Linux PWM subsystem development
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From: David Jander <david@protonic.nl>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	devicetree@vger.kernel.org, linux-doc@vger.kernel.org,
	"Nuno Sa" <nuno.sa@analog.com>,
	"Jonathan Cameron" <jic23@kernel.org>,
	"Oleksij Rempel" <o.rempel@pengutronix.de>,
	"Uwe Kleine-König" <ukleinek@kernel.org>,
	linux-pwm@vger.kernel.org
Subject: Re: [RFC PATCH 7/7] dt-bindings: motion: Add motion-simple-pwm bindings
Date: Fri, 28 Feb 2025 11:09:31 +0100	[thread overview]
Message-ID: <20250228110931.7bdae7fd@erd003.prtnl> (raw)
In-Reply-To: <9a1d75a2-66c0-46b6-91a1-4922b892dfb1@kernel.org>

On Fri, 28 Feb 2025 10:37:48 +0100
Krzysztof Kozlowski <krzk@kernel.org> wrote:

> On 28/02/2025 10:22, David Jander wrote:
> >   
> >>> +
> >>> +  motion,pwm-inverted:
> >>> +    $ref: /schemas/types.yaml#/definitions/flag    
> >>
> >> And PWM flag does not work?  
> > 
> > I have seen PWM controllers that don't seem to support the
> > PWM_POLARITY_INVERTED flag and those where it just doesn't work. Should all  
> 
> 
> Shouldn't the controllers be fixed? Or let's rephrase the question: why
> only this PWM consumer needs this property and none of others need it?

CCing Uwe Kleine-Koenig and linux-pwm mailing list.

I know that at least in kernel 6.11 the pwm-stm32.c PWM driver doesn't
properly invert the PWM signal when specifying PWM_POLARITY_INVERTED. I agree
this is a probably bug that needs fixing if still present in 6.14-rc. Besides
that, if linux-pwm agrees that every single PWM driver _must_ properly support
this flag, I will drop this consumer flag an start fixing broken PWM drivers
that I encounter. I agree that it makes more sense this way, but I wanted to
be sure.

Best regards,

-- 
David Jander

       reply	other threads:[~2025-02-28 10:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20250227162823.3585810-1-david@protonic.nl>
     [not found] ` <20250227162823.3585810-8-david@protonic.nl>
     [not found]   ` <20250228-wonderful-python-of-resistance-d5b662@krzk-bin>
     [not found]     ` <20250228102201.590b4be6@erd003.prtnl>
     [not found]       ` <9a1d75a2-66c0-46b6-91a1-4922b892dfb1@kernel.org>
2025-02-28 10:09         ` David Jander [this message]
2025-02-28 15:18           ` [RFC PATCH 7/7] dt-bindings: motion: Add motion-simple-pwm bindings Uwe Kleine-König
2025-03-03 10:53             ` Maud Spierings
2025-03-03 11:40             ` David Jander
2025-03-03 14:18               ` Krzysztof Kozlowski
2025-03-03 16:09                 ` David Jander

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