Re: [PATCH v8 4/8] dt-bindings: pwm: Support new PWM_USAGE_POWER flag

From: Thierry Reding
Date: Fri Apr 16 2021 - 09:54:35 EST


On Mon, Apr 12, 2021 at 03:27:41PM +0200, Clemens Gruber wrote:
> Add the flag and corresponding documentation for PWM_USAGE_POWER.
>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Signed-off-by: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/pwm/pwm.txt | 3 +++
> include/dt-bindings/pwm/pwm.h | 1 +
> 2 files changed, 4 insertions(+)

Rob, what are your thoughts on this? I've been thinking about this some
more and I'm having second thoughts about putting this into device tree
because it doesn't actually describe a property of the PWM hardware but
rather a use-case specific hint. It's a bit of a gray area because this
is just part of the PWM specifier which already has use-case specific
"configuration", such as the period and the polarity.

Perhaps a better place for this is within the PWM API? We could add the
same information into struct pwm_state and then consumers that don't
care about specifics of the signal (such as pwm-backlight) can set that
flag when they request a state to be applied.

Thierry

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