entry(n, &ledtrig_backlight_list, entry)
+		ledtrig_backlight_notify_blank(n, new_status);
 }
+EXPORT_SYMBOL(ledtrig_backlight_blank);
 
 static ssize_t bl_trig_invert_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -106,8 +100,6 @@ ATTRIBUTE_GROUPS(bl_trig);
 
 static int bl_trig_activate(struct led_classdev *led)
 {
-	int ret;
-
 	struct bl_trig_notifier *n;
 
 	n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
@@ -118,11 +110,9 @@ static int bl_trig_activate(struct led_classdev *led)
 	n->led = led;
 	n->brightness = led->brightness;
 	n->old_status = UNBLANK;
-	n->notifier.notifier_call = fb_notifier_callback;
 
-	ret = fb_register_client(&n->notifier);
-	if (ret)
-		dev_err(led->dev, "unable to register backlight trigger\n");
+	guard(mutex)(&ledtrig_backlight_list_mutex);
+	list_add(&n->entry, &ledtrig_backlight_list);
 
 	return 0;
 }
@@ -131,7 +121,9 @@ static void bl_trig_deactivate(struct led_classdev *led)
 {
 	struct bl_trig_notifier *n = led_get_trigger_data(led);
 
-	fb_unregister_client(&n->notifier);
+	guard(mutex)(&ledtrig_backlight_list_mutex);
+	list_del(&n->entry);
+
 	kfree(n);
 }
 
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 001662c606d7..f089f72ec75a 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -16,6 +16,7 @@
 #include <linux/fb.h>
 #include <linux/fbcon.h>
 #include <linux/lcd.h>
+#include <linux/leds.h>
 
 #include <video/nomodeset.h>
 
@@ -369,11 +370,17 @@ static void fb_lcd_notify_blank(struct fb_info *info)
 	lcd_notify_blank_all(info->device, power);
 }
 
+static void fb_ledtrig_backlight_notify_blank(struct fb_info *info)
+{
+	if (info->blank == FB_BLANK_UNBLANK)
+		ledtrig_backlight_blank(false);
+	else
+		ledtrig_backlight_blank(true);
+}
+
 int fb_blank(struct fb_info *info, int blank)
 {
 	int old_blank = info->blank;
-	struct fb_event event;
-	int data[2];
 	int ret;
 
 	if (!info->fbops->fb_blank)
@@ -382,11 +389,6 @@ int fb_blank(struct fb_info *info, int blank)
 	if (blank > FB_BLANK_POWERDOWN)
 		blank = FB_BLANK_POWERDOWN;
 
-	data[0] = blank;
-	data[1] = old_blank;
-	event.info = info;
-	event.data = data;
-
 	info->blank = blank;
 
 	ret = info->fbops->fb_blank(blank, info);
@@ -395,8 +397,7 @@ int fb_blank(struct fb_info *info, int blank)
 
 	fb_bl_notify_blank(info, old_blank);
 	fb_lcd_notify_blank(info);
-
-	fb_notifier_call_chain(FB_EVENT_BLANK, &event);
+	fb_ledtrig_backlight_notify_blank(info);
 
 	return 0;
 
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 98f9719c924c..b3f0aa081064 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -640,6 +640,12 @@ static inline void ledtrig_flash_ctrl(bool on) {}
 static inline void ledtrig_torch_ctrl(bool on) {}
 #endif
 
+#if IS_REACHABLE(CONFIG_LEDS_TRIGGER_BACKLIGHT)
+void ledtrig_backlight_blank(bool blank);
+#else
+static inline void ledtrig_backlight_blank(bool blank) {}
+#endif
+
 /*
  * Generic LED platform data for describing LED names and default triggers.
  */
-- 
2.48.1

[PATCH v4 11/11] fbdev: Remove constants of unused events

[Thomas Zimmermann]

The constants FB_EVENT_MODE_CHANGE and FB_EVENT_BLANK are unused.
Remove them from the header file.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
---
 include/linux/fb.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/include/linux/fb.h b/include/linux/fb.h
index d45bd220cb8f..2497321e30bb 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -129,18 +129,12 @@ struct fb_cursor_user {
  * Register/unregister for framebuffer events
  */
 
-/*	The resolution of the passed in fb_info about to change */
-#define FB_EVENT_MODE_CHANGE		0x01
-
 #ifdef CONFIG_GUMSTIX_AM200EPD
 /* only used by mach-pxa/am200epd.c */
 #define FB_EVENT_FB_REGISTERED          0x05
 #define FB_EVENT_FB_UNREGISTERED        0x06
 #endif
 
-/*      A display blank is requested       */
-#define FB_EVENT_BLANK                  0x09
-
 struct fb_event {
 	struct fb_info *info;
 	void *data;
-- 
2.48.1

Re: [PATCH v4 00/11] backlight, lcd, led: Remove fbdev dependencies

[Lee Jones]

On Fri, 21 Mar 2025 10:53:53 +0100, Thomas Zimmermann wrote:
> This series removes the remaining dependencies on fbdev from the
> backlight, lcd and led subsystems. Each depends on fbdev events to
> track display state. Make fbdev inform each subsystem via a dedicated
> interface instead.
> 
> Patches 1 to 3 make fbdev track blank state for each display, so that
> backlight code doesn't have to.
> 
> [...]

Applied, thanks!

[01/11] fbdev: Rework fb_blank()
        commit: 93e41f968d7c6ea1cedc6b365917cbb787ef08f6
[02/11] fbdev: Track display blanking state
        commit: 7e3711eb87c584ed224a7ad7000eba36e6fa3a51
[03/11] fbdev: Send old blank state in FB_EVENT_BLANK
        commit: dfb4bf1ac40162ff5ea3715a10f6af2dcf3030c5
[04/11] backlight: Implement fbdev tracking with blank state from event
        commit: 726491f2038ec71122d45700f3abf36fdb277aaa
[05/11] backlight: Move blank-state handling into helper
        commit: 4bfb77f3381627640e97e0e423c93a2ea93e7de7
[06/11] backlight: Replace fb events with a dedicated function call
        commit: b01beb2f1f6bcda17634a5b529865ffc5a9b795f
[07/11] backlight: lcd: Move event handling into helpers
        commit: e98696cea7e289447a5d2328546b947629301616
[08/11] backlight: lcd: Replace fb events with a dedicated function call
        commit: bc70cc84f5a2ebfd7e7112e9b8837e0c7954fc65
[09/11] leds: backlight trigger: Move blank-state handling into helper
        commit: 28f8bab711c0984005a6dd4cc980b4ba8409b817
[10/11] leds: backlight trigger: Replace fb events with a dedicated function call
        commit: dc2139c0aa3283e5749109641af1878ed7bf7371
[11/11] fbdev: Remove constants of unused events
        commit: d32a0b567a8a8b6e677d35c4f8eb8bd32b7029a0

--
Lee Jones [李琼斯]

Re: [PATCH v4 00/11] backlight, lcd, led: Remove fbdev dependencies

[Lee Jones]

On Thu, 10 Apr 2025, Lee Jones wrote:

> On Fri, 21 Mar 2025 10:53:53 +0100, Thomas Zimmermann wrote:
> > This series removes the remaining dependencies on fbdev from the
> > backlight, lcd and led subsystems. Each depends on fbdev events to
> > track display state. Make fbdev inform each subsystem via a dedicated
> > interface instead.
> > 
> > Patches 1 to 3 make fbdev track blank state for each display, so that
> > backlight code doesn't have to.
> > 
> > [...]
> 
> Applied, thanks!
> 
> [01/11] fbdev: Rework fb_blank()
>         commit: 93e41f968d7c6ea1cedc6b365917cbb787ef08f6
> [02/11] fbdev: Track display blanking state
>         commit: 7e3711eb87c584ed224a7ad7000eba36e6fa3a51
> [03/11] fbdev: Send old blank state in FB_EVENT_BLANK
>         commit: dfb4bf1ac40162ff5ea3715a10f6af2dcf3030c5
> [04/11] backlight: Implement fbdev tracking with blank state from event
>         commit: 726491f2038ec71122d45700f3abf36fdb277aaa
> [05/11] backlight: Move blank-state handling into helper
>         commit: 4bfb77f3381627640e97e0e423c93a2ea93e7de7
> [06/11] backlight: Replace fb events with a dedicated function call
>         commit: b01beb2f1f6bcda17634a5b529865ffc5a9b795f
> [07/11] backlight: lcd: Move event handling into helpers
>         commit: e98696cea7e289447a5d2328546b947629301616
> [08/11] backlight: lcd: Replace fb events with a dedicated function call
>         commit: bc70cc84f5a2ebfd7e7112e9b8837e0c7954fc65
> [09/11] leds: backlight trigger: Move blank-state handling into helper
>         commit: 28f8bab711c0984005a6dd4cc980b4ba8409b817
> [10/11] leds: backlight trigger: Replace fb events with a dedicated function call
>         commit: dc2139c0aa3283e5749109641af1878ed7bf7371
> [11/11] fbdev: Remove constants of unused events
>         commit: d32a0b567a8a8b6e677d35c4f8eb8bd32b7029a0

Okay, these have been submitted for build testing.

Once complete, I'll send out a PR.

Note to self: ib-backlight-leds-fbdev-6.16

-- 
Lee Jones [李琼斯]

[GIT PULL] Immutable branch between Backlight, fbdev and LEDs for the v6.16 merge window

[Lee Jones]

Enjoy!

The following changes since commit 0af2f6be1b4281385b618cb86ad946eded089ac8:

  Linux 6.15-rc1 (2025-04-06 13:11:33 -0700)

are available in the Git repository at:

  ssh://git@gitolite.kernel.org/pub/scm/linux/kernel/git/lee/backlight.git tags/ib-backlight-leds-fbdev-v6.16

for you to fetch changes up to d32a0b567a8a8b6e677d35c4f8eb8bd32b7029a0:

  fbdev: Remove constants of unused events (2025-04-10 10:39:14 +0100)

----------------------------------------------------------------
Immutable branch between Backlight, fbdev and LEDs for the v6.16 merge window

----------------------------------------------------------------
Thomas Zimmermann (11):
      fbdev: Rework fb_blank()
      fbdev: Track display blanking state
      fbdev: Send old blank state in FB_EVENT_BLANK
      backlight: Implement fbdev tracking with blank state from event
      backlight: Move blank-state handling into helper
      backlight: Replace fb events with a dedicated function call
      backlight: lcd: Move event handling into helpers
      backlight: lcd: Replace fb events with a dedicated function call
      leds: backlight trigger: Move blank-state handling into helper
      leds: backlight trigger: Replace fb events with a dedicated function call
      fbdev: Remove constants of unused events

 drivers/leds/trigger/ledtrig-backlight.c |  48 +++++++-------
 drivers/video/backlight/backlight.c      |  93 ++++++--------------------
 drivers/video/backlight/lcd.c            | 108 ++++++++++++-------------------
 drivers/video/fbdev/core/fb_backlight.c  |  12 ++++
 drivers/video/fbdev/core/fb_info.c       |   1 +
 drivers/video/fbdev/core/fbmem.c         |  82 +++++++++++++++++++----
 drivers/video/fbdev/core/fbsysfs.c       |   8 +--
 include/linux/backlight.h                |  32 ++++-----
 include/linux/fb.h                       |  12 ++--
 include/linux/lcd.h                      |  21 +++++-
 include/linux/leds.h                     |   6 ++
 11 files changed, 215 insertions(+), 208 deletions(-)

-- 
Lee Jones [李琼斯]