linux-kernel - Re: [RFC PATCH 2/7] dt-bindings: pwm: document the PWM polarity flag

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Date:   Wed, 18 Mar 2020 00:58:56 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Oleksandr Suvorov <oleksandr.suvorov@...adex.com>
Cc:     devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
        Paul Barker <pbarker@...sulko.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Igor Opaniuk <igor.opaniuk@...adex.com>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/7] dt-bindings: pwm: document the PWM polarity flag

Hi Oleksandr,

Thank you for the patch.

On Tue, Mar 17, 2020 at 02:32:26PM +0200, Oleksandr Suvorov wrote:
> Add the description of PWM_POLARITY_NORMAL flag.
> 
> Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@...adex.com>
> ---
> 
>  Documentation/devicetree/bindings/pwm/pwm.txt | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt
> index 084886bd721e..440c6b9a6a4e 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm.txt
> @@ -46,6 +46,7 @@ period in nanoseconds.
>  Optionally, the pwm-specifier can encode a number of flags (defined in
>  <dt-bindings/pwm/pwm.h>) in a third cell:
>  - PWM_POLARITY_INVERTED: invert the PWM signal polarity
> +- PWM_POLARITY_NORMAL: don't invert the PWM signal polarity

With the previous line mentioning that the pwm-specifier can encode a
number of *flags*, this becomes confusing: reading the documentation
only and not pwm.h, one could wonder what happens if none or both of
PWM_POLARITY_INVERTED and PWM_POLARITY_NORMAL are specified :-(

>  
>  Example with optional PWM specifier for inverse polarity
>  

-- 
Regards,

Laurent Pinchart