RE: [PATCH 4/4] Documentation: Add device tree bindings forFreescale FTM PWM

[Xiubo Li-B47053]

Hi Stephen,


> Subject: Re: [PATCH 4/4] Documentation: Add device tree bindings for
> Freescale FTM PWM
> 
> On 08/25/2013 11:35 PM, Xiubo Li-B47053 wrote:
> >> Subject: Re: [PATCH 4/4] Documentation: Add device tree bindings for
> ...
> >>> Why do you need to manipulate the pinctrl to en/disable a channel?
> >>
> >> This is because in Vybrid VF610 TOWER board, there are 4 leds, and
> >> each led's one point(diode's positive pole) is connected to 3.3V, and
> >> the other point is connected to pwm's one channel. When the 4
> >> pinctrls are configured as enable at the same time, the 4 pinctrls is
> >> low valtage, and the 4 leds will be lighted up as default, then when
> >> you enable/disable one led will effects others.
> >>
> >> These pinctrls are belong to pwm, and I don't think led or other
> >> customer could control them directly.
> >> So, here I authorize the 4 pinctrls to each channel controls.
> >>
> > "
> > For the reason above, I have to control the pinctrls separately.
> >
> > If all the pinctrls set as default state, the 8 pinctrls must be
> controlled together.
> > And the 4 leds will all be lighted up as default and will influence
> each other.
> 
> Sorry, that still doesn't make much sense. Either way though, having
> separate pinctrl setup for a single device isn't going to work. You'll
> either need to have all combinations of 4 (8?) PWMs represented as
> pinctrl states(!), or register separate PWM devices so that they get
> independant pinctrl states.
>
Well, I have ever thought about registering separate PWM device for each channel.
But, if so, how should I control the pinctrl of each PWM(actually one channel of FTM PWM) ?
I must select "default" state(the "default" state here, the pinctrl must be setup as "dsN" or "chN-idle" state we discussed before) when probing, and when customers .request-->.config-->.enable the PWM I also must select an "active" state to config the pinctrl...
Thus, this is still not static. I think this isn't much different from the current.

Also if having all combinations of 8 PWMs represented as pinctrl states, how could I deal with the problem about LEDs ?



Thanks very much,

--
Best Regards,
Xiubo

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