Re: [RFC 1/4] pwm: sifive: Add DT documentation for SiFive PWM Controller.

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On 10/16/18 3:51 AM, Thierry Reding wrote:
On Mon, Oct 15, 2018 at 03:45:46PM -0700, Atish Patra wrote:
On 10/10/18 6:51 AM, Thierry Reding wrote:
On Tue, Oct 09, 2018 at 11:51:22AM -0700, Atish Patra wrote:
[...]
+- interrupts: one interrupt per PWM channel (currently unused in the driver)

This should probably say what the interrupt is used for. And once you
have that, remove the comment about it being unused in the driver. DT
is OS agnostic, so "driver" is very unspecific and your claim may
actually be false.

Thierry

As per my understanding, they are generated by hardware but no usage of pwm
interrupts as of now.

It might be useful to say when they are generated. Are they generated
once per period? At the beginning or the end of the period? That kind
of thing.


Sure. I might have over simplified the statement above.
I could only find this about pwm interrupts in spec.
"The PWM can be configured to provide periodic counter interrupts by enabling auto-zeroing of the count register when a comparator 0 fires"

I may be wrong here but it looks like we need to configure the hardware to generate periodic interrupts. I will confirm with Wesly and update it in v2.

I am not sure if removing the entire entry is a good idea.
What would be the best way to represent that information ?

May be this ?

+-interrupts: one interrupt per PWM channel. No usage in HiFive Unleashed
SoC.

Why do you think you need to say that they are unused? If the hardware
generates these interrupts, then they are "used". If no driver currently
has a use for them, that's driver specific and doesn't belong in the DT
bindings.


Sounds good. I will update accordingly.

Regards,
Atish
Thierry





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