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From: Atish Patra <atish.patra@wdc.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Wesley Terpstra <wesley@sifive.com>,
	palmer@sifive.com, linux-riscv@lists.infradead.org,
	linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org,
	linus.walleij@linaro.org, robh+dt@kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	mark.rutland@arm.com, hch@infradead.org
Subject: Re: [RFC 1/4] pwm: sifive: Add DT documentation for SiFive PWM Controller.
Date: Tue, 16 Oct 2018 15:42:00 -0700	[thread overview]
Message-ID: <c702cf04-a565-dc76-a3bb-dbed922a9c80@wdc.com> (raw)
In-Reply-To: <20181016105103.GB8852@ulmo>

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
> 


  reply	other threads:[~2018-10-16 22:42 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-09 18:51 [RFC 0/4] GPIO & PWM support for HiFive Unleashed Atish Patra
2018-10-09 18:51 ` [RFC 1/4] pwm: sifive: Add DT documentation for SiFive PWM Controller Atish Patra
2018-10-10 13:49   ` Thierry Reding
2018-10-15 22:57     ` Atish Patra
2018-10-15 23:19       ` Wesley Terpstra
2018-10-16 11:13         ` Thierry Reding
2018-10-16 11:01       ` Thierry Reding
2018-10-16 17:31         ` Paul Walmsley
2018-10-16 22:04           ` Thierry Reding
2018-10-16 22:20             ` Atish Patra
2018-10-17 15:58               ` Rob Herring
2018-10-17 21:45                 ` Atish Patra
2018-11-10  5:38             ` Paul Walmsley
2018-10-10 13:51   ` Thierry Reding
2018-10-15 22:45     ` Atish Patra
2018-10-16 10:51       ` Thierry Reding
2018-10-16 22:42         ` Atish Patra [this message]
2018-10-09 18:51 ` [RFC 2/4] pwm: sifive: Add a driver for SiFive SoC PWM Atish Patra
2018-10-10 13:11   ` Christoph Hellwig
2018-10-10 13:44     ` Thierry Reding
2018-10-16  6:28     ` Atish Patra
2018-10-10 14:13   ` Thierry Reding
2018-10-16  6:24     ` Atish Patra
2018-10-09 18:51 ` [RFC 3/4] gpio: sifive: Add DT documentation for SiFive GPIO Atish Patra
2018-10-09 18:51 ` [RFC 4/4] gpio: sifive: Add GPIO driver for SiFive SoCs Atish Patra
2018-10-10 12:35   ` Linus Walleij
2018-10-17  1:01     ` Atish Patra
2019-09-18  7:32       ` Bin Meng
2018-10-10 13:01   ` Andreas Schwab
2018-10-10 13:12     ` Christoph Hellwig
2018-10-10 13:28       ` Andreas Schwab

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