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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 <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>
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Include <linux/of.h> to declare struct of_count_phandle_with_args().
Avoids dependency on backlight header to include it.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: "Daniel Thompson (RISCstar)" <danielt@kernel.org>
Link: https://lore.kernel.org/r/20250715122643.137027-13-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
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Replace calls of devm_kzalloc() with devm_kcalloc() in led_bl_get_leds()
and led_bl_parse_levels() for safer memory allocation with built-in
overflow protection.
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: "Daniel Thompson (RISCstar)" <danielt@kernel.org>
Link: https://lore.kernel.org/r/20250819035804.433615-1-rongqianfeng@vivo.com
Signed-off-by: Lee Jones <lee@kernel.org>
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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 <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>
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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>
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Replace FB_BLANK_ constants with their counterparts from the
backlight subsystem. The values are identical, so there's no
change in functionality.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20240624152033.25016-11-tzimmermann@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
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The driver depends on CONFIG_OF, it is not necessary to use
of_match_ptr() here.
Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20230818012308.2058373-1-ruanjinjie@huawei.com
Signed-off-by: Lee Jones <lee@kernel.org>
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The led_access lock must be held when calling led_sysfs_enable() and
led_sysfs_disable(). This fixes warnings such as this:
[ 2.432495] ------------[ cut here ]------------
[ 2.437316] WARNING: CPU: 0 PID: 22 at drivers/leds/led-core.c:349 led_sysfs_disable+0x54/0x58
[ 2.446105] Modules linked in:
[ 2.449218] CPU: 0 PID: 22 Comm: kworker/u2:1 Not tainted 6.3.8+ #1
[ 2.456268] Hardware name: Generic AM3517 (Flattened Device Tree)
[ 2.462402] Workqueue: events_unbound deferred_probe_work_func
[ 2.468353] unwind_backtrace from show_stack+0x10/0x14
[ 2.473632] show_stack from dump_stack_lvl+0x24/0x2c
[ 2.478759] dump_stack_lvl from __warn+0x9c/0xc4
[ 2.483551] __warn from warn_slowpath_fmt+0x64/0xc0
[ 2.488586] warn_slowpath_fmt from led_sysfs_disable+0x54/0x58
[ 2.494567] led_sysfs_disable from led_bl_probe+0x20c/0x3b0
[ 2.500305] led_bl_probe from platform_probe+0x5c/0xb8
[ 2.505615] platform_probe from really_probe+0xc8/0x2a0
[ 2.510986] really_probe from __driver_probe_device+0x88/0x19c
[ 2.516967] __driver_probe_device from driver_probe_device+0x30/0xcc
[ 2.523498] driver_probe_device from __device_attach_driver+0x94/0xc4
[ 2.530090] __device_attach_driver from bus_for_each_drv+0x80/0xcc
[ 2.536437] bus_for_each_drv from __device_attach+0xf8/0x19c
[ 2.542236] __device_attach from bus_probe_device+0x8c/0x90
[ 2.547973] bus_probe_device from deferred_probe_work_func+0x80/0xb0
[ 2.554504] deferred_probe_work_func from process_one_work+0x228/0x4c0
[ 2.561187] process_one_work from worker_thread+0x1fc/0x4d0
[ 2.566925] worker_thread from kthread+0xb4/0xd0
[ 2.571685] kthread from ret_from_fork+0x14/0x2c
[ 2.576446] Exception stack(0xd0079fb0 to 0xd0079ff8)
[ 2.581573] 9fa0: 00000000 00000000 00000000 00000000
[ 2.589813] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.598052] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 2.604888] ---[ end trace 0000000000000000 ]---
Signed-off-by: Mans Rullgard <mans@mansr.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20230619160249.10414-1-mans@mansr.com
Signed-off-by: Lee Jones <lee@kernel.org>
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The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.
Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230308073945.2336302-7-u.kleine-koenig@pengutronix.de
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Introduce the backlight_get_brightness() helper in all
video/backlight/* drivers. This simplifies the code and align the
implementation of the update_status() operation across the different
backlight drivers.
Some of the drivers gains a little extra functionality by the change
as they now respect the fb_blank() ioctl.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
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This patch adds a led-backlight driver (led_bl), which is similar to
pwm_bl except the driver uses a LED class driver to adjust the
brightness in the HW. Multiple LEDs can be used for a single backlight.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Tony Lindgren <tony@atomide.com>
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