On Mon, Feb 11, 2013 at 07:25:05PM +1300, Tony Prisk wrote:
> I was just wondering if the following would be an acceptable way to turn
> off an lcd backlight when the pwm-backlight driver is set to level 0.
> The LCD backlight is 'powered' by the gpio.
>
> leds {
> compatible = "gpio-leds";
> backlight {
> label = "lcd-power";
> gpios = <&gpio 0 0 0>; /* bank pin active_low */
> linux,default-trigger = "backlight";
> default-state = "on";
> };
> };
>
> The method has been tested by an end-user and confirmed as working - I
> just wanted to check whether it is the 'accepted' way of doing it.I don't quite see how this is related to pwm-backlight. Maybe you can post a more complete example? Representing the backlight power as a GPIO controlled LED seems somewhat kludgy. That said, there is currently no "accepted" way to use a GPIO to control the power to the backlight in pwm-backlight. There was some work by Alex (Cc'ed) to integrate this using generic power-sequences, but there was some pushback on that. Your best bet currently would seem to integrate this with the CDF (Common Display Framework). Unfortunately that'd mean you'd need to write a whole new driver to abstract the panel. Even in CDF there are ongoing discussions about how to hook it up with the backlight framework. I know this doesn't give you a solution right away but I think it's the best way to represent the actual hardware and it takes into account a number of other aspect about displays as well. Thierry
pgpDyBG14ari0.pgp
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