Hi Conor, ... > On Mon, Oct 23, 2023 at 09:28:03AM +0000, Flavio Suligoi wrote: > > > 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. > > > > > > 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 first version of the driver). > > If it is not used any more, what happens when someone passes an old > devicetree to the kernel, that contains max-brightness, but not any of your > new properties? This is not a problem, because the device driver has not yet been included in any kernel. My patch for the device driver is still being analyzed by the maintainers. Only this dt-binding yaml file is already included in the "for-backlight-next" branch of the "backlight" kernel repository. At the moment, this driver is used only in a i.MX8MM board produced in my company, under my full control. No other developer is using it now. > > The "default-brightness", if omitted in the DT, is managed by the > > device driver, using a default value. This depends on the dimming mode > used: > > For default-brightness, has here always been support in the driver for the > property being omitted, or is this newly added? In the first version of the driver this property was a "required property", but nobody has used this driver before, so this should be not a problem. > > > - 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; if it is omitted, > > the driver uses a default array of 0..255 and the "default-brightness" is the > last one, which is "255". > > Firstly, this is the sort of rationale that needs to be put into your commit > messages, rather than bullet pointed lists of what you have done. You are absolutely right, I'll include these details in the next commit message. > > Secondly, what about other operating systems etc, do any of those support > this platform and depend on presence of these properties? I used this backlight driver in our i.MX8MM board only, with Linux only. > > > > > > > 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 > > > > > > Why is this more useful? > > > > I introduced the "brightness-levels" instead of "max-brightness" for > > homogeneity, since the "analog mode" dimming has a brightness-levels array > fixed by hardware (0..31). > > In this way also the "pwm" mode can use the same concepts of array of > levels. > > What I would like is an explanation in the commit message as to why the > revised example is more helpful than the existing (and > must-remain-valid) one. As said before, no one may have ever used this device driver, so I would leave only this new version of the example. > > Cheers, > Conor. Thanks for your help and best regards, Flavio. > > > > > > > > > > > > Signed-off-by: Flavio Suligoi <f.suligoi@xxxxxxx> > > > > --- > > > > .../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 > > > >
