When building for a platform without CONFIG_PM_SLEEP, such as s390,
there are two unused function warnings:
drivers/video/backlight/aw99706.c:436:12: error: 'aw99706_resume' defined but not used [-Werror=unused-function]
436 | static int aw99706_resume(struct device *dev)
| ^~~~~~~~~~~~~~
drivers/video/backlight/aw99706.c:429:12: error: 'aw99706_suspend' defined but not used [-Werror=unused-function]
429 | static int aw99706_suspend(struct device *dev)
| ^~~~~~~~~~~~~~~
SET_SYSTEM_SLEEP_PM_OPS, used within SIMPLE_DEV_PM_OPS, expands to
nothing when CONFIG_PM_SLEEP is not set, so these functions are
completely unused in this configuration.
SIMPLE_DEV_PM_OPS is deprecated in favor of DEFINE_SIMPLE_DEV_PM_OPS,
which avoids this issue by using pm_sleep_ptr to make these callbacks
NULL when CONFIG_PM_SLEEP is unset while making the callback functions
always appear used to the compiler regardless of configuration. Switch
to DEFINE_SIMPLE_DEV_PM_OPS for aw99706_pm_ops to clear up the warning.
Additionally, wrap the pointer to aw99706_pm_ops in pm_ptr() in
aw99706_i2c_driver to ensure that the structure is completely eliminated
in configurations without CONFIG_PM.
Fixes: 88a8e9b49ee8 ("backlight: aw99706: Add support for Awinic AW99706 backlight")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20251120-backlight-aw99706-fix-unused-pm-functions-v1-1-8b9c17c4e783@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
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: ae232e45ac ("backlight: add led-backlight driver")
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://patch.msgid.link/20250519-led-backlight-add-devlink-to-supplier-class-device-v6-1-845224aeb2ce@bootlin.com
Signed-off-by: Lee Jones <lee@kernel.org>
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>
Link: https://lore.kernel.org/r/20250321095517.313713-9-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
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>
Reviewed-by: "Daniel Thompson (RISCstar)" <danielt@kernel.org>
Link: https://lore.kernel.org/r/20250321095517.313713-7-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
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>
Link: https://lore.kernel.org/r/20250321095517.313713-5-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
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)" <danielt@kernel.org>
Signed-off-by: Nick Chan <towinchenmi@gmail.com>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Link: https://lore.kernel.org/r/20250214040306.16312-3-towinchenmi@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>
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: ae232e45ac ("backlight: add led-backlight driver")
Cc: stable@vger.kernel.org
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20250122091914.309533-1-herve.codina@bootlin.com
Signed-off-by: Lee Jones <lee@kernel.org>
The continual trickle of small conversion patches is grating on me, and
is really not helping. Just get rid of the 'remove_new' member
function, which is just an alias for the plain 'remove', and had a
comment to that effect:
/*
* .remove_new() is a relic from a prototype conversion of .remove().
* New drivers are supposed to implement .remove(). Once all drivers are
* converted to not use .remove_new any more, it will be dropped.
*/
This was just a tree-wide 'sed' script that replaced '.remove_new' with
'.remove', with some care taken to turn a subsequent tab into two tabs
to make things line up.
I did do some minimal manual whitespace adjustment for places that used
spaces to line things up.
Then I just removed the old (sic) .remove_new member function, and this
is the end result. No more unnecessary conversion noise.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
backlight_register_notifier and backlight_unregister_notifier have
been unused since commit 6cb634d0dc ("ACPI: video: Remove code to
unregister acpi_video backlight when a native backlight registers")
With those not being called, it means that the backlight_notifier
list is always empty.
Remove the functions, the list itself and the enum used in the
notifications.
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20240919232758.639925-1-linux@treblig.org
Signed-off-by: Lee Jones <lee@kernel.org>
Rename check_fb in struct lcd_ops to controls_device. The callback
is now independent from fbdev's struct fb_info and tests if an lcd
device controls a hardware display device. The new naming and semantics
follow similar functionality for backlight devices.
v2:
- fix typos in commit description (Daniel)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20240906075439.98476-27-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
