On 11/23/2012 10:44 AM, Peter Ujfalusi wrote: > Hi Grant, > > On 11/23/2012 10:13 AM, Peter Ujfalusi wrote: >> Hi Grant, >> >> On 11/23/2012 08:55 AM, Grant Likely wrote: >>> Ugh. and this is why I wanted the PWM and GPIO subsystems to use the >>> same namespace and binding. <grumble, mutter> But that's not your fault. >>> >>> It's pretty horrible to have a separate translator node to convert a PWM >>> into a GPIO (with output only of course). The gpio properties should >>> appear directly in the PWM node itself and the translation code should >>> be in either the pwm or the gpio core. I don't think it should look like >>> a separate device. >> >> Let me see if I understand your suggestion correctly. In the DT you suggest >> something like this: >> >> twl_pwmled: pwmled { >> compatible = "ti,twl4030-pwmled"; >> #pwm-cells = <2>; >> #gpio-cells = <2>; >> gpio-controller; >> }; > > After I thought about this.. Is this what we really want? > After all what we have here is a PWM generator used to emulate a GPIO signal. > The PWM itself can be used for driving a LED (standard LED or backlight and we > have DT bindings for these already), vibra motor, or other things. > If we combine the PWM with GPIO we should go and 'bloat' the DT node to also > include all sort of other uses of PWM at once? > > IMHO it is better to keep them as separate things. > pwm node to describe the PWM generator, > separate nodes to describe it's uses like led, backlight, motor and gpio. > The difference here is that the LED, backlight, etc are all different physical devices begin driven by the pwm pin, so it makes sense to have a device tree node for them, while using the pwm as gpio is just a different function of the same physical pin. So in a sense the pwm controller also becomes a gpio controller. I like the idea of the pwm core automatically instantiating a pwm-gpo device if it sees a gpio-controller property in the pwm device devicetree node. - Lars -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html