linux-kernel - Re: [PATCH] dt-bindings: pwm: st: convert sti-pwm to DT schema

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Message-ID: <20230803085645.svrrcritdifbjwdz@pengutronix.de>
Date:   Thu, 3 Aug 2023 10:56:45 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Raphaël Gallais-Pou <rgallaispou@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: pwm: st: convert sti-pwm to DT schema

On Thu, Aug 03, 2023 at 09:18:14AM +0200, Raphaël Gallais-Pou wrote:
> Hi
> 
> Le 02/08/2023 à 10:02, Uwe Kleine-König a écrit :
> > Hello,
> > 
> > On Wed, Aug 02, 2023 at 12:05:59AM +0200, Raphael Gallais-Pou wrote:
> > > +  st,capture-num-chan:
> > > +    $ref: "/schemas/types.yaml#/definitions/uint32"
> > > +    description: Number of available Capture channels.
> > 
> > I have the theory that nobody actually uses the capture feature and I'd
> > like to get rid of it. People who do use it, should better switch to the
> > counter driver.
> 
> TBH I only found two drivers using it, including this one.
> 
> $ grep -rinI "\.capture" drivers/pwm/ | wc -l
> 2

Right, there is pwm-stm32 and pwm-sti that support capture.

There are a few machines that have a st,sti-pwm device:

	$ grep -rl st,sti-pwm arch/arm/boot/dts/*.dtb
	arch/arm/boot/dts/stih407-b2120.dtb
	arch/arm/boot/dts/stih410-b2120.dtb
	arch/arm/boot/dts/stih410-b2260.dtb
	arch/arm/boot/dts/stih418-b2199.dtb
	arch/arm/boot/dts/stih418-b2264.dtb

but to actually use capture the device tree must have a property
st,capture-num-chan. "st,capture-num-chan" isn't set by any of the
devices.

I think for stm32 it's not that trivial to show that it's unused.
While the capture code isn't a big maintenance burden, I still would
prefer to get rid of it if nobody uses it. Still more given that there
are better alternatives available.

> If there is no opposition about removing this feature I suggest to do it in
> a second time, in a serie.

Does that mean you will do that? I guess not, but at least this means
you're not using capture support.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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