linux-kernel - [PATCH v2 1/1] dt-bindings: backlight: mp3309c: remove two required properties

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Message-Id: <20231025155057.886823-2-f.suligoi@asem.it>
Date:   Wed, 25 Oct 2023 17:50:57 +0200
From:   Flavio Suligoi <f.suligoi@...m.it>
To:     Lee Jones <lee@...nel.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Helge Deller <deller@....de>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Flavio Suligoi <f.suligoi@...m.it>
Subject: [PATCH v2 1/1] dt-bindings: backlight: mp3309c: remove two required properties

The two properties:

- max-brightness
- default brightness

are not really required, so they can be removed from the "required"
section.
The "max-brightness" is no longer used in the current version
of the driver (it was used only in the first version).
The "default-brightness", if omitted in the DT, is managed by the
device driver, using a default value. This value depends on the dimming
mode used:

- for the "analog mode", via I2C commands, this value is fixed by
  hardware (=31)
- while in case of pwm mode the default used is the last value of the
  brightness-levels array.

Also the brightness-levels array is not required:

- in "analog mode", via I2C commands, the brightness-level array is
  fixed by hardware (0..31).;
- in pwm dimming mode, the driver uses a default array of 0..255 and
  the "default-brightness" is the last one, which is "255"

NOTE: there are no compatibility problems with the previous version,
      since the device driver has not yet been included in any kernel.
      Only this dt-binding yaml file is already included in the
      "for-backlight-next" branch of the "backlight" kernel repository.
      No developer may have used it.

Other changes:

- improve the backlight working mode description, in the "description"
  section
- update the example, removing the "max-brightness" and introducing the
  "brightess-levels" property

Signed-off-by: Flavio Suligoi <f.suligoi@...m.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 = "mps,mp3309c";
             reg = <0x17>;
             pwms = <&pwm1 0 3333333 0>; /* 300 Hz --> (1/f) * 1*10^9 */
-            max-brightness = <100>;
-            default-brightness = <80>;
+            brightness-levels = <0 4 8 16 32 64 128 255>;
+            default-brightness = <6>;
             mps,overvoltage-protection-microvolt = <24000000>;
         };
     };
-- 
2.34.1