Hi! It would be good to get LED backlight to work in clean way for 5.6 kernel. As far as I can see, these are neccessary (but not enough; it does not work for me): lm3532 changes to register LED with of node, plus device tree changes for droid 4, and these generic changes: commit d457d0c97d6d55fe3e62633791ac05d289a37d2e Author: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Date: Thu Oct 3 10:28:12 2019 +0200 backlight: add led-backlight driver 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@xxxxxx> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx> Acked-by: Pavel Machek <pavel@xxxxxx> Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx> commit 44b7adbf0b07904e4198ae1d0a763917d1c68a23 Author: Jean-Jacques Hiblot <jjhiblot@xxxxxx> Date: Thu Oct 3 10:28:10 2019 +0200 leds: Add managed API to get a LED from a device driver If the LED is acquired by a consumer device with devm_led_get(), it is automatically released when the device is detached. Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx> Acked-by: Pavel Machek <pavel@xxxxxx> Signed-off-by: Pavel <pavel@xxxxxx> commit 93b98c570d7f898063ab6204e1b3950a3335dd12 Author: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Date: Thu Oct 3 10:28:09 2019 +0200 leds: Add of_led_get() and led_put() This patch adds basic support for a kernel driver to get a LED device. This will be used by the led-backlight driver. Only OF version is implemented for now, and the behavior is similar to PWM's of_pwm_get() and pwm_put(). Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx> Acked-by: Pavel Machek <pavel@xxxxxx> Signed-off-by: Pavel <pavel@xxxxxx> [If you have an idea what else is needed, it would be welcome; it works for me in development tree but not in tree I'd like to upstream.] Lee, would you be willing to take "backlight: add led-backlight driver"? Would it help if I got "leds: Add managed API to get a LED from a device driver" and "leds: Add of_led_get() and led_put()" into for_next tree of the LED subsystem? It is kind of important as, well, phone without screen looks pretty much dead, and same issue hits Droid 4 and Librem 5 phones at least... Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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