* Arnd Bergmann wrote:
> On Thursday 15 March 2012, Nicolas Ferre wrote:
[...]
> > + i2c1: i2c@1 {
> > + ...
> > + dma-request = <&sdma 2 &sdma 3>;
> > + dma-request-names = "tx", "rx";
> > + ...
> > + };
>
> This is slightly different from how the proposed pwm binding works that
> Thierry is working on, which uses an arbitrary property name instead of
> requiring the use of a specific property but then allowing to give names
> in another property.
>
> I don't care much which way it's done, but please try to agree on one
> approach that is used for both.
>
> The one you have here is already used by reg and irq, while the other
> one is used in gpio.
I think we can just use pwm as the fixed property name. Or alternatively do
something along the lines of the regulator bindings, where we use "-pwm" as
the suffix for specifying PWM devices. For instance if a named PWM is
requested, the OF support code would look for a <name>-pwm property, while
requesting an unnamed PWM would simply look at the pwm property.
When it comes to the labelling of PWM devices, I don't think both variants
are exclusive. Currently the PWM framework uses name of the user OF device
node for the PWM label. That is, if I have the following in the DTS:
pwm {
...
};
backlight {
compatible = "pwm-backlight";
pwm = <&pwm 0 5000000>;
...
};
Then the PWM will be labelled "backlight":
$ cat cat /sys/kernel/debug/pwm
platform/tegra-pwm, 4 PWM devices
pwm-0 (backlight ): requested enabled
pwm-1 ((null) ):
pwm-2 ((null) ):
pwm-3 ((null) ):
So if we decide to explicitly allow specifying names, then we can always add
a pwm-names property (or <name>-pwm-names respectively) to use as label and
fallback to the user OF device node name if that property is not present.
Thierry
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