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Date:   Mon, 24 Aug 2020 00:42:36 +0200
From:   Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
To:     Andreas Kemnade <andreas@kemnade.info>
Cc:     Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>,
        linux-kernel@vger.kernel.org, Lee Jones <lee.jones@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Heiko Stuebner <heiko.stuebner@theobroma-systems.com>,
        Stephan Gerhold <stephan@gerhold.net>,
        Lubomir Rintel <lkundrak@v3.sk>,
        Mark Brown <broonie@kernel.org>, allen <allen.chen@ite.com.tw>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        devicetree@vger.kernel.org, linux-pwm@vger.kernel.org,
        linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Heiko Stuebner <heiko@sntech.de>,
        Josua Mayer <josua.mayer@jm0.eu>
Subject: Re: [RFC PATCH 05/10] dt-bindings: pwm: Add bindings for PWM
 function in Netronix EC
Message-ID: <20200823224236.GD103070@latitude>
References: <20200620224222.1312520-1-j.neuschaefer@gmx.net>
 <20200620224222.1312520-4-j.neuschaefer@gmx.net>
 <20200621204123.6c761d98@aktux>
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On Sun, Jun 21, 2020 at 08:41:23PM +0200, Andreas Kemnade wrote:
> On Sun, 21 Jun 2020 00:42:16 +0200
> Jonathan Neusch=C3=A4fer <j.neuschaefer@gmx.net> wrote:
>=20
> > The Netronix embedded controller as found in Kobo Aura and Tolino Shine
> > supports one PWM channel, which is used to control the frontlight
> > brightness on these devices.
> >=20
> > Known problems:
> > - `make dt_binding_check` shows the following warnings:
> >   Documentation/devicetree/bindings/mfd/netronix,ntxec.example.dts:49.1=
7-42:
> >   Warning (pwms_property): /example-0/backlight:pwms: cell 2 is not a
> >   phandle reference
> >   Documentation/devicetree/bindings/mfd/netronix,ntxec.example.dts:49.1=
7-42:
> >   Warning (pwms_property): /example-0/backlight:pwms: Could not get
> >   phandle node for (cell 2)
> >=20
> In the tolino sources in ./drivers/misc/ntx-misc.c I find this line
>=20
>         if(4=3D=3DgptHWCFG->m_val.bFL_PWM) {
>=20
> No idea what it does but I would expect to have a kind of translation to
> a dt property?

As far as I understand it, FL_PWM=3D4 means that there is a second PWM
channel, in order to provide different backlight colors.

I think it should be possible to simply extend the binding to list
another available PWM channel, once we add support for such hardware.

> > +                    ec_pwm: pwm {
> > +                            compatible =3D "netronix,ntxec-pwm";
> > +                            #pwm-cells =3D <1>;
> shouldn't that be 2?
> > +                    };
> >              };
> >      };
> > +
> > +    backlight {
> > +            compatible =3D "pwm-backlight";
> > +            pwms =3D <&ec_pwm 0 50000>;
> since you have 2 values after the &ec_pwm=20
[...]
> > +properties:
> > +  compatible:
> > +    const: netronix,ntxec-pwm
> > +
> > +  "#pwm-cells":
> > +    const: 1
>=20
> shouln't that be 2?

Right, I'll fix that.


Thanks,
Jonathan

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