Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.32 as permitted sender) client-ip=23.128.96.32;
From:   Flavio Suligoi <f.suligoi@asem.it>
To:     Conor Dooley <conor@kernel.org>
CC:     Lee Jones <lee@kernel.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Helge Deller <deller@gmx.de>, Pavel Machek <pavel@ucw.cz>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 1/1] dt-bindings: backlight: mp3309c: remove two required
 properties
Thread-Topic: [PATCH 1/1] dt-bindings: backlight: mp3309c: remove two required
 properties
Thread-Index: AQHaA10IhwE5ZkDArkS4RoPMFlMBm7BS1g+AgARFCAA=
Date:   Mon, 23 Oct 2023 09:28:03 +0000
Message-ID: <DU2PR01MB803498DFD93E82DD3947D72DF9D8A@DU2PR01MB8034.eurprd01.prod.exchangelabs.com>
References: <20231020135434.2598578-1-f.suligoi@asem.it>
 <20231020135434.2598578-2-f.suligoi@asem.it>
 <20231020-moonrise-senate-86d0edb2d404@spud>
In-Reply-To: <20231020-moonrise-senate-86d0edb2d404@spud>
Accept-Language: it-IT, en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?H+vv07Mkm505hq2oxnZ7TOJWr6dZDquYHE5F4lV62nLkIdu8OxnprXExdjEX?=
 =?us-ascii?Q?H3SjQjWtJV52NirpycnNKqv/xhdpp26bsijNSuPRvRicsi0bfr80UQMvfHx5?=
 =?us-ascii?Q?l/h2WMgyiaG9z9vks3eXzHvaF9ygbAEGf0SwOrQdmDtU0xCCgWAs1WYzWAaN?=
 =?us-ascii?Q?q47omqkufj59PoYUNRlEAWDIebPjWxw15GlpLW4nckUS3CrueLyYXwR7A4Em?=
 =?us-ascii?Q?ybo4bTN5pSA9NpQcwWMuLBteMune1wK8kP+9NMVl/jZ4jyz9Omi7B0U+hmnn?=
 =?us-ascii?Q?uvUEpHMDO1cKaqyEULuAuWUFVAiAe1lI8qQpzE39ydh4g4P9Sra1h9+VLlkp?=
 =?us-ascii?Q?7rQX/iNx+10wy4rXJsqileRJrJJpeA6HmXB/NAVUzv8CBVAzidj4Bf2xuig6?=
 =?us-ascii?Q?z5F05YnnSeWZjHg78JHCXjyuWTQf8mU/GxKLSl64DkFBBplOIofVfx0V3gkZ?=
 =?us-ascii?Q?8FqE2WF4JSC2/wCwc5MZi1vk5i+t/r4t/gzHP3APDVHCtObWikQhCk+WSenB?=
 =?us-ascii?Q?y0HWsbCNSd2El+WqYgC+NigDkZg12tyifSedJ6/k9OfARhbmQyDYeBeumAXP?=
 =?us-ascii?Q?eVOSiaRJruTgJix6MeBrYtg6vJsb1FGImVJ9CijZ7dPZbSCdaXYUqpDRDOr8?=
 =?us-ascii?Q?KUEqnlykqLAhpS7uHTSiVviLO7N4W4HUVn9r96AGBTgaFuvZXlMw7uKasGjq?=
 =?us-ascii?Q?9sM/p6U1GCmLLRUc8Jwkch5hlWAQrTS8cDzaagGfFN3JuuoTkPOaw2hQX0yP?=
 =?us-ascii?Q?8bknV3KH8eci2bpals/CCIXhjgedvwMOhraauVgfuRkt8WwSzLMX/68flw/q?=
 =?us-ascii?Q?ulTrdYc/ZTajt9HCB3O3hbOFt0f3thamyVHJ4c4E6Ak8lui3Sy33ip62evQb?=
 =?us-ascii?Q?dw74HYN0wmnbl+W1kDhpyUebj1eJfK8eLOo1mqhcrNLo3nnSSmQjUa5lA8gn?=
 =?us-ascii?Q?JCYl/YZqFcrVPGo1foRogcZSklZS5HtiMTB6p6Pm8tj70jF//tWiiPZbYVgN?=
 =?us-ascii?Q?NyaG6GufbsDzjVLOqxyf+D0v3gR4vl1h/XghE0vsQ0wV0GrG5snd3ICUjaZ0?=
 =?us-ascii?Q?6Unua821q8HF1qCQ9KBOkXEifK5Nd8E+SOp/TX4tIlEEfm46rASLI1U5lmMr?=
 =?us-ascii?Q?B3JmLyT6k9v+qVrhtYas8/XgZyMizS46Wj6ZUMd//V2L3UkBdv0U0gYUhRe3?=
 =?us-ascii?Q?mGCIM6oRu2ES6sckUEve4qMQlGQ9ekSCkaDT/EV40MxHp6aywpBaZnfCoCqN?=
 =?us-ascii?Q?4zNRRRSejrOeJkaUOEc7SyFuDgz6XydL/bK4MJvgI/obA+qA8xsBX2cpNl6X?=
 =?us-ascii?Q?n2zhCXhvFuGTWUzlK+G+p94lVOnxgovRJHjCXXphos653qGu2cNwkXtun2Xa?=
 =?us-ascii?Q?jqbBnPAdn7b8NunPQAwEsyEPK3yOgGw1Ujded3p+r9q7oADM5L4htDjrPppM?=
 =?us-ascii?Q?OY85OfAouMOhbo59hyXtztkwP0jjVAe/nnJolg8GU6Q/Y7gqGgXQiPHSPEVb?=
 =?us-ascii?Q?s938FLYN62liAvttghoOf2766BfKqMVm5YDWUcxY1oQmMf3bT7/k+VvMaRp0?=
 =?us-ascii?Q?TFu2OvLGpbfh6hI2Wmk=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: asem.it
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: DU2PR01MB8034.eurprd01.prod.exchangelabs.com
X-MS-Exchange-CrossTenant-Network-Message-Id: eb3e2b97-e52a-4bfa-5409-08dbd3aa5b73
X-MS-Exchange-CrossTenant-originalarrivaltime: 23 Oct 2023 09:28:03.4908
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: d0a766c6-7992-4344-a4a2-a467a7bb1ed2
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: +5l3ihTdy+/skH0RcsuEZgNS1LVUDCboabDMJs2aGVy4BgWsD0HQ+7C/otgkGK/diVE4bXm+KCpH6b6Ug1yEbw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PA4PR01MB8993
X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
	DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,
	SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no
	version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Mon, 23 Oct 2023 02:28:19 -0700 (PDT)

Hi Conor,

...

> On Fri, Oct 20, 2023 at 03:54:33PM +0200, Flavio Suligoi wrote:
> > The two properties:
> >
> > - max-brightness
> > - default brightness
> >
> > are not really required, so they can be removed from the "required"
> > section.
>=20
> Why are they not required? You need to provide an explanation.

The "max-brightness" is not more used now in the driver (I used it in the f=
irst version
of the driver).
The "default-brightness", if omitted in the DT, is managed by the device dr=
iver,
using a default value. This depends on the dimming mode used:

- for the "analog mode", via I2C commands, this value is fixed by hardware =
(=3D31)
- while in case of pwm mode the default used is the last value of the=20
  brightness-levels array.

Also the brightness-levels array is not required; if it is omitted, the dri=
ver uses=20
a default array of 0..255 and the "default-brightness" is the last one, whi=
ch is "255".

> > Other changes:
> >
> > - improve the backlight working mode description, in the "description"
> >   section
>=20
> > - update the example, removing the "max-brightness" and introducing the
> >   "brightess-levels" property
>=20
> Why is this more useful?

I introduced the "brightness-levels" instead of "max-brightness" for homoge=
neity,
since the "analog mode" dimming has a brightness-levels array fixed by hard=
ware (0..31).
In this way also the "pwm" mode can use the same concepts of array of level=
s.

>=20
> Cheers,
> Conor.

Thanks for your help.
Flavio.

>=20
> >
> > Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
> > ---
> >  .../bindings/leds/backlight/mps,mp3309c.yaml           | 10 ++++------
> >  1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git
> a/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> > index 4191e33626f5..527a37368ed7 100644
> > ---
> a/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> > +++
> b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> > @@ -14,8 +14,8 @@ description: |
> >    programmable switching frequency to optimize efficiency.
> >    It supports two different dimming modes:
> >
> > -  - analog mode, via I2C commands (default)
> > -  - PWM controlled mode.
> > +  - analog mode, via I2C commands, as default mode (32 dimming levels)
> > +  - PWM controlled mode (optional)
> >
> >    The datasheet is available at:
> >    https://www.monolithicpower.com/en/mp3309c.html
> > @@ -50,8 +50,6 @@ properties:
> >  required:
> >    - compatible
> >    - reg
> > -  - max-brightness
> > -  - default-brightness
> >
> >  unevaluatedProperties: false
> >
> > @@ -66,8 +64,8 @@ examples:
> >              compatible =3D "mps,mp3309c";
> >              reg =3D <0x17>;
> >              pwms =3D <&pwm1 0 3333333 0>; /* 300 Hz --> (1/f) * 1*10^9=
 */
> > -            max-brightness =3D <100>;
> > -            default-brightness =3D <80>;
> > +            brightness-levels =3D <0 4 8 16 32 64 128 255>;
> > +            default-brightness =3D <6>;
> >              mps,overvoltage-protection-microvolt =3D <24000000>;
> >          };
> >      };
> > --
> > 2.34.1
> >