| Message ID | 20230925122609.78849-1-f.suligoi@asem.it |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/2] dt-bindings: backlight: Add MPS MP3309C | expand |
On Mon, 25 Sep 2023 14:26:08 +0200, Flavio Suligoi wrote: > The Monolithic Power (MPS) MP3309C is a WLED step-up converter, featuring a > programmable switching frequency to optimize efficiency. > The brightness can be controlled either by I2C commands (called "analog" > mode) or by a PWM input signal (PWM mode). > This driver supports both modes. > > For device driver details, please refer to: > - drivers/video/backlight/mp3309c_bl.c > > [...] Applied, thanks! [1/2] dt-bindings: backlight: Add MPS MP3309C commit: 02c4e661658f73d3c266c68f89f0b14bd8ba6bd8 -- Lee Jones [李琼斯]
Hi Daniel, ... > > +required: > > + - compatible > > + - reg > > + - max-brightness > > Why is this mandatory? > > There's no point in setting max-brightness when running in I2C mode (max- > brightness should default to 31 in that case). > > > > + - default-brightness > > Again. I'm not clear why this needs to be mandatory. > > Ok, you are right, I'll remove max-brightness and default-brightness from required properties list. I think to change these properties, for the pwm dimming, into a clearer: - brightness-levels (uint32) - default-brightness-levels (uint32). For example: brightness-levels: description: Number of brightness levels. The actual brightness level (PWM duty cycle) will be interpolated from 0 to this value. 0 means a 0% duty cycle (darkest/off), while the brightness-levels represents a 100% duty cycle (brightest). $ref: /schemas/types.yaml#/definitions/uint32 default-brightness-level: description: The default brightness level (from 0 to brightness-levels) $ref: /schemas/types.yaml#/definitions/uint32 Example: brightness-levels = <10>; default-brightness-level = <6>; What do you think about this solution? > Daniel. Thanks for your help, Flavio
On Tue, Oct 03, 2023 at 09:43:15AM +0000, Flavio Suligoi wrote: > Hi Daniel, > > ... > > > > +required: > > > + - compatible > > > + - reg > > > + - max-brightness > > > > Why is this mandatory? > > > > There's no point in setting max-brightness when running in I2C mode (max- > > brightness should default to 31 in that case). > > > > > > > + - default-brightness > > > > Again. I'm not clear why this needs to be mandatory. > > > > > > Ok, you are right, I'll remove max-brightness and default-brightness > from required properties list. I think to change these properties, > for the pwm dimming, into a clearer: > > - brightness-levels (uint32) > - default-brightness-levels (uint32). > > For example: > > brightness-levels: > description: > Number of brightness levels. The actual brightness > level (PWM duty cycle) will be interpolated from 0 to this value. > 0 means a 0% duty cycle (darkest/off), while the brightness-levels represents > a 100% duty cycle (brightest). > $ref: /schemas/types.yaml#/definitions/uint32 > > default-brightness-level: > description: > The default brightness level (from 0 to brightness-levels) > $ref: /schemas/types.yaml#/definitions/uint32 > > Example: > brightness-levels = <10>; > default-brightness-level = <6>; > > What do you think about this solution? If you want to introduce a brightness-levels property then I would expect it to be defined with the same meaning as pwm-backlight (it's not relevant to the bindings but ideally it would be implemented by refactoring and reusing the code from pwm_bl.c). Same with default-brightness-level although I'm not sure why one wouldn't just use default-brightness for new bindings (doesn't default-brightness-level simply do exactly the same thing as default-brightness). Daniel.
Hi Daniel, ... > > > > +required: > > > > + - compatible > > > > + - reg > > > > + - max-brightness > > > > > > Why is this mandatory? > > > > > > There's no point in setting max-brightness when running in I2C mode > > > (max- brightness should default to 31 in that case). > > > > > > > > > > + - default-brightness > > > > > > Again. I'm not clear why this needs to be mandatory. > > > > > > > > > > Ok, you are right, I'll remove max-brightness and default-brightness > > from required properties list. I think to change these properties, for > > the pwm dimming, into a clearer: > > > > - brightness-levels (uint32) > > - default-brightness-levels (uint32). > > > > For example: > > > > brightness-levels: > > description: > > Number of brightness levels. The actual brightness > > level (PWM duty cycle) will be interpolated from 0 to this value. > > 0 means a 0% duty cycle (darkest/off), while the brightness-levels > represents > > a 100% duty cycle (brightest). > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > default-brightness-level: > > description: > > The default brightness level (from 0 to brightness-levels) > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > Example: > > brightness-levels = <10>; > > default-brightness-level = <6>; > > > > What do you think about this solution? > > If you want to introduce a brightness-levels property then I would expect it to > be defined with the same meaning as pwm-backlight (it's not relevant to the > bindings but ideally it would be implemented by refactoring and reusing the > code from pwm_bl.c). ok, I'll use the brightness-levels property as used in pwm-backlight > > Same with default-brightness-level although I'm not sure why one wouldn't > just use default-brightness for new bindings (doesn't default-brightness-level > simply do exactly the same thing as default-brightness). ok for default-brightness instead of default-brightness-level > > > Daniel. Thanks an best regards, Flavio
Hi Daniel, ... > ... > > > > > +required: > > > > > + - compatible > > > > > + - reg > > > > > + - max-brightness > > > > > > > > Why is this mandatory? > > > > > > > > There's no point in setting max-brightness when running in I2C > > > > mode > > > > (max- brightness should default to 31 in that case). > > > > > > > > > > > > > + - default-brightness > > > > > > > > Again. I'm not clear why this needs to be mandatory. > > > > > > > > > > > > > > Ok, you are right, I'll remove max-brightness and default-brightness > > > from required properties list. I think to change these properties, > > > for the pwm dimming, into a clearer: > > > > > > - brightness-levels (uint32) > > > - default-brightness-levels (uint32). > > > > > > For example: > > > > > > brightness-levels: > > > description: > > > Number of brightness levels. The actual brightness > > > level (PWM duty cycle) will be interpolated from 0 to this value. > > > 0 means a 0% duty cycle (darkest/off), while the > > > brightness-levels > > represents > > > a 100% duty cycle (brightest). > > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > > > default-brightness-level: > > > description: > > > The default brightness level (from 0 to brightness-levels) > > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > > > Example: > > > brightness-levels = <10>; > > > default-brightness-level = <6>; > > > > > > What do you think about this solution? > > > > If you want to introduce a brightness-levels property then I would > > expect it to be defined with the same meaning as pwm-backlight (it's > > not relevant to the bindings but ideally it would be implemented by > > refactoring and reusing the code from pwm_bl.c). > > ok, I'll use the brightness-levels property as used in pwm-backlight > > > > > Same with default-brightness-level although I'm not sure why one > > wouldn't just use default-brightness for new bindings (doesn't > > default-brightness-level simply do exactly the same thing as default- > brightness). > > ok for default-brightness instead of default-brightness-level Just a question: default-brightness-level is the index into the brightness-levels array. But, if I use default-brightness instead of default-brightness-level, should I consider default-brightness also as an index into brightness-levels array? Or, in this case, have the default-brightness to be equal to one of the values inside the brightness-levels array? > > > > > > > Daniel. > > Thanks an best regards, > Flavio Thanks, Flavio
On Wed, Oct 04, 2023 at 03:18:24PM +0000, Flavio Suligoi wrote: > Hi Daniel, > ... > > ... > > > > > > +required: > > > > > > + - compatible > > > > > > + - reg > > > > > > + - max-brightness > > > > > > > > > > Why is this mandatory? > > > > > > > > > > There's no point in setting max-brightness when running in I2C > > > > > mode > > > > > (max- brightness should default to 31 in that case). > > > > > > > > > > > > > > > > + - default-brightness > > > > > > > > > > Again. I'm not clear why this needs to be mandatory. > > > > > > > > > > > > > > > > > > Ok, you are right, I'll remove max-brightness and default-brightness > > > > from required properties list. I think to change these properties, > > > > for the pwm dimming, into a clearer: > > > > > > > > - brightness-levels (uint32) > > > > - default-brightness-levels (uint32). > > > > > > > > For example: > > > > > > > > brightness-levels: > > > > description: > > > > Number of brightness levels. The actual brightness > > > > level (PWM duty cycle) will be interpolated from 0 to this value. > > > > 0 means a 0% duty cycle (darkest/off), while the > > > > brightness-levels > > > represents > > > > a 100% duty cycle (brightest). > > > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > > > > > default-brightness-level: > > > > description: > > > > The default brightness level (from 0 to brightness-levels) > > > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > > > > > Example: > > > > brightness-levels = <10>; > > > > default-brightness-level = <6>; > > > > > > > > What do you think about this solution? > > > > > > If you want to introduce a brightness-levels property then I would > > > expect it to be defined with the same meaning as pwm-backlight (it's > > > not relevant to the bindings but ideally it would be implemented by > > > refactoring and reusing the code from pwm_bl.c). > > > > ok, I'll use the brightness-levels property as used in pwm-backlight > > > > > > > > Same with default-brightness-level although I'm not sure why one > > > wouldn't just use default-brightness for new bindings (doesn't > > > default-brightness-level simply do exactly the same thing as default- > > brightness). > > > > ok for default-brightness instead of default-brightness-level > > Just a question: default-brightness-level is the index into the brightness-levels array. > But, if I use default-brightness instead of default-brightness-level, > should I consider default-brightness also as an index into brightness-levels array? Yes. > Or, in this case, have the default-brightness to be equal to one of the values inside the > brightness-levels array? When there is a brightness array (and there is no interpolation) then it is indexed by brightness. The values in the array are not brightness (e.g. the controlable value describing the output of the hardware). The values in the table are merely the PWM duty cycle... Main difference is, with a correct table the brightness can use an appropriate logarithmic power scale (which matches how humans perceive brightness) instead of the linear scale provided by the PWM duty cycle. Daniel. Brightness and "index into the brightness-levels array" should be one and the same thing > > > > > > > > > > > > Daniel. > > > > Thanks an best regards, > > Flavio > > Thanks, > > Flavio
HI Daniel, ... > > ... > > > ... > > > > > > > +required: > > > > > > > + - compatible > > > > > > > + - reg > > > > > > > + - max-brightness > > > > > > > > > > > > Why is this mandatory? > > > > > > > > > > > > There's no point in setting max-brightness when running in I2C > > > > > > mode > > > > > > (max- brightness should default to 31 in that case). > > > > > > > > > > > > > > > > > > > + - default-brightness > > > > > > > > > > > > Again. I'm not clear why this needs to be mandatory. > > > > > > > > > > > > > > > > > > > > > > Ok, you are right, I'll remove max-brightness and > > > > > default-brightness from required properties list. I think to > > > > > change these properties, for the pwm dimming, into a clearer: > > > > > > > > > > - brightness-levels (uint32) > > > > > - default-brightness-levels (uint32). > > > > > > > > > > For example: > > > > > > > > > > brightness-levels: > > > > > description: > > > > > Number of brightness levels. The actual brightness > > > > > level (PWM duty cycle) will be interpolated from 0 to this value. > > > > > 0 means a 0% duty cycle (darkest/off), while the > > > > > brightness-levels > > > > represents > > > > > a 100% duty cycle (brightest). > > > > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > > > > > > > default-brightness-level: > > > > > description: > > > > > The default brightness level (from 0 to brightness-levels) > > > > > $ref: /schemas/types.yaml#/definitions/uint32 > > > > > > > > > > Example: > > > > > brightness-levels = <10>; > > > > > default-brightness-level = <6>; > > > > > > > > > > What do you think about this solution? > > > > > > > > If you want to introduce a brightness-levels property then I would > > > > expect it to be defined with the same meaning as pwm-backlight > > > > (it's not relevant to the bindings but ideally it would be > > > > implemented by refactoring and reusing the code from pwm_bl.c). > > > > > > ok, I'll use the brightness-levels property as used in pwm-backlight > > > > > > > > > > > Same with default-brightness-level although I'm not sure why one > > > > wouldn't just use default-brightness for new bindings (doesn't > > > > default-brightness-level simply do exactly the same thing as > > > > default- > > > brightness). > > > > > > ok for default-brightness instead of default-brightness-level > > > > Just a question: default-brightness-level is the index into the brightness- > levels array. > > But, if I use default-brightness instead of default-brightness-level, > > should I consider default-brightness also as an index into brightness-levels > array? > > Yes. > > > > Or, in this case, have the default-brightness to be equal to one of > > the values inside the brightness-levels array? > > When there is a brightness array (and there is no interpolation) then it is > indexed by brightness. The values in the array are not brightness (e.g. the > controlable value describing the output of the hardware). The values in the > table are merely the PWM duty cycle... ok > > Main difference is, with a correct table the brightness can use an appropriate > logarithmic power scale (which matches how humans perceive > brightness) instead of the linear scale provided by the PWM duty cycle. > > > Daniel. > > > Brightness and "index into the brightness-levels array" should be one and the > same thing ok, I'll use default-brightness, thanks for the explanations! > > > > > > > > > > > > > > > > > Daniel. > > > > > > Thanks an best regards, > > > Flavio > > > > Thanks, > > > > Flavio Flavio
diff --git a/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml new file mode 100644 index 000000000000..4191e33626f5 --- /dev/null +++ b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml @@ -0,0 +1,73 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/leds/backlight/mps,mp3309c.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: MPS MP3309C backlight + +maintainers: + - Flavio Suligoi <f.suligoi@asem.it> + +description: | + The Monolithic Power (MPS) MP3309C is a WLED step-up converter, featuring a + programmable switching frequency to optimize efficiency. + It supports two different dimming modes: + + - analog mode, via I2C commands (default) + - PWM controlled mode. + + The datasheet is available at: + https://www.monolithicpower.com/en/mp3309c.html + +allOf: + - $ref: common.yaml# + +properties: + compatible: + const: mps,mp3309c + + reg: + maxItems: 1 + + pwms: + description: if present, the backlight is controlled in PWM mode. + maxItems: 1 + + enable-gpios: + description: GPIO used to enable the backlight in "analog-i2c" dimming mode. + maxItems: 1 + + mps,overvoltage-protection-microvolt: + description: Overvoltage protection (13.5V, 24V or 35.5V). + enum: [ 13500000, 24000000, 35500000 ] + default: 35500000 + + mps,no-sync-mode: + description: disable synchronous rectification mode + type: boolean + +required: + - compatible + - reg + - max-brightness + - default-brightness + +unevaluatedProperties: false + +examples: + - | + i2c { + #address-cells = <1>; + #size-cells = <0>; + + /* Backlight with PWM control */ + backlight_pwm: backlight@17 { + compatible = "mps,mp3309c"; + reg = <0x17>; + pwms = <&pwm1 0 3333333 0>; /* 300 Hz --> (1/f) * 1*10^9 */ + max-brightness = <100>; + default-brightness = <80>; + mps,overvoltage-protection-microvolt = <24000000>; + }; + };