linux-stable.git/drivers/video/backlight, branch v6.17

backlight: pm8941: Add NULL check in wled_configure()

2025-04-15T17:27:38+00:00

devm_kasprintf() returns NULL when memory allocation fails. Currently,
wled_configure() does not check for this case, which results in a NULL
pointer dereference.

Add NULL check after devm_kasprintf() to prevent this issue.

Fixes: f86b77583d88 ("backlight: pm8941: Convert to using %pOFn instead of device_node.name")
Signed-off-by: Henry Martin 
Reviewed-by: Dmitry Baryshkov 
Reviewed-by: "Daniel Thompson (RISCstar)" 
Link: https://lore.kernel.org/r/20250401091647.22784-1-bsdhenrymartin@gmail.com
Signed-off-by: Lee Jones

backlight: lcd: Replace fb events with a dedicated function call

2025-04-10T09:39:10+00:00

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

backlight: lcd: Move event handling into helpers

2025-04-10T09:39:09+00:00

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 
Reviewed-by: "Daniel Thompson (RISCstar)" 
Acked-by: Simona Vetter 
Link: https://lore.kernel.org/r/20250321095517.313713-8-tzimmermann@suse.de
Signed-off-by: Lee Jones

backlight: Replace fb events with a dedicated function call

2025-04-10T09:39:03+00:00

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

backlight: Move blank-state handling into helper

2025-04-10T09:39:01+00:00

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 
Reviewed-by: "Daniel Thompson (RISCstar)" 
Acked-by: Simona Vetter 
Link: https://lore.kernel.org/r/20250321095517.313713-6-tzimmermann@suse.de
Signed-off-by: Lee Jones

backlight: Implement fbdev tracking with blank state from event

2025-04-10T09:39:00+00:00

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

backlight: pcf50633-backlight: Remove unused driver

2025-03-14T11:36:33+00:00

The pcf50633 was used as part of the OpenMoko devices but
the support for its main chip was recently removed in:
commit 61b7f8920b17 ("ARM: s3c: remove all s3c24xx support")

See https://lore.kernel.org/all/Z8z236h4B5A6Ki3D@gallifrey/

Remove it.

Signed-off-by: "Dr. David Alan Gilbert" 
Link: https://lore.kernel.org/r/20250311014959.743322-8-linux@treblig.org
Signed-off-by: Lee Jones

backlight: tdo24m: Eliminate redundant whitespace

2025-03-14T10:53:54+00:00

The description for CONFIG_LCD_TDO24M has redundant whitespace.
Trim it to keep the code tidy.

Signed-off-by: WangYuli 
Link: https://lore.kernel.org/r/8FC39A4DC2529591+20250310045636.14329-1-wangyuli@uniontech.com
Signed-off-by: Lee Jones

backlight: apple_dwi_bl: Add Apple DWI backlight driver

2025-02-20T15:14:29+00:00

Add driver for backlight controllers attached via Apple DWI 2-wire
interface, which is found on some Apple iPhones, iPads and iPod touches
with a LCD display.

Although there is an existing apple_bl driver, it is for backlight
controllers on Intel Macs attached via PCI, which is completely different
from the Samsung-derived DWI block.

Reviewed-by: "Daniel Thompson (RISCstar)" 
Signed-off-by: Nick Chan 
Reviewed-by: Neal Gompa 
Link: https://lore.kernel.org/r/20250214040306.16312-3-towinchenmi@gmail.com
Signed-off-by: Lee Jones

backlight: led_bl: Hold led_access lock when calling led_sysfs_disable()

2025-02-11T14:12:38+00:00

Lockdep detects the following issue on led-backlight removal:
  [  142.315935] ------------[ cut here ]------------
  [  142.315954] WARNING: CPU: 2 PID: 292 at drivers/leds/led-core.c:455 led_sysfs_enable+0x54/0x80
  ...
  [  142.500725] Call trace:
  [  142.503176]  led_sysfs_enable+0x54/0x80 (P)
  [  142.507370]  led_bl_remove+0x80/0xa8 [led_bl]
  [  142.511742]  platform_remove+0x30/0x58
  [  142.515501]  device_remove+0x54/0x90
  ...

Indeed, led_sysfs_enable() has to be called with the led_access
lock held.

Hold the lock when calling led_sysfs_disable().

Fixes: ae232e45acf9 ("backlight: add led-backlight driver")
Cc: stable@vger.kernel.org
Signed-off-by: Herve Codina 
Link: https://lore.kernel.org/r/20250122091914.309533-1-herve.codina@bootlin.com
Signed-off-by: Lee Jones