> I understand that period of TLC chip cannot be changed and hence cannot
> fully implement PWM interface.
O.K, so that is agreed.
> But, suppose I want to control brightness
> of an LCD screen, with your current design, my LCD driver can never can do
> something like:
> pwm_get(chip);
> pwm_update_brightness();
> pwm_remove();
> I will always have to rely on sysfs entries to control brightness.
Or you can use the kernel API for controlling leds. There is a hint in
Documentation/devicetree/bindings/leds/common.txt
- linux,default-trigger : This parameter, if present, is a
string defining the trigger assigned to the LED. Current triggers are:
"backlight" - LED will act as a back-light, controlled by the framebuffer
system
So somebody has at least thought about this, and there is
drivers/leds/trigger/ledtrig-backlight.c
What i also find interesting is:
drivers/video/backlight/adp8860_bl.c
drivers/video/backlight/adp8870_bl.c
drivers/video/backlight/lm3639_bl.c
all implement an led_class driver. So it does seem some people think
backlight LEDs can be models using the led class.
Andrew
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