[PATCH v6 0/4] backlight: add new max25014 backlight driver

[PATCH v6 0/4] backlight: add new max25014 backlight driver

[Maud Spierings via B4 Relay]

The Maxim MAX25014 is an automotive grade backlight driver IC. Its
datasheet can be found at [1].

With its integrated boost controller, it can power 4 channels (led
strings) and has a number of different modes using pwm and or i2c.
Currently implemented is only i2c control.

link: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX25014.pdf [1]

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
Changes in v6:
- fixup changes in v4 where default brightness handling was changed but
  not noted
- remove leftover comment about initializing brightness
- use BIT definitions for fields in the DIAG register
- apply reverse christmas tree initialization of local variables
- remove !=0 from checks, just check if (ret)
- remove > 0 from checks, just check if (val)
- use dev_err_probe() more
- set enable gpio high in the get() instead of seperately calling set()
- change usleep_range() to fsleep()
- remove null checks when setting gpio value
- get regular regulator, not optional to avoid further NULL checks in
  case none is provided
- introduce max25014_initial_power_state() to check if the bootloader
  has already initialized the backlight and to correctly set props.power
- squash max25014_register_control() into max25014_update_status()
- in max25014_configure() perform extra checking on the DISABLE register
  now that the state from the bootloader is taken into account
- Link to v5: https://lore.kernel.org/r/20251107-max25014-v5-0-9a6aa57306bf@gocontroll.com

Changes in v5:
- moved comment about current functions of the driver to the actual
  comment section of the commit
- fixed the led@0 property, regex patternProperty is not needed as of
  now
- added extra clarification about the ISET field/register
- moved #address-cells and #size-cells to the correct location
- remove leftover default-brightness in backlight nodes
- Link to v4: https://lore.kernel.org/r/20251009-max25014-v4-0-6adb2a0aa35f@gocontroll.com

Changes in v4:
- remove setting default brightness, let backlight core take care of it
- use a led node to describe the backlight
- use led-sources to enable specific channels
- also wait 2ms when there is a supply but no enable
- change dev_warn() to dev_err() in error path in max25014_check_errors()
- set backlight_properties.scale to BACKLIGHT_SCALE_LINEAR
- rebase latest next
- add address-cells and size-cells to i2c4 in av101hdt-a10.dtso
- Link to v3: https://lore.kernel.org/r/20250911-max25014-v3-0-d03f4eba375e@gocontroll.com

Changes in v3:
- fixed commit message type intgrated -> integrated
- added maximum and description to maxim,iset-property
- dropped unused labels and pinctrl in bindings example
- put the compatible first in the bindings example and dts
- removed brackets around defines
- removed the leftover pdata struct field
- removed the initial_brightness struct field
- Link to v2: https://lore.kernel.org/r/20250819-max25014-v2-0-5fd7aeb141ea@gocontroll.com

Changes in v2:
- Remove leftover unused property from the bindings example
- Complete the bindings example with all properties
- Remove some double info from the maxim,iset property
- Remove platform_data header, fold its data into the max25014 struct
- Don't force defines to be unsigned
- Remove stray struct max25014 declaration
- Remove chipname and device from the max25014 struct
- Inline the max25014_backlight_register() and strings_mask() functions
- Remove CONFIG_OF ifdef
- Link to v1: https://lore.kernel.org/r/20250725-max25014-v1-0-0e8cce92078e@gocontroll.com

---
Maud Spierings (4):
      dt-bindings: backlight: Add max25014 support
      backlight: add max25014atg backlight
      arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight
      arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight

 .../bindings/leds/backlight/maxim,max25014.yaml    | 107 ++++++
 MAINTAINERS                                        |   6 +
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso |  30 ++
 ...x8p-ml81-moduline-display-106-av123z7m-n17.dtso |  25 +-
 drivers/video/backlight/Kconfig                    |   7 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/max25014.c                 | 419 +++++++++++++++++++++
 7 files changed, 594 insertions(+), 1 deletion(-)
---
base-commit: 9c0826a5d9aa4d52206dd89976858457a2a8a7ed
change-id: 20250626-max25014-4207591e1af5

Best regards,
-- 
Maud Spierings <maudspierings@gocontroll.com>

[PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
with integrated boost controller.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>

---

In the current implementation the control registers for channel 1,
control all channels. So only one led subnode with led-sources is
supported right now. If at some point the driver functionality is
expanded the bindings can be easily extended with it.
---
 .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
 MAINTAINERS                                        |   5 +
 2 files changed, 112 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
new file mode 100644
index 000000000000..e83723224b07
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
@@ -0,0 +1,107 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim max25014 backlight controller
+
+maintainers:
+  - Maud Spierings <maudspierings@gocontroll.com>
+
+properties:
+  compatible:
+    enum:
+      - maxim,max25014
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  enable-gpios:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  power-supply:
+    description: Regulator which controls the boost converter input rail.
+
+  pwms:
+    maxItems: 1
+
+  maxim,iset:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 15
+    default: 11
+    description:
+      Value of the ISET field in the ISET register. This controls the current
+      scale of the outputs, a higher number means more current.
+
+  led@0:
+    type: object
+    description: Properties for a string of connected LEDs.
+    $ref: common.yaml#
+
+    properties:
+      reg:
+        const: 0
+
+      led-sources:
+        allOf:
+          - minItems: 1
+            maxItems: 4
+            items:
+              minimum: 0
+              maximum: 3
+            default: [0, 1, 2, 3]
+
+      default-brightness:
+        minimum: 0
+        maximum: 100
+        default: 50
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        backlight@6f {
+            compatible = "maxim,max25014";
+            reg = <0x6f>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+            power-supply = <&reg_backlight>;
+            pwms = <&pwm1>;
+            maxim,iset = <7>;
+
+            led@0 {
+                reg = <0>;
+                led-sources = <0 1 2 3>;
+                default-brightness = <50>;
+            };
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 58c7e3f678d8..606ce086f758 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15261,6 +15261,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
 F:	drivers/media/i2c/max2175*
 F:	include/uapi/linux/max2175.h
 
+MAX25014 BACKLIGHT DRIVER
+M:	Maud Spierings <maudspierings@gocontroll.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
+
 MAX31335 RTC DRIVER
 M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
 L:	linux-rtc@vger.kernel.org

-- 
2.52.0

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Frank Li]

On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <maudspierings@gocontroll.com>
>
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
>
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>
> ---
>
> In the current implementation the control registers for channel 1,
> control all channels. So only one led subnode with led-sources is
> supported right now. If at some point the driver functionality is
> expanded the bindings can be easily extended with it.
> ---
>  .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>  MAINTAINERS                                        |   5 +
>  2 files changed, 112 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> new file mode 100644
> index 000000000000..e83723224b07
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> @@ -0,0 +1,107 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim max25014 backlight controller
> +
> +maintainers:
> +  - Maud Spierings <maudspierings@gocontroll.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - maxim,max25014
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +  enable-gpios:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  power-supply:
> +    description: Regulator which controls the boost converter input rail.
> +
> +  pwms:
> +    maxItems: 1
> +
> +  maxim,iset:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    maximum: 15
> +    default: 11
> +    description:
> +      Value of the ISET field in the ISET register. This controls the current
> +      scale of the outputs, a higher number means more current.
> +
> +  led@0:

define whole binding, allow 0-3. binding is not related with driver's
implement.

it'd better put unders leds.


> +    type: object
> +    description: Properties for a string of connected LEDs.
> +    $ref: common.yaml#
> +
> +    properties:
> +      reg:
> +        const: 0
> +
> +      led-sources:
> +        allOf:
> +          - minItems: 1
> +            maxItems: 4
> +            items:
> +              minimum: 0
> +              maximum: 3
> +            default: [0, 1, 2, 3]
> +
> +      default-brightness:
> +        minimum: 0
> +        maximum: 100
> +        default: 50
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false

unevaluatedProperties: false because ref to common.yaml

Frank

> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        backlight@6f {
> +            compatible = "maxim,max25014";
> +            reg = <0x6f>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> +            power-supply = <&reg_backlight>;
> +            pwms = <&pwm1>;
> +            maxim,iset = <7>;
> +
> +            led@0 {
> +                reg = <0>;
> +                led-sources = <0 1 2 3>;
> +                default-brightness = <50>;
> +            };
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 58c7e3f678d8..606ce086f758 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15261,6 +15261,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
>  F:	drivers/media/i2c/max2175*
>  F:	include/uapi/linux/max2175.h
>
> +MAX25014 BACKLIGHT DRIVER
> +M:	Maud Spierings <maudspierings@gocontroll.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> +
>  MAX31335 RTC DRIVER
>  M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
>  L:	linux-rtc@vger.kernel.org
>
> --
> 2.52.0
>
>

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings]

On 12/1/25 17:52, Frank Li wrote:
> On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
>> From: Maud Spierings <maudspierings@gocontroll.com>
>>
>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>> with integrated boost controller.
>>
>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>>
>> ---
>>
>> In the current implementation the control registers for channel 1,
>> control all channels. So only one led subnode with led-sources is
>> supported right now. If at some point the driver functionality is
>> expanded the bindings can be easily extended with it.
>> ---
>>   .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>>   MAINTAINERS                                        |   5 +
>>   2 files changed, 112 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> new file mode 100644
>> index 000000000000..e83723224b07
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> @@ -0,0 +1,107 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Maxim max25014 backlight controller
>> +
>> +maintainers:
>> +  - Maud Spierings <maudspierings@gocontroll.com>
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - maxim,max25014
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  "#address-cells":
>> +    const: 1
>> +
>> +  "#size-cells":
>> +    const: 0
>> +
>> +  enable-gpios:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  power-supply:
>> +    description: Regulator which controls the boost converter input rail.
>> +
>> +  pwms:
>> +    maxItems: 1
>> +
>> +  maxim,iset:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    maximum: 15
>> +    default: 11
>> +    description:
>> +      Value of the ISET field in the ISET register. This controls the current
>> +      scale of the outputs, a higher number means more current.
>> +
>> +  led@0:
> 
> define whole binding, allow 0-3. binding is not related with driver's
> implement.
> 
> it'd better put unders leds.
>

so like:

backlight: backlight@6f {
	compatible = "maxim,max25014";
	reg = <0x6f>;
	enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_backlight>;
	maxim,iset = <7>;

	leds {
		#address-cells = <1>;
		#size-cells = <0>;

		led@0 {
			reg = <0>;
			led-sources = <0 1 2>;
			default-brightness = <50>;
		};

		optional led@#....
	};
};

right?

Kind regards,
Maud

> 
>> +    type: object
>> +    description: Properties for a string of connected LEDs.
>> +    $ref: common.yaml#
>> +
>> +    properties:
>> +      reg:
>> +        const: 0
>> +
>> +      led-sources:
>> +        allOf:
>> +          - minItems: 1
>> +            maxItems: 4
>> +            items:
>> +              minimum: 0
>> +              maximum: 3
>> +            default: [0, 1, 2, 3]
>> +
>> +      default-brightness:
>> +        minimum: 0
>> +        maximum: 100
>> +        default: 50
>> +
>> +    required:
>> +      - reg
>> +
>> +    additionalProperties: false
> 
> unevaluatedProperties: false because ref to common.yaml
> 
> Frank
> 

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Frank Li]

On Tue, Dec 02, 2025 at 08:46:21AM +0100, Maud Spierings wrote:
> On 12/1/25 17:52, Frank Li wrote:
> > On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
> > > From: Maud Spierings <maudspierings@gocontroll.com>
> > >
> > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> > > with integrated boost controller.
> > >
> > > Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> > >
> > > ---
> > >
> > > In the current implementation the control registers for channel 1,
> > > control all channels. So only one led subnode with led-sources is
> > > supported right now. If at some point the driver functionality is
> > > expanded the bindings can be easily extended with it.
> > > ---
> > >   .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
> > >   MAINTAINERS                                        |   5 +
> > >   2 files changed, 112 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > new file mode 100644
> > > index 000000000000..e83723224b07
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > @@ -0,0 +1,107 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Maxim max25014 backlight controller
> > > +
> > > +maintainers:
> > > +  - Maud Spierings <maudspierings@gocontroll.com>
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - maxim,max25014
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  "#address-cells":
> > > +    const: 1
> > > +
> > > +  "#size-cells":
> > > +    const: 0
> > > +
> > > +  enable-gpios:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  power-supply:
> > > +    description: Regulator which controls the boost converter input rail.
> > > +
> > > +  pwms:
> > > +    maxItems: 1
> > > +
> > > +  maxim,iset:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    maximum: 15
> > > +    default: 11
> > > +    description:
> > > +      Value of the ISET field in the ISET register. This controls the current
> > > +      scale of the outputs, a higher number means more current.
> > > +
> > > +  led@0:
> >
> > define whole binding, allow 0-3. binding is not related with driver's
> > implement.
> >
> > it'd better put unders leds.
> >
>
> so like:
>
> backlight: backlight@6f {
> 	compatible = "maxim,max25014";
> 	reg = <0x6f>;
> 	enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> 	pinctrl-names = "default";
> 	pinctrl-0 = <&pinctrl_backlight>;
> 	maxim,iset = <7>;
>
> 	leds {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
>
> 		led@0 {
> 			reg = <0>;
> 			led-sources = <0 1 2>;
> 			default-brightness = <50>;
> 		};
>
> 		optional led@#....
> 	};
> };
>
> right?

yes.

>
> Kind regards,
> Maud
>
> >
> > > +    type: object
> > > +    description: Properties for a string of connected LEDs.
> > > +    $ref: common.yaml#
> > > +
> > > +    properties:
> > > +      reg:
> > > +        const: 0
> > > +
> > > +      led-sources:
> > > +        allOf:
> > > +          - minItems: 1
> > > +            maxItems: 4
> > > +            items:
> > > +              minimum: 0
> > > +              maximum: 3
> > > +            default: [0, 1, 2, 3]
> > > +
> > > +      default-brightness:
> > > +        minimum: 0
> > > +        maximum: 100
> > > +        default: 50
> > > +
> > > +    required:
> > > +      - reg
> > > +
> > > +    additionalProperties: false
> >
> > unevaluatedProperties: false because ref to common.yaml
> >
> > Frank
> >
>
>

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings]

On 12/2/25 15:53, Frank Li wrote:
> On Tue, Dec 02, 2025 at 08:46:21AM +0100, Maud Spierings wrote:
>> On 12/1/25 17:52, Frank Li wrote:
>>> On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
>>>> From: Maud Spierings <maudspierings@gocontroll.com>
>>>>
>>>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>>>> with integrated boost controller.
>>>>
>>>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>>>>
>>>> ---
>>>>
>>>> In the current implementation the control registers for channel 1,
>>>> control all channels. So only one led subnode with led-sources is
>>>> supported right now. If at some point the driver functionality is
>>>> expanded the bindings can be easily extended with it.
>>>> ---
>>>>    .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>>>>    MAINTAINERS                                        |   5 +
>>>>    2 files changed, 112 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>>>> new file mode 100644
>>>> index 000000000000..e83723224b07
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>>>> @@ -0,0 +1,107 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: Maxim max25014 backlight controller
>>>> +
>>>> +maintainers:
>>>> +  - Maud Spierings <maudspierings@gocontroll.com>
>>>> +
>>>> +properties:
>>>> +  compatible:
>>>> +    enum:
>>>> +      - maxim,max25014
>>>> +
>>>> +  reg:
>>>> +    maxItems: 1
>>>> +
>>>> +  "#address-cells":
>>>> +    const: 1
>>>> +
>>>> +  "#size-cells":
>>>> +    const: 0
>>>> +
>>>> +  enable-gpios:
>>>> +    maxItems: 1
>>>> +
>>>> +  interrupts:
>>>> +    maxItems: 1
>>>> +
>>>> +  power-supply:
>>>> +    description: Regulator which controls the boost converter input rail.
>>>> +
>>>> +  pwms:
>>>> +    maxItems: 1
>>>> +
>>>> +  maxim,iset:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    maximum: 15
>>>> +    default: 11
>>>> +    description:
>>>> +      Value of the ISET field in the ISET register. This controls the current
>>>> +      scale of the outputs, a higher number means more current.
>>>> +
>>>> +  led@0:
>>>
>>> define whole binding, allow 0-3. binding is not related with driver's
>>> implement.
>>>
>>> it'd better put unders leds.
>>>
>>
>> so like:
>>
>> backlight: backlight@6f {
>> 	compatible = "maxim,max25014";
>> 	reg = <0x6f>;
>> 	enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
>> 	pinctrl-names = "default";
>> 	pinctrl-0 = <&pinctrl_backlight>;
>> 	maxim,iset = <7>;
>>
>> 	leds {
>> 		#address-cells = <1>;
>> 		#size-cells = <0>;
>>
>> 		led@0 {
>> 			reg = <0>;
>> 			led-sources = <0 1 2>;
>> 			default-brightness = <50>;
>> 		};
>>
>> 		optional led@#....
>> 	};
>> };
>>
>> right?
> 
> yes.
> 

I am feeling a bit weird about these led sub nodes, because it is not 
programmed as a led driver, it is programmed as a backlight. I am trying 
to figure out how this would be used later when the led strings are 
individually controllable.

it isn't possible to link the seperate strings to different displays 
because it is only one backlight device, so I don't seen any reason why 
it would ever be used in another way than what it is now, were all 
strings are programmed by one register.

The only way I can make sense of it is if instead I program this device 
as a led driver and then use the led_bl driver as the actual backlight.

Thats a pretty big step in a different direction, but then the led 
subnodes at least can be properly used I feel.

Kind regards,
Maud

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Rob Herring]

On Mon, Dec 08, 2025 at 02:56:50PM +0100, Maud Spierings wrote:
> On 12/2/25 15:53, Frank Li wrote:
> > On Tue, Dec 02, 2025 at 08:46:21AM +0100, Maud Spierings wrote:
> > > On 12/1/25 17:52, Frank Li wrote:
> > > > On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
> > > > > From: Maud Spierings <maudspierings@gocontroll.com>
> > > > > 
> > > > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> > > > > with integrated boost controller.
> > > > > 
> > > > > Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> > > > > 
> > > > > ---
> > > > > 
> > > > > In the current implementation the control registers for channel 1,
> > > > > control all channels. So only one led subnode with led-sources is
> > > > > supported right now. If at some point the driver functionality is
> > > > > expanded the bindings can be easily extended with it.
> > > > > ---
> > > > >    .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
> > > > >    MAINTAINERS                                        |   5 +
> > > > >    2 files changed, 112 insertions(+)
> > > > > 
> > > > > diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > > > new file mode 100644
> > > > > index 000000000000..e83723224b07
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > > > @@ -0,0 +1,107 @@
> > > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > > +%YAML 1.2
> > > > > +---
> > > > > +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > > +
> > > > > +title: Maxim max25014 backlight controller
> > > > > +
> > > > > +maintainers:
> > > > > +  - Maud Spierings <maudspierings@gocontroll.com>
> > > > > +
> > > > > +properties:
> > > > > +  compatible:
> > > > > +    enum:
> > > > > +      - maxim,max25014
> > > > > +
> > > > > +  reg:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  "#address-cells":
> > > > > +    const: 1
> > > > > +
> > > > > +  "#size-cells":
> > > > > +    const: 0
> > > > > +
> > > > > +  enable-gpios:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  interrupts:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  power-supply:
> > > > > +    description: Regulator which controls the boost converter input rail.
> > > > > +
> > > > > +  pwms:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  maxim,iset:
> > > > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > > > +    maximum: 15
> > > > > +    default: 11
> > > > > +    description:
> > > > > +      Value of the ISET field in the ISET register. This controls the current
> > > > > +      scale of the outputs, a higher number means more current.
> > > > > +
> > > > > +  led@0:
> > > > 
> > > > define whole binding, allow 0-3. binding is not related with driver's
> > > > implement.
> > > > 
> > > > it'd better put unders leds.
> > > > 
> > > 
> > > so like:
> > > 
> > > backlight: backlight@6f {
> > > 	compatible = "maxim,max25014";
> > > 	reg = <0x6f>;
> > > 	enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> > > 	pinctrl-names = "default";
> > > 	pinctrl-0 = <&pinctrl_backlight>;
> > > 	maxim,iset = <7>;
> > > 
> > > 	leds {
> > > 		#address-cells = <1>;
> > > 		#size-cells = <0>;
> > > 
> > > 		led@0 {
> > > 			reg = <0>;
> > > 			led-sources = <0 1 2>;
> > > 			default-brightness = <50>;
> > > 		};
> > > 
> > > 		optional led@#....
> > > 	};
> > > };
> > > 
> > > right?
> > 
> > yes.
> > 
> 
> I am feeling a bit weird about these led sub nodes, because it is not
> programmed as a led driver, it is programmed as a backlight. I am trying to
> figure out how this would be used later when the led strings are
> individually controllable.
> 
> it isn't possible to link the seperate strings to different displays because
> it is only one backlight device, so I don't seen any reason why it would
> ever be used in another way than what it is now, were all strings are
> programmed by one register.
> 
> The only way I can make sense of it is if instead I program this device as a
> led driver and then use the led_bl driver as the actual backlight.
> 
> Thats a pretty big step in a different direction, but then the led subnodes
> at least can be properly used I feel.

If you don't have any use for anything other than driving a single 
backlight, then I'd just drop the led nodes completely.

Rob

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings]

On 12/9/25 20:07, Rob Herring wrote:
> On Mon, Dec 08, 2025 at 02:56:50PM +0100, Maud Spierings wrote:
>> On 12/2/25 15:53, Frank Li wrote:
>>> On Tue, Dec 02, 2025 at 08:46:21AM +0100, Maud Spierings wrote:
>>>> On 12/1/25 17:52, Frank Li wrote:
>>>>> On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
>>>>>> From: Maud Spierings <maudspierings@gocontroll.com>
>>>>>>
>>>>>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>>>>>> with integrated boost controller.
>>>>>>
>>>>>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>>>>>>
>>>>>> ---
>>>>>>
>>>>>> In the current implementation the control registers for channel 1,
>>>>>> control all channels. So only one led subnode with led-sources is
>>>>>> supported right now. If at some point the driver functionality is
>>>>>> expanded the bindings can be easily extended with it.
>>>>>> ---
>>>>>>     .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>>>>>>     MAINTAINERS                                        |   5 +
>>>>>>     2 files changed, 112 insertions(+)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>>>>>> new file mode 100644
>>>>>> index 000000000000..e83723224b07
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>>>>>> @@ -0,0 +1,107 @@
>>>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>>>>> +%YAML 1.2
>>>>>> +---
>>>>>> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>>> +
>>>>>> +title: Maxim max25014 backlight controller
>>>>>> +
>>>>>> +maintainers:
>>>>>> +  - Maud Spierings <maudspierings@gocontroll.com>
>>>>>> +
>>>>>> +properties:
>>>>>> +  compatible:
>>>>>> +    enum:
>>>>>> +      - maxim,max25014
>>>>>> +
>>>>>> +  reg:
>>>>>> +    maxItems: 1
>>>>>> +
>>>>>> +  "#address-cells":
>>>>>> +    const: 1
>>>>>> +
>>>>>> +  "#size-cells":
>>>>>> +    const: 0
>>>>>> +
>>>>>> +  enable-gpios:
>>>>>> +    maxItems: 1
>>>>>> +
>>>>>> +  interrupts:
>>>>>> +    maxItems: 1
>>>>>> +
>>>>>> +  power-supply:
>>>>>> +    description: Regulator which controls the boost converter input rail.
>>>>>> +
>>>>>> +  pwms:
>>>>>> +    maxItems: 1
>>>>>> +
>>>>>> +  maxim,iset:
>>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>>> +    maximum: 15
>>>>>> +    default: 11
>>>>>> +    description:
>>>>>> +      Value of the ISET field in the ISET register. This controls the current
>>>>>> +      scale of the outputs, a higher number means more current.
>>>>>> +
>>>>>> +  led@0:
>>>>>
>>>>> define whole binding, allow 0-3. binding is not related with driver's
>>>>> implement.
>>>>>
>>>>> it'd better put unders leds.
>>>>>
>>>>
>>>> so like:
>>>>
>>>> backlight: backlight@6f {
>>>> 	compatible = "maxim,max25014";
>>>> 	reg = <0x6f>;
>>>> 	enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
>>>> 	pinctrl-names = "default";
>>>> 	pinctrl-0 = <&pinctrl_backlight>;
>>>> 	maxim,iset = <7>;
>>>>
>>>> 	leds {
>>>> 		#address-cells = <1>;
>>>> 		#size-cells = <0>;
>>>>
>>>> 		led@0 {
>>>> 			reg = <0>;
>>>> 			led-sources = <0 1 2>;
>>>> 			default-brightness = <50>;
>>>> 		};
>>>>
>>>> 		optional led@#....
>>>> 	};
>>>> };
>>>>
>>>> right?
>>>
>>> yes.
>>>
>>
>> I am feeling a bit weird about these led sub nodes, because it is not
>> programmed as a led driver, it is programmed as a backlight. I am trying to
>> figure out how this would be used later when the led strings are
>> individually controllable.
>>
>> it isn't possible to link the seperate strings to different displays because
>> it is only one backlight device, so I don't seen any reason why it would
>> ever be used in another way than what it is now, were all strings are
>> programmed by one register.
>>
>> The only way I can make sense of it is if instead I program this device as a
>> led driver and then use the led_bl driver as the actual backlight.
>>
>> Thats a pretty big step in a different direction, but then the led subnodes
>> at least can be properly used I feel.
> 
> If you don't have any use for anything other than driving a single
> backlight, then I'd just drop the led nodes completely.

Theoretically with how the registers are laid out, it should be able to 
control 4 led strings individually. But as I said when I configure led 
string 1 it will also affect all the others seemingly. I am not sure if 
with some other configuration you can indeed do individual control.

Before I start converting stuff back to how it was several versions ago. 
Frank, do you agree with removing the led nodes in this case? I don't 
want to get stuck between two different paths.

Kind regards,
Maud

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Rob Herring]

On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings wrote:
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
>
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> 
> ---
> 
> In the current implementation the control registers for channel 1,
> control all channels. So only one led subnode with led-sources is
> supported right now. If at some point the driver functionality is
> expanded the bindings can be easily extended with it.

What's the relationship between the LEDs and backlight? It's a backlight 
plus LEDs or just 4 identical channels.

> 
> ---
>  .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>  MAINTAINERS                                        |   5 +
>  2 files changed, 112 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> new file mode 100644
> index 000000000000..e83723224b07
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> @@ -0,0 +1,107 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim max25014 backlight controller
> +
> +maintainers:
> +  - Maud Spierings <maudspierings@gocontroll.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - maxim,max25014
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +  enable-gpios:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  power-supply:
> +    description: Regulator which controls the boost converter input rail.
> +
> +  pwms:
> +    maxItems: 1
> +
> +  maxim,iset:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    maximum: 15
> +    default: 11
> +    description:
> +      Value of the ISET field in the ISET register. This controls the current
> +      scale of the outputs, a higher number means more current.

We have properties for setting the current (in uA). That can't work 
here?

> +
> +  led@0:
> +    type: object
> +    description: Properties for a string of connected LEDs.
> +    $ref: common.yaml#
> +
> +    properties:
> +      reg:
> +        const: 0
> +
> +      led-sources:
> +        allOf:
> +          - minItems: 1
> +            maxItems: 4
> +            items:
> +              minimum: 0
> +              maximum: 3
> +            default: [0, 1, 2, 3]
> +
> +      default-brightness:
> +        minimum: 0
> +        maximum: 100
> +        default: 50
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        backlight@6f {
> +            compatible = "maxim,max25014";
> +            reg = <0x6f>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> +            power-supply = <&reg_backlight>;
> +            pwms = <&pwm1>;
> +            maxim,iset = <7>;
> +
> +            led@0 {
> +                reg = <0>;
> +                led-sources = <0 1 2 3>;
> +                default-brightness = <50>;
> +            };
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 58c7e3f678d8..606ce086f758 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15261,6 +15261,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
>  F:	drivers/media/i2c/max2175*
>  F:	include/uapi/linux/max2175.h
>  
> +MAX25014 BACKLIGHT DRIVER
> +M:	Maud Spierings <maudspierings@gocontroll.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> +
>  MAX31335 RTC DRIVER
>  M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
>  L:	linux-rtc@vger.kernel.org
> 
> -- 
> 2.52.0
> 

Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings]

Thanks for the review.

On 12/5/25 16:07, Rob Herring wrote:
> On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings wrote:
>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>> with integrated boost controller.
>>
>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>>
>> ---
>>
>> In the current implementation the control registers for channel 1,
>> control all channels. So only one led subnode with led-sources is
>> supported right now. If at some point the driver functionality is
>> expanded the bindings can be easily extended with it.
> 
> What's the relationship between the LEDs and backlight? It's a backlight
> plus LEDs or just 4 identical channels.

it is just 4 identical channels, represented as leds, or in this case 1 
led. I still feel a bit weird about this representation when there is 
also led-backlight. But it was requested to map it in this way.

>>
>> ---
>>   .../bindings/leds/backlight/maxim,max25014.yaml    | 107 +++++++++++++++++++++
>>   MAINTAINERS                                        |   5 +
>>   2 files changed, 112 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> new file mode 100644
>> index 000000000000..e83723224b07
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> @@ -0,0 +1,107 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Maxim max25014 backlight controller
>> +
>> +maintainers:
>> +  - Maud Spierings <maudspierings@gocontroll.com>
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - maxim,max25014
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  "#address-cells":
>> +    const: 1
>> +
>> +  "#size-cells":
>> +    const: 0
>> +
>> +  enable-gpios:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  power-supply:
>> +    description: Regulator which controls the boost converter input rail.
>> +
>> +  pwms:
>> +    maxItems: 1
>> +
>> +  maxim,iset:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    maximum: 15
>> +    default: 11
>> +    description:
>> +      Value of the ISET field in the ISET register. This controls the current
>> +      scale of the outputs, a higher number means more current.
> 
> We have properties for setting the current (in uA). That can't work
> here?

please refer to [1] and [2].

Link: 
https://lore.kernel.org/all/5c5cf363-db5c-4d0b-902f-97c6ef06c08f@gocontroll.com/ 
[1]

Link: 
https://lore.kernel.org/all/20251009-overjoyed-unpopular-54f69e9bd82c@spud/ 
[2]

kind regards,
Maud

[PATCH v6 2/4] backlight: add max25014atg backlight

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
with integrated boost controller.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 MAINTAINERS                        |   1 +
 drivers/video/backlight/Kconfig    |   7 +
 drivers/video/backlight/Makefile   |   1 +
 drivers/video/backlight/max25014.c | 419 +++++++++++++++++++++++++++++++++++++
 4 files changed, 428 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 606ce086f758..d082d3f8cfae 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15265,6 +15265,7 @@ MAX25014 BACKLIGHT DRIVER
 M:	Maud Spierings <maudspierings@gocontroll.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
+F:	drivers/video/backlight/max25014.c
 
 MAX31335 RTC DRIVER
 M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index d9374d208cee..d3bb6ccd4185 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -262,6 +262,13 @@ config BACKLIGHT_DA9052
 	help
 	  Enable the Backlight Driver for DA9052-BC and DA9053-AA/Bx PMICs.
 
+config BACKLIGHT_MAX25014
+	tristate "Backlight driver for the Maxim MAX25014 chip"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you are using a MAX25014 chip as a backlight driver say Y to enable it.
+
 config BACKLIGHT_MAX8925
 	tristate "Backlight driver for MAX8925"
 	depends on MFD_MAX8925
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index dfbb169bf6ea..1170d9ec40b8 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_BACKLIGHT_LOCOMO)		+= locomolcd.o
 obj-$(CONFIG_BACKLIGHT_LP855X)		+= lp855x_bl.o
 obj-$(CONFIG_BACKLIGHT_LP8788)		+= lp8788_bl.o
 obj-$(CONFIG_BACKLIGHT_LV5207LP)	+= lv5207lp.o
+obj-$(CONFIG_BACKLIGHT_MAX25014)	+= max25014.o
 obj-$(CONFIG_BACKLIGHT_MAX8925)		+= max8925_bl.o
 obj-$(CONFIG_BACKLIGHT_MP3309C)		+= mp3309c.o
 obj-$(CONFIG_BACKLIGHT_MT6370)		+= mt6370-backlight.o
diff --git a/drivers/video/backlight/max25014.c b/drivers/video/backlight/max25014.c
new file mode 100644
index 000000000000..7000225752c3
--- /dev/null
+++ b/drivers/video/backlight/max25014.c
@@ -0,0 +1,419 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Backlight driver for Maxim MAX25014
+ *
+ * Copyright (C) 2025 GOcontroll B.V.
+ * Author: Maud Spierings <maudspierings@gocontroll.com>
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define MAX25014_ISET_DEFAULT_100 11
+#define MAX_BRIGHTNESS            100
+#define MIN_BRIGHTNESS            0
+#define TON_MAX                   130720 /* @153Hz */
+#define TON_STEP                  1307 /* @153Hz */
+#define TON_MIN                   0
+
+#define MAX25014_DEV_ID           0x00
+#define MAX25014_REV_ID           0x01
+#define MAX25014_ISET             0x02
+#define MAX25014_IMODE            0x03
+#define MAX25014_TON1H            0x04
+#define MAX25014_TON1L            0x05
+#define MAX25014_TON2H            0x06
+#define MAX25014_TON2L            0x07
+#define MAX25014_TON3H            0x08
+#define MAX25014_TON3L            0x09
+#define MAX25014_TON4H            0x0A
+#define MAX25014_TON4L            0x0B
+#define MAX25014_TON_1_4_LSB      0x0C
+#define MAX25014_SETTING          0x12
+#define MAX25014_DISABLE          0x13
+#define MAX25014_BSTMON           0x14
+#define MAX25014_IOUT1            0x15
+#define MAX25014_IOUT2            0x16
+#define MAX25014_IOUT3            0x17
+#define MAX25014_IOUT4            0x18
+#define MAX25014_OPEN             0x1B
+#define MAX25014_SHORT_GND        0x1C
+#define MAX25014_SHORT_LED        0x1D
+#define MAX25014_MASK             0x1E
+#define MAX25014_DIAG             0x1F
+
+#define MAX25014_ISET_ENA         BIT(5)
+#define MAX25014_ISET_PSEN        BIT(4)
+#define MAX25014_IMODE_HDIM       BIT(2)
+#define MAX25014_SETTING_FPWM     GENMASK(6, 4)
+#define MAX25014_DISABLE_DIS_MASK GENMASK(3, 0)
+#define MAX25014_DIAG_OT          BIT(0)
+#define MAX25014_DIAG_OTW         BIT(1)
+#define MAX25014_DIAG_HW_RST      BIT(2)
+#define MAX25014_DIAG_BSTOV       BIT(3)
+#define MAX25014_DIAG_BSTUV       BIT(4)
+#define MAX25014_DIAG_IREFOOR     BIT(5)
+
+struct max25014 {
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct regmap *regmap;
+	struct gpio_desc *enable;
+	struct regulator *vin; /* regulator for boost converter Vin rail */
+	uint32_t iset;
+	uint8_t strings_mask;
+};
+
+static const struct regmap_config max25014_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MAX25014_DIAG,
+};
+
+static int max25014_initial_power_state(struct max25014 *maxim)
+{
+	uint32_t val;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_ISET, &val);
+	if (ret)
+		return ret;
+
+	return val & MAX25014_ISET_ENA ? BACKLIGHT_POWER_ON : BACKLIGHT_POWER_OFF;
+}
+
+static int max25014_check_errors(struct max25014 *maxim)
+{
+	uint32_t val;
+	uint8_t i;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		dev_err(&maxim->client->dev, "Open led strings detected on:\n");
+		for (i = 0; i < 4; i++) {
+			if (val & 1 << i)
+				dev_err(&maxim->client->dev, "string %d\n", i + 1);
+		}
+		return -EIO;
+	}
+
+	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		dev_err(&maxim->client->dev, "Short to ground detected on:\n");
+		for (i = 0; i < 4; i++) {
+			if (val & 1 << i)
+				dev_err(&maxim->client->dev, "string %d\n", i + 1);
+		}
+		return -EIO;
+	}
+
+	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		dev_err(&maxim->client->dev, "Shorted led detected on:\n");
+		for (i = 0; i < 4; i++) {
+			if (val & 1 << i)
+				dev_err(&maxim->client->dev, "string %d\n", i + 1);
+		}
+		return -EIO;
+	}
+
+	ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val);
+	if (ret)
+		return ret;
+	/*
+	 * The HW_RST bit always starts at 1 after power up.
+	 * It is reset on first read, does not indicate an error.
+	 */
+	if (val && val != MAX25014_DIAG_HW_RST) {
+		if (val & MAX25014_DIAG_OT)
+			dev_err(&maxim->client->dev,
+				"Overtemperature shutdown\n");
+		if (val & MAX25014_DIAG_OTW)
+			dev_err(&maxim->client->dev,
+				 "Chip is getting too hot (>125C)\n");
+		if (val & MAX25014_DIAG_BSTOV)
+			dev_err(&maxim->client->dev,
+				"Boost converter overvoltage\n");
+		if (val & MAX25014_DIAG_BSTUV)
+			dev_err(&maxim->client->dev,
+				"Boost converter undervoltage\n");
+		if (val & MAX25014_DIAG_IREFOOR)
+			dev_err(&maxim->client->dev, "IREF out of range\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * 1. disable unused strings
+ * 2. set dim mode
+ * 3. set setting register
+ * 4. enable the backlight
+ */
+static int max25014_configure(struct max25014 *maxim, int initial_state)
+{
+	uint32_t val;
+	int ret;
+
+	/*
+	 * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
+	 * it needs to be changed at all to prevent the backlight flashing when
+	 * it is configured correctly by the bootloader
+	 */
+	ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
+	if (ret)
+		return ret;
+
+	if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
+		if (initial_state == BACKLIGHT_POWER_ON) {
+			ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
+			if (ret)
+				return ret;
+		}
+		ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_SETTING,
+			   val & ~MAX25014_SETTING_FPWM);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_ISET,
+			   maxim->iset | MAX25014_ISET_ENA |
+			   MAX25014_ISET_PSEN);
+	return ret;
+}
+
+static int max25014_update_status(struct backlight_device *bl_dev)
+{
+	struct max25014 *maxim = bl_get_data(bl_dev);
+	uint32_t reg;
+	int ret;
+
+	if (backlight_is_blank(maxim->bl))
+		bl_dev->props.brightness = 0;
+
+	reg  = TON_STEP * bl_dev->props.brightness;
+
+	/*
+	 * 18 bit number lowest, 2 bits in first register,
+	 * next lowest 8 in the L register, next 8 in the H register
+	 * Seemingly setting the strength of only one string controls all of
+	 * them, individual settings don't affect the outcome.
+	 */
+
+	ret = regmap_write(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
+	if (ret != 0)
+		return ret;
+	ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
+	if (ret != 0)
+		return ret;
+	return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
+}
+
+static const struct backlight_ops max25014_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = max25014_update_status,
+};
+
+static int max25014_parse_dt(struct max25014 *maxim,
+			     uint32_t *initial_brightness)
+{
+	struct device *dev = &maxim->client->dev;
+	struct device_node *node = dev->of_node;
+	struct fwnode_handle *child;
+	uint32_t strings[4];
+	int res, i;
+
+	if (!node)
+		return dev_err_probe(dev, -EINVAL, "no platform data\n");
+
+	child = device_get_next_child_node(dev, NULL);
+	if (child) {
+		res = fwnode_property_count_u32(child, "led-sources");
+		if (res > 0) {
+			fwnode_property_read_u32_array(child, "led-sources",
+						       strings, res);
+
+			/* set all strings as disabled, then enable those in led-sources*/
+			maxim->strings_mask = 0xf;
+			for (i = 0; i < res; i++) {
+				if (strings[i] <= 4)
+					maxim->strings_mask &= ~BIT(strings[i]);
+			}
+		}
+
+		fwnode_property_read_u32(child, "default-brightness",
+					 initial_brightness);
+
+		fwnode_handle_put(child);
+	}
+
+	maxim->iset = MAX25014_ISET_DEFAULT_100;
+	of_property_read_u32(node, "maxim,iset", &maxim->iset);
+
+	if (maxim->iset > 15)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid iset, should be a value from 0-15, entered was %d\n",
+				     maxim->iset);
+
+	if (*initial_brightness > 100)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid initial brightness, should be a value from 0-100, entered was %d\n",
+				     *initial_brightness);
+
+	return 0;
+}
+
+static int max25014_probe(struct i2c_client *cl)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
+	struct backlight_properties props;
+	uint32_t initial_brightness = 50;
+	struct backlight_device *bl;
+	struct max25014 *maxim;
+	int ret;
+
+	maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL);
+	if (!maxim)
+		return -ENOMEM;
+
+	maxim->client = cl;
+
+	ret = max25014_parse_dt(maxim, &initial_brightness);
+	if (ret)
+		return ret;
+
+	maxim->vin = devm_regulator_get(&maxim->client->dev, "power");
+	if (IS_ERR(maxim->vin)) {
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->vin),
+				     "failed to get power-supply");
+	}
+
+	ret = regulator_enable(maxim->vin);
+	if (ret)
+		return dev_err_probe(&maxim->client->dev, ret,
+			"failed to enable power-supply\n");
+
+	maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
+						GPIOD_OUT_HIGH);
+	if (IS_ERR(maxim->enable)) {
+		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
+				    "failed to get enable gpio\n");
+		goto disable_vin;
+	}
+
+	/* Datasheet Electrical Characteristics tSTARTUP 2ms */
+	fsleep(2000);
+
+	maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
+	if (IS_ERR(maxim->regmap)) {
+		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
+			"failed to initialize the i2c regmap\n");
+		goto disable_full;
+	}
+
+	i2c_set_clientdata(cl, maxim);
+
+	ret = max25014_check_errors(maxim);
+	if (ret) { /* error is already reported in the above function */
+		goto disable_full;
+	}
+
+	ret = max25014_initial_power_state(maxim);
+	if (ret < 0) {
+		dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n");
+		goto disable_full;
+	}
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+	props.brightness = initial_brightness;
+	props.scale = BACKLIGHT_SCALE_LINEAR;
+	props.power = ret;
+
+	ret = max25014_configure(maxim, ret);
+	if (ret) {
+		dev_err_probe(&maxim->client->dev, ret, "device config error");
+		goto disable_full;
+	}
+
+	bl = devm_backlight_device_register(&maxim->client->dev, id->name,
+					    &maxim->client->dev, maxim,
+					    &max25014_bl_ops, &props);
+	if (IS_ERR(bl)) {
+		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
+				    "failed to register backlight\n");
+		goto disable_full;
+	}
+
+	maxim->bl = bl;
+
+	backlight_update_status(maxim->bl);
+
+	return 0;
+
+disable_full:
+	gpiod_set_value_cansleep(maxim->enable, 0);
+disable_vin:
+	regulator_disable(maxim->vin);
+	return ret;
+}
+
+static void max25014_remove(struct i2c_client *cl)
+{
+	struct max25014 *maxim = i2c_get_clientdata(cl);
+
+	maxim->bl->props.brightness = 0;
+	max25014_update_status(maxim->bl);
+	gpiod_set_value_cansleep(maxim->enable, 0);
+	regulator_disable(maxim->vin);
+}
+
+static const struct of_device_id max25014_dt_ids[] = {
+	{ .compatible = "maxim,max25014", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max25014_dt_ids);
+
+static const struct i2c_device_id max25014_ids[] = {
+	{ "max25014" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max25014_ids);
+
+static struct i2c_driver max25014_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = of_match_ptr(max25014_dt_ids),
+	},
+	.probe = max25014_probe,
+	.remove = max25014_remove,
+	.id_table = max25014_ids,
+};
+module_i2c_driver(max25014_driver);
+
+MODULE_DESCRIPTION("Maxim MAX25014 backlight driver");
+MODULE_AUTHOR("Maud Spierings <maudspierings@gocontroll.com>");
+MODULE_LICENSE("GPL");

-- 
2.52.0

Re: [PATCH v6 2/4] backlight: add max25014atg backlight

[Daniel Thompson]

On Mon, Dec 01, 2025 at 12:53:21PM +0100, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <maudspierings@gocontroll.com>
>
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
>
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>

> <snip>

> +static int max25014_check_errors(struct max25014 *maxim)
> +{
> +	uint32_t val;
> +	uint8_t i;
> +	int ret;
> +
> +	ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
> +	if (ret)
> +		return ret;
> +	if (val) {
> +		dev_err(&maxim->client->dev, "Open led strings detected on:\n");
> +		for (i = 0; i < 4; i++) {
> +			if (val & 1 << i)
> +				dev_err(&maxim->client->dev, "string %d\n", i + 1);
> +		}
> +		return -EIO;
> +	}
> +
> +	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
> +	if (ret)
> +		return ret;
> +	if (val) {
> +		dev_err(&maxim->client->dev, "Short to ground detected on:\n");
> +		for (i = 0; i < 4; i++) {
> +			if (val & 1 << i)
> +				dev_err(&maxim->client->dev, "string %d\n", i + 1);
> +		}
> +		return -EIO;
> +	}
> +
> +	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);

Shouldn't this be MAX25014_SHORT_LED?


> +	if (ret)
> +		return ret;
> +	if (val) {
> +		dev_err(&maxim->client->dev, "Shorted led detected on:\n");
> +		for (i = 0; i < 4; i++) {
> +			if (val & 1 << i)
> +				dev_err(&maxim->client->dev, "string %d\n", i + 1);
> +		}
> +		return -EIO;
> +	}
> +
> +	ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val);
> +	if (ret)
> +		return ret;
> +	/*
> +	 * The HW_RST bit always starts at 1 after power up.
> +	 * It is reset on first read, does not indicate an error.
> +	 */
> +	if (val && val != MAX25014_DIAG_HW_RST) {
> +		if (val & MAX25014_DIAG_OT)
> +			dev_err(&maxim->client->dev,
> +				"Overtemperature shutdown\n");
> +		if (val & MAX25014_DIAG_OTW)
> +			dev_err(&maxim->client->dev,
> +				 "Chip is getting too hot (>125C)\n");
> +		if (val & MAX25014_DIAG_BSTOV)
> +			dev_err(&maxim->client->dev,
> +				"Boost converter overvoltage\n");
> +		if (val & MAX25014_DIAG_BSTUV)
> +			dev_err(&maxim->client->dev,
> +				"Boost converter undervoltage\n");
> +		if (val & MAX25014_DIAG_IREFOOR)
> +			dev_err(&maxim->client->dev, "IREF out of range\n");
> +		return -EIO;
> +	}
> +	return 0;
> +}
> +
> +/*
> + * 1. disable unused strings
> + * 2. set dim mode
> + * 3. set setting register
> + * 4. enable the backlight
> + */
> +static int max25014_configure(struct max25014 *maxim, int initial_state)
> +{
> +	uint32_t val;
> +	int ret;
> +
> +	/*
> +	 * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
> +	 * it needs to be changed at all to prevent the backlight flashing when
> +	 * it is configured correctly by the bootloader
> +	 */

Attach the comment to the if statement rather than the read.


> +	ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
> +		if (initial_state == BACKLIGHT_POWER_ON) {
> +			ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
> +			if (ret)
> +				return ret;
> +		}
> +		ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(maxim->regmap, MAX25014_SETTING,
> +			   val & ~MAX25014_SETTING_FPWM);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(maxim->regmap, MAX25014_ISET,
> +			   maxim->iset | MAX25014_ISET_ENA |
> +			   MAX25014_ISET_PSEN);
> +	return ret;
> +}
> +
> +static int max25014_update_status(struct backlight_device *bl_dev)
> +{
> +	struct max25014 *maxim = bl_get_data(bl_dev);
> +	uint32_t reg;
> +	int ret;
> +
> +	if (backlight_is_blank(maxim->bl))
> +		bl_dev->props.brightness = 0;

This isn't right. Why would you change the backlight level just because
it is currently blanked (and sorry I missed this one last time).

> +
> +	reg  = TON_STEP * bl_dev->props.brightness;

The correct way to honour blanking is just go call
backlight_get_brightness() instead of reading the property directly.


> +
> +	/*
> +	 * 18 bit number lowest, 2 bits in first register,
> +	 * next lowest 8 in the L register, next 8 in the H register
> +	 * Seemingly setting the strength of only one string controls all of
> +	 * them, individual settings don't affect the outcome.
> +	 */
> +
> +	ret = regmap_write(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
> +	if (ret != 0)
> +		return ret;
> +	ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
> +	if (ret != 0)
> +		return ret;
> +	return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
> +}
> +
> +static const struct backlight_ops max25014_bl_ops = {
> +	.options = BL_CORE_SUSPENDRESUME,
> +	.update_status = max25014_update_status,
> +};
> +
> +static int max25014_parse_dt(struct max25014 *maxim,
> +			     uint32_t *initial_brightness)
> +{
> +	struct device *dev = &maxim->client->dev;
> +	struct device_node *node = dev->of_node;
> +	struct fwnode_handle *child;
> +	uint32_t strings[4];
> +	int res, i;
> +
> +	if (!node)
> +		return dev_err_probe(dev, -EINVAL, "no platform data\n");
> +
> +	child = device_get_next_child_node(dev, NULL);
> +	if (child) {
> +		res = fwnode_property_count_u32(child, "led-sources");
> +		if (res > 0) {
> +			fwnode_property_read_u32_array(child, "led-sources",
> +						       strings, res);
> +
> +			/* set all strings as disabled, then enable those in led-sources*/
> +			maxim->strings_mask = 0xf;
> +			for (i = 0; i < res; i++) {
> +				if (strings[i] <= 4)
> +					maxim->strings_mask &= ~BIT(strings[i]);
> +			}
> +		}
> +
> +		fwnode_property_read_u32(child, "default-brightness",
> +					 initial_brightness);
> +
> +		fwnode_handle_put(child);
> +	}
> +
> +	maxim->iset = MAX25014_ISET_DEFAULT_100;
> +	of_property_read_u32(node, "maxim,iset", &maxim->iset);
> +
> +	if (maxim->iset > 15)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Invalid iset, should be a value from 0-15, entered was %d\n",
> +				     maxim->iset);
> +
> +	if (*initial_brightness > 100)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Invalid initial brightness, should be a value from 0-100, entered was %d\n",
> +				     *initial_brightness);
> +
> +	return 0;
> +}
> +
> +static int max25014_probe(struct i2c_client *cl)
> +{
> +	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
> +	struct backlight_properties props;
> +	uint32_t initial_brightness = 50;
> +	struct backlight_device *bl;
> +	struct max25014 *maxim;
> +	int ret;
> +
> +	maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL);
> +	if (!maxim)
> +		return -ENOMEM;
> +
> +	maxim->client = cl;
> +
> +	ret = max25014_parse_dt(maxim, &initial_brightness);
> +	if (ret)
> +		return ret;
> +
> +	maxim->vin = devm_regulator_get(&maxim->client->dev, "power");
> +	if (IS_ERR(maxim->vin)) {
> +		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->vin),
> +				     "failed to get power-supply");
> +	}
> +
> +	ret = regulator_enable(maxim->vin);
> +	if (ret)
> +		return dev_err_probe(&maxim->client->dev, ret,
> +			"failed to enable power-supply\n");

Can this use devm_regulator_get_enable()?


> +
> +	maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
> +						GPIOD_OUT_HIGH);
> +	if (IS_ERR(maxim->enable)) {
> +		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
> +				    "failed to get enable gpio\n");
> +		goto disable_vin;
> +	}
> +
> +	/* Datasheet Electrical Characteristics tSTARTUP 2ms */
> +	fsleep(2000);
> +
> +	maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
> +	if (IS_ERR(maxim->regmap)) {
> +		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
> +			"failed to initialize the i2c regmap\n");
> +		goto disable_full;
> +	}
> +
> +	i2c_set_clientdata(cl, maxim);
> +
> +	ret = max25014_check_errors(maxim);
> +	if (ret) { /* error is already reported in the above function */
> +		goto disable_full;
> +	}
> +
> +	ret = max25014_initial_power_state(maxim);
> +	if (ret < 0) {
> +		dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n");
> +		goto disable_full;
> +	}
> +
> +	memset(&props, 0, sizeof(struct backlight_properties));
> +	props.type = BACKLIGHT_PLATFORM;
> +	props.max_brightness = MAX_BRIGHTNESS;
> +	props.brightness = initial_brightness;
> +	props.scale = BACKLIGHT_SCALE_LINEAR;
> +	props.power = ret;
> +
> +	ret = max25014_configure(maxim, ret);
> +	if (ret) {
> +		dev_err_probe(&maxim->client->dev, ret, "device config error");
> +		goto disable_full;
> +	}
> +
> +	bl = devm_backlight_device_register(&maxim->client->dev, id->name,
> +					    &maxim->client->dev, maxim,
> +					    &max25014_bl_ops, &props);
> +	if (IS_ERR(bl)) {
> +		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
> +				    "failed to register backlight\n");
> +		goto disable_full;
> +	}
> +
> +	maxim->bl = bl;
> +
> +	backlight_update_status(maxim->bl);
> +
> +	return 0;
> +
> +disable_full:
> +	gpiod_set_value_cansleep(maxim->enable, 0);

Why is this needed? It was only ever set by devm_gpiod_get_optional().

> +disable_vin:
> +	regulator_disable(maxim->vin);

This is also not needed if you use devm_regulator_get_enable().


> +	return ret;
> +}


Daniel.

Re: [PATCH v6 2/4] backlight: add max25014atg backlight

[Maud Spierings]

Thanks for the review.

On 12/4/25 17:17, Daniel Thompson wrote:
> On Mon, Dec 01, 2025 at 12:53:21PM +0100, Maud Spierings via B4 Relay wrote:
>> From: Maud Spierings <maudspierings@gocontroll.com>
>>
>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>> with integrated boost controller.
>>
>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> 
>> <snip>
> 
>> +static int max25014_check_errors(struct max25014 *maxim)
>> +{
>> +	uint32_t val;
>> +	uint8_t i;
>> +	int ret;
>> +
>> +	ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
>> +	if (ret)
>> +		return ret;
>> +	if (val) {
>> +		dev_err(&maxim->client->dev, "Open led strings detected on:\n");
>> +		for (i = 0; i < 4; i++) {
>> +			if (val & 1 << i)
>> +				dev_err(&maxim->client->dev, "string %d\n", i + 1);
>> +		}
>> +		return -EIO;
>> +	}
>> +
>> +	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
>> +	if (ret)
>> +		return ret;
>> +	if (val) {
>> +		dev_err(&maxim->client->dev, "Short to ground detected on:\n");
>> +		for (i = 0; i < 4; i++) {
>> +			if (val & 1 << i)
>> +				dev_err(&maxim->client->dev, "string %d\n", i + 1);
>> +		}
>> +		return -EIO;
>> +	}
>> +
>> +	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
> 
> Shouldn't this be MAX25014_SHORT_LED?

yep you are absolutely right

> 
>> +	if (ret)
>> +		return ret;
>> +	if (val) {
>> +		dev_err(&maxim->client->dev, "Shorted led detected on:\n");
>> +		for (i = 0; i < 4; i++) {
>> +			if (val & 1 << i)
>> +				dev_err(&maxim->client->dev, "string %d\n", i + 1);
>> +		}
>> +		return -EIO;
>> +	}
>> +
>> +	ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val);
>> +	if (ret)
>> +		return ret;
>> +	/*
>> +	 * The HW_RST bit always starts at 1 after power up.
>> +	 * It is reset on first read, does not indicate an error.
>> +	 */
>> +	if (val && val != MAX25014_DIAG_HW_RST) {
>> +		if (val & MAX25014_DIAG_OT)
>> +			dev_err(&maxim->client->dev,
>> +				"Overtemperature shutdown\n");
>> +		if (val & MAX25014_DIAG_OTW)
>> +			dev_err(&maxim->client->dev,
>> +				 "Chip is getting too hot (>125C)\n");
>> +		if (val & MAX25014_DIAG_BSTOV)
>> +			dev_err(&maxim->client->dev,
>> +				"Boost converter overvoltage\n");
>> +		if (val & MAX25014_DIAG_BSTUV)
>> +			dev_err(&maxim->client->dev,
>> +				"Boost converter undervoltage\n");
>> +		if (val & MAX25014_DIAG_IREFOOR)
>> +			dev_err(&maxim->client->dev, "IREF out of range\n");
>> +		return -EIO;
>> +	}
>> +	return 0;
>> +}
>> +
>> +/*
>> + * 1. disable unused strings
>> + * 2. set dim mode
>> + * 3. set setting register
>> + * 4. enable the backlight
>> + */
>> +static int max25014_configure(struct max25014 *maxim, int initial_state)
>> +{
>> +	uint32_t val;
>> +	int ret;
>> +
>> +	/*
>> +	 * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
>> +	 * it needs to be changed at all to prevent the backlight flashing when
>> +	 * it is configured correctly by the bootloader
>> +	 */
> 
> Attach the comment to the if statement rather than the read.

will do

> 
>> +	ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
>> +		if (initial_state == BACKLIGHT_POWER_ON) {
>> +			ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
>> +			if (ret)
>> +				return ret;
>> +		}
>> +		ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = regmap_write(maxim->regmap, MAX25014_SETTING,
>> +			   val & ~MAX25014_SETTING_FPWM);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = regmap_write(maxim->regmap, MAX25014_ISET,
>> +			   maxim->iset | MAX25014_ISET_ENA |
>> +			   MAX25014_ISET_PSEN);
>> +	return ret;
>> +}
>> +
>> +static int max25014_update_status(struct backlight_device *bl_dev)
>> +{
>> +	struct max25014 *maxim = bl_get_data(bl_dev);
>> +	uint32_t reg;
>> +	int ret;
>> +
>> +	if (backlight_is_blank(maxim->bl))
>> +		bl_dev->props.brightness = 0;
> 
> This isn't right. Why would you change the backlight level just because
> it is currently blanked (and sorry I missed this one last time).

so just remove this bit then jeah?

>> +
>> +	reg  = TON_STEP * bl_dev->props.brightness;
> 
> The correct way to honour blanking is just go call
> backlight_get_brightness() instead of reading the property directly.

will do.

> 
>> +
>> +	/*
>> +	 * 18 bit number lowest, 2 bits in first register,
>> +	 * next lowest 8 in the L register, next 8 in the H register
>> +	 * Seemingly setting the strength of only one string controls all of
>> +	 * them, individual settings don't affect the outcome.
>> +	 */
>> +
>> +	ret = regmap_write(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
>> +	if (ret != 0)
>> +		return ret;
>> +	ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
>> +	if (ret != 0)
>> +		return ret;
>> +	return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
>> +}
>> +
>> +static const struct backlight_ops max25014_bl_ops = {
>> +	.options = BL_CORE_SUSPENDRESUME,
>> +	.update_status = max25014_update_status,
>> +};
>> +
>> +static int max25014_parse_dt(struct max25014 *maxim,
>> +			     uint32_t *initial_brightness)
>> +{
>> +	struct device *dev = &maxim->client->dev;
>> +	struct device_node *node = dev->of_node;
>> +	struct fwnode_handle *child;
>> +	uint32_t strings[4];
>> +	int res, i;
>> +
>> +	if (!node)
>> +		return dev_err_probe(dev, -EINVAL, "no platform data\n");
>> +
>> +	child = device_get_next_child_node(dev, NULL);
>> +	if (child) {
>> +		res = fwnode_property_count_u32(child, "led-sources");
>> +		if (res > 0) {
>> +			fwnode_property_read_u32_array(child, "led-sources",
>> +						       strings, res);
>> +
>> +			/* set all strings as disabled, then enable those in led-sources*/
>> +			maxim->strings_mask = 0xf;
>> +			for (i = 0; i < res; i++) {
>> +				if (strings[i] <= 4)
>> +					maxim->strings_mask &= ~BIT(strings[i]);
>> +			}
>> +		}
>> +
>> +		fwnode_property_read_u32(child, "default-brightness",
>> +					 initial_brightness);
>> +
>> +		fwnode_handle_put(child);
>> +	}
>> +
>> +	maxim->iset = MAX25014_ISET_DEFAULT_100;
>> +	of_property_read_u32(node, "maxim,iset", &maxim->iset);
>> +
>> +	if (maxim->iset > 15)
>> +		return dev_err_probe(dev, -EINVAL,
>> +				     "Invalid iset, should be a value from 0-15, entered was %d\n",
>> +				     maxim->iset);
>> +
>> +	if (*initial_brightness > 100)
>> +		return dev_err_probe(dev, -EINVAL,
>> +				     "Invalid initial brightness, should be a value from 0-100, entered was %d\n",
>> +				     *initial_brightness);
>> +
>> +	return 0;
>> +}
>> +
>> +static int max25014_probe(struct i2c_client *cl)
>> +{
>> +	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
>> +	struct backlight_properties props;
>> +	uint32_t initial_brightness = 50;
>> +	struct backlight_device *bl;
>> +	struct max25014 *maxim;
>> +	int ret;
>> +
>> +	maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL);
>> +	if (!maxim)
>> +		return -ENOMEM;
>> +
>> +	maxim->client = cl;
>> +
>> +	ret = max25014_parse_dt(maxim, &initial_brightness);
>> +	if (ret)
>> +		return ret;
>> +
>> +	maxim->vin = devm_regulator_get(&maxim->client->dev, "power");
>> +	if (IS_ERR(maxim->vin)) {
>> +		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->vin),
>> +				     "failed to get power-supply");
>> +	}
>> +
>> +	ret = regulator_enable(maxim->vin);
>> +	if (ret)
>> +		return dev_err_probe(&maxim->client->dev, ret,
>> +			"failed to enable power-supply\n");
> 
> Can this use devm_regulator_get_enable()?

Yeah guess I'll just switch to that for now, if ever power management 
gets implemented it can be figured out if regulator control is desired.

> 
>> +
>> +	maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
>> +						GPIOD_OUT_HIGH);
>> +	if (IS_ERR(maxim->enable)) {
>> +		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
>> +				    "failed to get enable gpio\n");
>> +		goto disable_vin;
>> +	}
>> +
>> +	/* Datasheet Electrical Characteristics tSTARTUP 2ms */
>> +	fsleep(2000);
>> +
>> +	maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
>> +	if (IS_ERR(maxim->regmap)) {
>> +		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
>> +			"failed to initialize the i2c regmap\n");
>> +		goto disable_full;
>> +	}
>> +
>> +	i2c_set_clientdata(cl, maxim);
>> +
>> +	ret = max25014_check_errors(maxim);
>> +	if (ret) { /* error is already reported in the above function */
>> +		goto disable_full;
>> +	}
>> +
>> +	ret = max25014_initial_power_state(maxim);
>> +	if (ret < 0) {
>> +		dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n");
>> +		goto disable_full;
>> +	}
>> +
>> +	memset(&props, 0, sizeof(struct backlight_properties));
>> +	props.type = BACKLIGHT_PLATFORM;
>> +	props.max_brightness = MAX_BRIGHTNESS;
>> +	props.brightness = initial_brightness;
>> +	props.scale = BACKLIGHT_SCALE_LINEAR;
>> +	props.power = ret;
>> +
>> +	ret = max25014_configure(maxim, ret);
>> +	if (ret) {
>> +		dev_err_probe(&maxim->client->dev, ret, "device config error");
>> +		goto disable_full;
>> +	}
>> +
>> +	bl = devm_backlight_device_register(&maxim->client->dev, id->name,
>> +					    &maxim->client->dev, maxim,
>> +					    &max25014_bl_ops, &props);
>> +	if (IS_ERR(bl)) {
>> +		ret = dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
>> +				    "failed to register backlight\n");
>> +		goto disable_full;
>> +	}
>> +
>> +	maxim->bl = bl;
>> +
>> +	backlight_update_status(maxim->bl);
>> +
>> +	return 0;
>> +
>> +disable_full:
>> +	gpiod_set_value_cansleep(maxim->enable, 0);
> 
> Why is this needed? It was only ever set by devm_gpiod_get_optional().

oops thats a leftover from before that change, good spot.

>> +disable_vin:
>> +	regulator_disable(maxim->vin);
> 
> This is also not needed if you use devm_regulator_get_enable().

jeah I'll drop this then too

kind regards,
Maud

Re: [PATCH v6 2/4] backlight: add max25014atg backlight

[Daniel Thompson]

On Fri, Dec 05, 2025 at 04:20:55PM +0100, Maud Spierings wrote:
> Thanks for the review.
>
> On 12/4/25 17:17, Daniel Thompson wrote:
> > On Mon, Dec 01, 2025 at 12:53:21PM +0100, Maud Spierings via B4 Relay wrote:
> > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> > > with integrated boost controller.
> > >
> > > Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>
> <snip>
>
> > > +static int max25014_update_status(struct backlight_device *bl_dev)
> > > +{
> > > +	struct max25014 *maxim = bl_get_data(bl_dev);
> > > +	uint32_t reg;
> > > +	int ret;
> > > +
> > > +	if (backlight_is_blank(maxim->bl))
> > > +		bl_dev->props.brightness = 0;
> >
> > This isn't right. Why would you change the backlight level just because
> > it is currently blanked (and sorry I missed this one last time).
>
> so just remove this bit then jeah?

Yes. backlight_get_brightness() is all you should need.


> > > +
> > > +	reg  = TON_STEP * bl_dev->props.brightness;
> >
> > The correct way to honour blanking is just go call
> > backlight_get_brightness() instead of reading the property directly.
>
> will do.

Thanks.


Daniel.

[PATCH v6 3/4] arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

Add the missing backlight driver.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
index e3965caca6be..0e2914861154 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
+++ b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
@@ -17,6 +17,7 @@
 
 	panel {
 		compatible = "boe,av101hdt-a10";
+		backlight = <&backlight>;
 		enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
 		pinctrl-0 = <&pinctrl_panel>;
 		pinctrl-names = "default";
@@ -40,7 +41,36 @@ reg_vbus: regulator-vbus {
 	};
 };
 
+&i2c4 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+
+		led@0 {
+			reg = <0>;
+			led-sources = <0 1 2>;
+			default-brightness = <50>;
+		};
+	};
+};
+
 &iomuxc {
+	pinctrl_backlight: backlightgrp {
+		fsl,pins = <
+			MX8MP_IOMUXC_GPIO1_IO04__GPIO1_IO04
+				(MX8MP_PULL_UP | MX8MP_PULL_ENABLE)
+		>;
+	};
+
 	pinctrl_panel: panelgrp {
 		fsl,pins = <
 			MX8MP_IOMUXC_GPIO1_IO07__GPIO1_IO07

-- 
2.52.0

[PATCH v6 4/4] arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

Add the missing backlight.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 ...x8p-ml81-moduline-display-106-av123z7m-n17.dtso | 25 +++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
index 3eb665ce9d5d..786a04ef40c8 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
+++ b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
@@ -16,6 +16,7 @@
 
 	panel {
 		compatible = "boe,av123z7m-n17";
+		backlight = <&backlight>;
 		enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
 		pinctrl-0 = <&pinctrl_panel>;
 		pinctrl-names = "default";
@@ -91,10 +92,32 @@ lvds1_out: endpoint {
 		};
 	};
 
-	/* max25014 @ 0x6f */
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+
+		led@0 {
+			reg = <0>;
+			led-sources = <0 1 2 3>;
+			default-brightness = <50>;
+		};
+	};
 };
 
 &iomuxc {
+	pinctrl_backlight: backlightgrp {
+		fsl,pins = <
+			MX8MP_IOMUXC_GPIO1_IO04__GPIO1_IO04
+				(MX8MP_PULL_UP | MX8MP_PULL_ENABLE)
+		>;
+	};
+
 	pinctrl_lvds_bridge: lvdsbridgegrp {
 		fsl,pins = <
 			MX8MP_IOMUXC_SAI1_TXD2__GPIO4_IO14

-- 
2.52.0