kernel/git/stable/linux.git/drivers/video/backlight, branch linux-6.17.y

backlight: led-bl: Add devlink to supplier LEDs

2025-12-18T12:59:56+00:00

[ Upstream commit 9341d6698f4cfdfc374fb6944158d111ebe16a9d ] LED Backlight is a consumer of one or multiple LED class devices, but devlink is currently unable to create correct supplier-producer links when the supplier is a class device. It creates instead a link where the supplier is the parent of the expected device. One consequence is that removal order is not correctly enforced. Issues happen for example with the following sections in a device tree overlay: // An LED driver chip pca9632@62 { compatible = "nxp,pca9632"; reg = <0x62>; // ... addon_led_pwm: led-pwm@3 { reg = <3>; label = "addon:led:pwm"; }; }; backlight-addon { compatible = "led-backlight"; leds = <&addon_led_pwm>; brightness-levels = <255>; default-brightness-level = <255>; }; In this example, the devlink should be created between the backlight-addon (consumer) and the pca9632@62 (supplier). Instead it is created between the backlight-addon (consumer) and the parent of the pca9632@62, which is typically the I2C bus adapter. On removal of the above overlay, the LED driver can be removed before the backlight device, resulting in: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 ... Call trace: led_put+0xe0/0x140 devm_led_release+0x6c/0x98 Another way to reproduce the bug without any device tree overlays is unbinding the LED class device (pca9632@62) before unbinding the consumer (backlight-addon): echo 11-0062 >/sys/bus/i2c/drivers/leds-pca963x/unbind echo ...backlight-dock >/sys/bus/platform/drivers/led-backlight/unbind Fix by adding a devlink between the consuming led-backlight device and the supplying LED device, as other drivers and subsystems do as well. Fixes: ae232e45acf9 ("backlight: add led-backlight driver") Signed-off-by: Luca Ceresoli Reviewed-by: Daniel Thompson (RISCstar) Reviewed-by: Herve Codina Tested-by: Alexander Sverdlin Link: https://patch.msgid.link/20250519-led-backlight-add-devlink-to-supplier-class-device-v6-1-845224aeb2ce@bootlin.com Signed-off-by: Lee Jones Signed-off-by: Sasha Levin

video: backlight: lp855x_bl: Set correct EPROM start for LP8556

2025-11-13T20:36:51+00:00

[ Upstream commit 07c7efda24453e05951fb2879f5452b720b91169 ] According to LP8556 datasheet EPROM region starts at 0x98 so adjust value in the driver accordingly. Signed-off-by: Svyatoslav Ryhel Reviewed-by: "Daniel Thompson (RISCstar)" Link: https://lore.kernel.org/r/20250909074304.92135-2-clamor95@gmail.com Signed-off-by: Lee Jones Signed-off-by: Sasha Levin

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