[PATCH v3 0/3] Add support for is31fl3236a LED controller

[PATCH v3 0/3] Add support for is31fl3236a LED controller

[Pawel Zalewski]

This series of patches adds support for the is31fl3236a led
controller. The main difference between this IC and the
is31fl3236 is that there is a new parameter/register that
moves the operating frequency of the PWM outputs out of 
the audible range.

To support the new register a property was added in the dt-bindings,
as this property is at the board layout level ie. not all
boards will have analog audio and have to worry about it.

To add the new property the old .txt binding documentation was
ported to .yaml format. There was a previous attempt to do this
in 2024 but the original author has never acted on the feedback
given [1]. So I have implemented changes requested in that 
review and added his Signed-off-by.

The new functionality was tested by scoping the PWM signal. Out of
reset the IC is in 3kHz mode, thus action is taken only if the new
boolean value is set to true in the device tree.

[1] https://lore.kernel.org/linux-leds/20240701-overview-video-34f025ede104@spud/

Changes in v2:
- Added cover letter
- Ported dt-binding to yaml
- Refactored driver module
- Link to v1: https://lore.kernel.org/linux-leds/CAA6zWZ+TbcHrZaZ0ottm0s1mhCLa8TXASii47WKSLn2_zV95bw@mail.gmail.com/T/#t

Changes in v3:
- Aligned/refactored code properly in C module
- Refactored dt-bindings yml file
- Link to v2: https://lore.kernel.org/r/20250627-leds-is31fl3236a-v2-0-f6ef7495ce65@thegoodpenguin.co.uk

Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
---
Lucca Fachinetti (1):
      dt-bindings: leds: is31fl32xx: convert the binding to yaml

Pawel Zalewski (2):
      leds/leds-is31fl32xx: add support for is31fl3236a
      dt-bindings: leds: issi,is31fl3236: add issi,22kHz-pwm property

 .../devicetree/bindings/leds/issi,is31fl3236.yaml  | 104 +++++++++++++++++++++
 .../devicetree/bindings/leds/leds-is31fl32xx.txt   |  52 -----------
 drivers/leds/leds-is31fl32xx.c                     |  35 +++++++
 3 files changed, 139 insertions(+), 52 deletions(-)
---
base-commit: 52da431bf03b5506203bca27fe14a97895c80faf
change-id: 20250625-leds-is31fl3236a-39cf52f969c7

Best regards,
-- 
Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>

[PATCH v3 1/3] leds/leds-is31fl32xx: add support for is31fl3236a

[Pawel Zalewski]

Add an additional and optional control register for setting
the output PWM frequency to 22kHz. The default is 3kHz and
this option puts the operational frequency outside of the
audible range.

Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
---
 drivers/leds/leds-is31fl32xx.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/leds/leds-is31fl32xx.c b/drivers/leds/leds-is31fl32xx.c
index 8793330dd4142f49f15d6ee9d87468c08509859f..c8e27c219177e8e7a17738fbd3bba84340d9776f 100644
--- a/drivers/leds/leds-is31fl32xx.c
+++ b/drivers/leds/leds-is31fl32xx.c
@@ -32,6 +32,8 @@
 #define IS31FL3216_CONFIG_SSD_ENABLE  BIT(7)
 #define IS31FL3216_CONFIG_SSD_DISABLE 0
 
+#define IS31FL32XX_PWM_FREQUENCY_22kHz  0x01
+
 struct is31fl32xx_priv;
 struct is31fl32xx_led_data {
 	struct led_classdev cdev;
@@ -53,6 +55,7 @@ struct is31fl32xx_priv {
  * @pwm_update_reg      : address of PWM Update register
  * @global_control_reg  : address of Global Control register (optional)
  * @reset_reg           : address of Reset register (optional)
+ * @output_frequency_setting_reg: address of output frequency register (optional)
  * @pwm_register_base   : address of first PWM register
  * @pwm_registers_reversed: : true if PWM registers count down instead of up
  * @led_control_register_base : address of first LED control register (optional)
@@ -76,6 +79,7 @@ struct is31fl32xx_chipdef {
 	u8	pwm_update_reg;
 	u8	global_control_reg;
 	u8	reset_reg;
+	u8	output_frequency_setting_reg;
 	u8	pwm_register_base;
 	bool	pwm_registers_reversed;
 	u8	led_control_register_base;
@@ -90,6 +94,19 @@ static const struct is31fl32xx_chipdef is31fl3236_cdef = {
 	.pwm_update_reg				= 0x25,
 	.global_control_reg			= 0x4a,
 	.reset_reg				= 0x4f,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
+	.pwm_register_base			= 0x01,
+	.led_control_register_base		= 0x26,
+	.enable_bits_per_led_control_register	= 1,
+};
+
+static const struct is31fl32xx_chipdef is31fl3236a_cdef = {
+	.channels				= 36,
+	.shutdown_reg				= 0x00,
+	.pwm_update_reg				= 0x25,
+	.global_control_reg			= 0x4a,
+	.reset_reg				= 0x4f,
+	.output_frequency_setting_reg		= 0x4b,
 	.pwm_register_base			= 0x01,
 	.led_control_register_base		= 0x26,
 	.enable_bits_per_led_control_register	= 1,
@@ -101,6 +118,7 @@ static const struct is31fl32xx_chipdef is31fl3235_cdef = {
 	.pwm_update_reg				= 0x25,
 	.global_control_reg			= 0x4a,
 	.reset_reg				= 0x4f,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
 	.pwm_register_base			= 0x05,
 	.led_control_register_base		= 0x2a,
 	.enable_bits_per_led_control_register	= 1,
@@ -112,6 +130,7 @@ static const struct is31fl32xx_chipdef is31fl3218_cdef = {
 	.pwm_update_reg				= 0x16,
 	.global_control_reg			= IS31FL32XX_REG_NONE,
 	.reset_reg				= 0x17,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
 	.pwm_register_base			= 0x01,
 	.led_control_register_base		= 0x13,
 	.enable_bits_per_led_control_register	= 6,
@@ -126,6 +145,7 @@ static const struct is31fl32xx_chipdef is31fl3216_cdef = {
 	.pwm_update_reg				= 0xB0,
 	.global_control_reg			= IS31FL32XX_REG_NONE,
 	.reset_reg				= IS31FL32XX_REG_NONE,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
 	.pwm_register_base			= 0x10,
 	.pwm_registers_reversed			= true,
 	.led_control_register_base		= 0x01,
@@ -363,8 +383,21 @@ static struct is31fl32xx_led_data *is31fl32xx_find_led_data(
 static int is31fl32xx_parse_dt(struct device *dev,
 			       struct is31fl32xx_priv *priv)
 {
+	const struct is31fl32xx_chipdef *cdef = priv->cdef;
 	int ret = 0;
 
+	if ((cdef->output_frequency_setting_reg != IS31FL32XX_REG_NONE) &&
+	    of_property_read_bool(dev_of_node(dev), "issi,22kHz-pwm")) {
+
+		ret = is31fl32xx_write(priv, cdef->output_frequency_setting_reg,
+				       IS31FL32XX_PWM_FREQUENCY_22kHz);
+
+		if (ret) {
+			dev_err(dev, "Failed to write output PWM frequency register\n");
+			return ret;
+		}
+	}
+
 	for_each_available_child_of_node_scoped(dev_of_node(dev), child) {
 		struct led_init_data init_data = {};
 		struct is31fl32xx_led_data *led_data =
@@ -405,6 +438,7 @@ static int is31fl32xx_parse_dt(struct device *dev,
 
 static const struct of_device_id of_is31fl32xx_match[] = {
 	{ .compatible = "issi,is31fl3236", .data = &is31fl3236_cdef, },
+	{ .compatible = "issi,is31fl3236a", .data = &is31fl3236a_cdef, },
 	{ .compatible = "issi,is31fl3235", .data = &is31fl3235_cdef, },
 	{ .compatible = "issi,is31fl3218", .data = &is31fl3218_cdef, },
 	{ .compatible = "si-en,sn3218",    .data = &is31fl3218_cdef, },
@@ -466,6 +500,7 @@ static void is31fl32xx_remove(struct i2c_client *client)
  */
 static const struct i2c_device_id is31fl32xx_id[] = {
 	{ "is31fl3236" },
+	{ "is31fl3236a" },
 	{ "is31fl3235" },
 	{ "is31fl3218" },
 	{ "sn3218" },

-- 
2.48.1

Re: [PATCH v3 1/3] leds/leds-is31fl32xx: add support for is31fl3236a

[Krzysztof Kozlowski]

On Tue, Jul 08, 2025 at 03:59:45PM +0100, Pawel Zalewski wrote:
> +
>  	for_each_available_child_of_node_scoped(dev_of_node(dev), child) {
>  		struct led_init_data init_data = {};
>  		struct is31fl32xx_led_data *led_data =
> @@ -405,6 +438,7 @@ static int is31fl32xx_parse_dt(struct device *dev,
>  
>  static const struct of_device_id of_is31fl32xx_match[] = {
>  	{ .compatible = "issi,is31fl3236", .data = &is31fl3236_cdef, },
> +	{ .compatible = "issi,is31fl3236a", .data = &is31fl3236a_cdef, },

Bindings go before the users (see submitting patches in DT).

Best regards,
Krzysztof

Re: [PATCH v3 1/3] leds/leds-is31fl32xx: add support for is31fl3236a

[Pawel Zalewski]

> Bindings go before the users (see submitting patches in DT).

I think I was confused with point 7 stating that dt-binding should come
last within a series and point 6 stating it is only regarding DTS files,
missed point 5 altogether... Thanks !

Re: [PATCH v3 1/3] leds/leds-is31fl32xx: add support for is31fl3236a

[Krzysztof Kozlowski]

On 14/07/2025 11:09, Pawel Zalewski wrote:
>> Bindings go before the users (see submitting patches in DT).
> 
> I think I was confused with point 7 stating that dt-binding should come

Point 7 speaks nothing about DT Bindings.

> last within a series and point 6 stating it is only regarding DTS files,

Neither point 6 says that it regards only DTS files.

> missed point 5 altogether... Thanks !

Are you sure you read correct and latest file?


Best regards,
Krzysztof

[PATCH v3 2/3] dt-bindings: leds: is31fl32xx: convert the binding to yaml

[Pawel Zalewski]

From: Lucca Fachinetti <luccafachinetti@gmail.com>

Keep the old maintainers field as is.
Add datasheets for reference, NB that I was not able to find an
up-to-date, funtional direct URL for si-en products datasheet
so they were skipped.

Signed-off-by: Lucca Fachinetti <luccafachinetti@gmail.com>
Co-developed-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
---
 .../devicetree/bindings/leds/issi,is31fl3236.yaml  | 98 ++++++++++++++++++++++
 .../devicetree/bindings/leds/leds-is31fl32xx.txt   | 52 ------------
 2 files changed, 98 insertions(+), 52 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..d0f9add5af01ac06c4bb87b0cd0faec71d0ef37c
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
@@ -0,0 +1,98 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/issi,is31fl3236.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: is31fl32xx and Si-En SN32xx IC LED driver
+
+maintainers:
+  - Pavel Machek <pavel@ucw.cz>
+  - Lee Jones <lee@kernel.org>
+
+description: |
+  The is31fl32xx/SN32xx family of LED drivers are I2C devices with multiple
+  constant-current channels, each with independent 256-level PWM control.
+  Each LED is represented as a sub-node of the device.
+
+  For more product information please see the links below:
+    https://www.lumissil.com/assets/pdf/core/IS31FL3236_DS.pdf
+    https://www.lumissil.com/assets/pdf/core/IS31FL3236A_DS.pdf
+    https://www.lumissil.com/assets/pdf/core/IS31FL3235_DS.pdf
+    https://www.lumissil.com/assets/pdf/core/IS31FL3218_DS.pdf
+    https://www.lumissil.com/assets/pdf/core/IS31FL3216_DS.pdf
+
+properties:
+  compatible:
+    enum:
+      - issi,is31fl3236
+      - issi,is31fl3236a
+      - issi,is31fl3235
+      - issi,is31fl3218
+      - issi,is31fl3216
+      - si-en,sn3218
+      - si-en,sn3216
+
+  reg:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^led@[1-9a-f]+$":
+    type: object
+    $ref: common.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        description:
+          LED channel number (1..N)
+        minimum: 1
+        maximum: 36
+
+    required:
+      - reg
+
+required:
+  - compatible
+  - reg
+  - "#size-cells"
+  - "#address-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/leds/common.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        led-controller@3c {
+            compatible = "issi,is31fl3236";
+            reg = <0x3c>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            led@1 {
+                reg = <0x1>;
+                label = "led1:red";
+            };
+            led@2 {
+                reg = <0x2>;
+                label = "led1:green";
+            };
+            led@3 {
+                reg = <0x3>;
+                label = "led1:blue";
+            };
+        };
+    };
+...
+
diff --git a/Documentation/devicetree/bindings/leds/leds-is31fl32xx.txt b/Documentation/devicetree/bindings/leds/leds-is31fl32xx.txt
deleted file mode 100644
index 926c2117942c4dc200fcd68156864f544b11a326..0000000000000000000000000000000000000000
--- a/Documentation/devicetree/bindings/leds/leds-is31fl32xx.txt
+++ /dev/null
@@ -1,52 +0,0 @@
-Binding for ISSI IS31FL32xx and Si-En SN32xx LED Drivers
-
-The IS31FL32xx/SN32xx family of LED drivers are I2C devices with multiple
-constant-current channels, each with independent 256-level PWM control.
-Each LED is represented as a sub-node of the device.
-
-Required properties:
-- compatible: one of
-	issi,is31fl3236
-	issi,is31fl3235
-	issi,is31fl3218
-	issi,is31fl3216
-	si-en,sn3218
-	si-en,sn3216
-- reg: I2C slave address
-- address-cells : must be 1
-- size-cells : must be 0
-
-LED sub-node properties:
-- reg : LED channel number (1..N)
-- label :  (optional)
-  see Documentation/devicetree/bindings/leds/common.txt
-- linux,default-trigger :  (optional)
-  see Documentation/devicetree/bindings/leds/common.txt
-
-
-Example:
-
-is31fl3236: led-controller@3c {
-	compatible = "issi,is31fl3236";
-	reg = <0x3c>;
-	#address-cells = <1>;
-	#size-cells = <0>;
-
-	led@1 {
-		reg = <1>;
-		label = "EB:blue:usr0";
-	};
-	led@2 {
-		reg = <2>;
-		label = "EB:blue:usr1";
-	};
-	...
-	led@36 {
-		reg = <36>;
-		label = "EB:blue:usr35";
-	};
-};
-
-For more product information please see the links below:
-http://www.issi.com/US/product-analog-fxled-driver.shtml
-http://www.si-en.com/product.asp?parentid=890

-- 
2.48.1

Re: [PATCH v3 2/3] dt-bindings: leds: is31fl32xx: convert the binding to yaml

[Krzysztof Kozlowski]

On Tue, Jul 08, 2025 at 03:59:46PM +0100, Pawel Zalewski wrote:
> From: Lucca Fachinetti <luccafachinetti@gmail.com>
> 
> Keep the old maintainers field as is.
> Add datasheets for reference, NB that I was not able to find an
> up-to-date, funtional direct URL for si-en products datasheet
> so they were skipped.
> 
> Signed-off-by: Lucca Fachinetti <luccafachinetti@gmail.com>
> Co-developed-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
> Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
> ---
>  .../devicetree/bindings/leds/issi,is31fl3236.yaml  | 98 ++++++++++++++++++++++
>  .../devicetree/bindings/leds/leds-is31fl32xx.txt   | 52 ------------
>  2 files changed, 98 insertions(+), 52 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..d0f9add5af01ac06c4bb87b0cd0faec71d0ef37c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
> @@ -0,0 +1,98 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/issi,is31fl3236.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: is31fl32xx and Si-En SN32xx IC LED driver

Driver as Linux driver or LED driver? If the first, then drop.

> +
> +maintainers:
> +  - Pavel Machek <pavel@ucw.cz>
> +  - Lee Jones <lee@kernel.org>

These should be people interested in this hardware, not subsystem
maintainers.

> +
> +description: |
> +  The is31fl32xx/SN32xx family of LED drivers are I2C devices with multiple
> +  constant-current channels, each with independent 256-level PWM control.
> +  Each LED is represented as a sub-node of the device.
> +
> +  For more product information please see the links below:
> +    https://www.lumissil.com/assets/pdf/core/IS31FL3236_DS.pdf
> +    https://www.lumissil.com/assets/pdf/core/IS31FL3236A_DS.pdf
> +    https://www.lumissil.com/assets/pdf/core/IS31FL3235_DS.pdf
> +    https://www.lumissil.com/assets/pdf/core/IS31FL3218_DS.pdf
> +    https://www.lumissil.com/assets/pdf/core/IS31FL3216_DS.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - issi,is31fl3236
> +      - issi,is31fl3236a
> +      - issi,is31fl3235
> +      - issi,is31fl3218
> +      - issi,is31fl3216
> +      - si-en,sn3218
> +      - si-en,sn3216
> +
> +  reg:
> +    maxItems: 1
> +
> +  '#address-cells':
> +    const: 1
> +
> +  "#size-cells":

Keep consistent quotes, either " or '. You made different choice for the
same properties even...

> +    const: 0
> +
> +patternProperties:
> +  "^led@[1-9a-f]+$":

Pattern does not match entirely the reg constraints. 36 is 0x24.


Best regards,
Krzysztof

Re: [PATCH v3 2/3] dt-bindings: leds: is31fl32xx: convert the binding to yaml

[Pawel Zalewski]

> Driver as Linux driver or LED driver? If the first, then drop.
LED driver, might not be obvious, could change to controller,
however the datasheet refers to the device "LED driver".

> These should be people interested in this hardware, not subsystem
> maintainers.

I will let maintainers decide who should be included here perhaps ?

> Keep consistent quotes, either " or '. You made different choice for the
> same properties even...

Copied over from original poster, have not spotted that before, thanks.

> Pattern does not match entirely the reg constraints. 36 is 0x24.

Pattern allows for one or more hexadecimal values starting from 1,
so the second number should start from zero is the second error here.

Thanks !

Re: [PATCH v3 2/3] dt-bindings: leds: is31fl32xx: convert the binding to yaml

[Krzysztof Kozlowski]

On 14/07/2025 11:16, Pawel Zalewski wrote:
> 
>> Pattern does not match entirely the reg constraints. 36 is 0x24.
> 
> Pattern allows for one or more hexadecimal values starting from 1,
> so the second number should start from zero is the second error here.

You cut entire context so I really do not know how the code looks like.
Anyway, they do not match and this needs to be fixed.

Best regards,
Krzysztof

Re: [PATCH v3 2/3] dt-bindings: leds: is31fl32xx: convert the binding to yaml

[Krzysztof Kozlowski]

On Tue, Jul 08, 2025 at 03:59:46PM +0100, Pawel Zalewski wrote:
> From: Lucca Fachinetti <luccafachinetti@gmail.com>
> 
> Keep the old maintainers field as is.

I don't understand this. There were no old maintainers of this binding
and driver.

Best regards,
Krzysztof

[PATCH v3 3/3] dt-bindings: leds: issi,is31fl3236: add issi,22kHz-pwm property

[Pawel Zalewski]

Add an additional and optional control property for setting
the output PWM frequency to 22kHz. The default is 3kHz and
this option puts the operational frequency outside of the
audible range.

Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
---
 Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
index d0f9add5af01ac06c4bb87b0cd0faec71d0ef37c..5bce0fc48f84c7ae804e6522e312c51ed2d77bc5 100644
--- a/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
+++ b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
@@ -42,6 +42,12 @@ properties:
   "#size-cells":
     const: 0
 
+  issi,22kHz-pwm:
+    type: boolean
+    description:
+      When present, the chip's PWM will operate at ~22kHz as opposed
+      to ~3kHz to move the operating frequency out of the audible range.
+
 patternProperties:
   "^led@[1-9a-f]+$":
     type: object

-- 
2.48.1

Re: [PATCH v3 3/3] dt-bindings: leds: issi,is31fl3236: add issi,22kHz-pwm property

[Krzysztof Kozlowski]

On Tue, Jul 08, 2025 at 03:59:47PM +0100, Pawel Zalewski wrote:
> Add an additional and optional control property for setting
> the output PWM frequency to 22kHz. The default is 3kHz and
> this option puts the operational frequency outside of the
> audible range.
> 
> Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
> ---
>  Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
> index d0f9add5af01ac06c4bb87b0cd0faec71d0ef37c..5bce0fc48f84c7ae804e6522e312c51ed2d77bc5 100644
> --- a/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
> +++ b/Documentation/devicetree/bindings/leds/issi,is31fl3236.yaml
> @@ -42,6 +42,12 @@ properties:
>    "#size-cells":
>      const: 0
>  
> +  issi,22kHz-pwm:
> +    type: boolean
> +    description:
> +      When present, the chip's PWM will operate at ~22kHz as opposed
> +      to ~3kHz to move the operating frequency out of the audible range.
> +

According to your driver this is not applicable to every device, so you
need allOf:if:then: block at the end, before additionalProperties,
restricting it per variant:

.....
  then:
    properties:
      issi,22kHz-pwm: false

If that's not true, then commit msg should explain that - from the
hardware perspective.

Best regards,
Krzysztof