linux-kernel - Re: [PATCH v2 1/2] dt-bindings: hwmon: Document adt7475 PWM initial duty cycle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fe5b3af9-b307-45e1-b190-ba2b3327a8df@kernel.org>
Date: Thu, 9 May 2024 09:06:49 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Chris Packham <chris.packham@...iedtelesis.co.nz>, jdelvare@...e.com,
 linux@...ck-us.net, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org
Cc: linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: hwmon: Document adt7475 PWM initial
 duty cycle

On 08/05/2024 23:55, Chris Packham wrote:
> Add documentation for the pwm-initial-duty-cycle and
> pwm-initial-frequency properties. These allow the starting state of the
> PWM outputs to be set to cater for hardware designs where undesirable
> amounts of noise is created by the default hardware state.
> 
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> ---
> 
> Notes:
>     Changes in v2:
>     - Document 0 as a valid value (leaves hardware as-is)
> 
>  .../devicetree/bindings/hwmon/adt7475.yaml    | 27 ++++++++++++++++++-
>  1 file changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/adt7475.yaml b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> index 051c976ab711..97deda082b4a 100644
> --- a/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> +++ b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> @@ -51,6 +51,30 @@ properties:
>        enum: [0, 1]
>        default: 1
>  
> +  adi,pwm-initial-duty-cycle:
> +    description: |
> +      Configures the initial duty cycle for the PWM outputs. The hardware
> +      default is 100% but this may cause unwanted fan noise at startup. Set
> +      this to a value from 0 (0% duty cycle) to 255 (100% duty cycle).
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 3
> +    maxItems: 3
> +    items:
> +      minimum: 0
> +      maximum: 255
> +      default: 255
> +
> +  adi,pwm-initial-frequency:

Frequency usually has some units, so use appropriate unit suffix and
drop $ref.  Maybe that's just target-rpm property?

But isn't this duplicating previous property? This is fan controller,
not PWM provider (in any case you miss proper $refs to pwm.yaml or
fan-common.yaml), so the only thing you initially want to configure is
the fan rotation, not specific PWM waveform. If you you want to
configure specific PWM waveform, then it's a PWM provider... but it is
not... Confused.

Best regards,
Krzysztof