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SubjectRe: [PATCH] WIP: dt-bindings: arm: hwmon: gpio-fan: Convert txt bindings to yaml



On Tue, Oct 19 2021 at 16:35:17 -0500, Rob Herring <robh@kernel.org>
wrote:
> On Sat, Oct 09, 2021 at 12:43:09PM +0200, David Heidelberg wrote:
>> Convert fan devices connected to GPIOs to the YAML syntax.
>>
>> Signed-off-by: David Heidelberg <david@ixit.cz>
>> ---
>> .../devicetree/bindings/hwmon/gpio-fan.txt | 41 -----------
>> .../devicetree/bindings/hwmon/gpio-fan.yaml | 69
>> +++++++++++++++++++
>> 2 files changed, 69 insertions(+), 41 deletions(-)
>> delete mode 100644
>> Documentation/devicetree/bindings/hwmon/gpio-fan.txt
>> create mode 100644
>> Documentation/devicetree/bindings/hwmon/gpio-fan.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/hwmon/gpio-fan.txt
>> b/Documentation/devicetree/bindings/hwmon/gpio-fan.txt
>> deleted file mode 100644
>> index f4cfa350f6a1..000000000000
>> --- a/Documentation/devicetree/bindings/hwmon/gpio-fan.txt
>> +++ /dev/null
>> @@ -1,41 +0,0 @@
>> -Bindings for fan connected to GPIO lines
>> -
>> -Required properties:
>> -- compatible : "gpio-fan"
>> -
>> -Optional properties:
>> -- gpios: Specifies the pins that map to bits in the control value,
>> - ordered MSB-->LSB.
>> -- gpio-fan,speed-map: A mapping of possible fan RPM speeds and the
>> - control value that should be set to achieve them. This array
>> - must have the RPM values in ascending order.
>> -- alarm-gpios: This pin going active indicates something is wrong
>> with
>> - the fan, and a udev event will be fired.
>> -- #cooling-cells: If used as a cooling device, must be <2>
>> - Also see:
>> -
>> Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml
>> - min and max states are derived from the speed-map of the fan.
>> -
>> -Note: At least one the "gpios" or "alarm-gpios" properties must be
>> set.
>> -
>> -Examples:
>> -
>> - gpio_fan {
>> - compatible = "gpio-fan";
>> - gpios = <&gpio1 14 1
>> - &gpio1 13 1>;
>> - gpio-fan,speed-map = <0 0
>> - 3000 1
>> - 6000 2>;
>> - alarm-gpios = <&gpio1 15 1>;
>> - };
>> - gpio_fan_cool: gpio_fan {
>> - compatible = "gpio-fan";
>> - gpios = <&gpio2 14 1
>> - &gpio2 13 1>;
>> - gpio-fan,speed-map = <0 0>,
>> - <3000 1>,
>> - <6000 2>;
>> - alarm-gpios = <&gpio2 15 1>;
>> - #cooling-cells = <2>; /* min followed by max */
>> - };
>> diff --git a/Documentation/devicetree/bindings/hwmon/gpio-fan.yaml
>> b/Documentation/devicetree/bindings/hwmon/gpio-fan.yaml
>> new file mode 100644
>> index 000000000000..e2db65d58a92
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/hwmon/gpio-fan.yaml
>> @@ -0,0 +1,69 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: "http://devicetree.org/schemas/hwmon/gpio-fan.yaml#"
>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>> +
>> +title: Bindings for fan connected to GPIO lines
>> +
>> +maintainers:
>> + - Rob Herring <robh+dt@kernel.org>
> Just robh@kernel.org
>
>> +
>> +properties:
>> + compatible:
>> + const: gpio-fan
>> +
>> + gpios:
>> + description: |
>> + Specifies the pins that map to bits in the control value,
>> + ordered MSB-->LSB.
>
> minItems: 1
> maxItems: 7 ?
>
>> +
>> + gpio-fan,speed-map:
>> + $ref: /schemas/types.yaml#/definitions/uint32-array
>> + minItems: 4
>> + maxItems: 254
>> + description: |
>> + A mapping of possible fan RPM speeds and the
>> + control value that should be set to achieve them. This array
>> + must have the RPM values in ascending order.
>
> Really this should be a uint32-matrix with this schema:
>
> items:
> minItems: 2
> maxItems: 127
> items:
> - description: fan speed in RPMs
> - description: control value
>
>> +
>> + alarm-gpios:
>> + description: |
>> + This pin going active indicates something is wrong with
>> + the fan, and a udev event will be fired.
>
> maxItems: 1
>
> udev is a linuxism and shouldn't be in the binding.
>
>> +
>> + '#cooling-cells':
>> + const: 2
>> +
>> +required:
>> + - compatible
>> + - gpio-fan,speed-map
>> +
>> +anyOf:
>> + - required: [gpios]
>
> How is 'gpios' not always required?
>
>> + - required: [alarm-gpios]
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> + - |
>> + gpio_fan {
>> + compatible = "gpio-fan";
>> + gpios = <&gpio1 14 1
>> + &gpio1 13 1>;
>> + gpio-fan,speed-map = <0 0
>> + 3000 1
>> + 6000 2>;
>
> Brackets needed around each pair.

Well, that's the issue. I would love to use u32-matrix, but all the
drivers use < x1 x2 y1 x2 ... z1 z2 > syntax and driver suggests it's
the right solution.
* Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
Someone had to rewrite the driver and the DTS files to fix it. We could
mark old format as deprecated and use u32-matrix, but for now with
current drivers it's not a solution.

What you think? Should I document it as it is (so u32-array)?

David

>
>> + alarm-gpios = <&gpio1 15 1>;
>> + };
>> + - |
>> + gpio_fan_cool: gpio_fan {
>> + compatible = "gpio-fan";
>> + gpios = <&gpio2 14 1
>> + &gpio2 13 1>;
>> + gpio-fan,speed-map = <0 0
>> + 3000 1
>> + 6000 2>;
>> + alarm-gpios = <&gpio2 15 1>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> --
>> 2.33.0
>>
>>


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