linux-kernel - Re: [PATCH v2 1/3] pwm: make it possible to apply pwm changes in atomic context

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Message-ID: <ZSkvTKr42sUZImiM@orome.fritz.box>
Date:   Fri, 13 Oct 2023 13:51:40 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Sean Young <sean@...s.org>
Cc:     linux-media@...r.kernel.org,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-pwm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] pwm: make it possible to apply pwm changes in
 atomic context

On Fri, Oct 13, 2023 at 11:46:14AM +0100, Sean Young wrote:
[...]
> diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> index d2f9f690a9c1..93f166ab03c1 100644
> --- a/include/linux/pwm.h
> +++ b/include/linux/pwm.h
> @@ -267,6 +267,7 @@ struct pwm_capture {
>   * @get_state: get the current PWM state. This function is only
>   *	       called once per PWM device when the PWM chip is
>   *	       registered.
> + * @atomic: can the driver execute pwm_apply_state in atomic context
>   * @owner: helps prevent removal of modules exporting active PWMs
>   */
>  struct pwm_ops {
> @@ -278,6 +279,7 @@ struct pwm_ops {
>  		     const struct pwm_state *state);
>  	int (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
>  			 struct pwm_state *state);
> +	bool atomic;
>  	struct module *owner;
>  };

As I mentioned earlier, this really belongs in struct pwm_chip rather
than struct pwm_ops. I know that Uwe said this is unlikely to happen,
and that may be true, but at the same time it's not like I'm asking
much. Whether you put this in struct pwm_ops or struct pwm_chip is
about the same amount of code, and putting it into pwm_chip is much
more flexible, so it's really a no-brainer.

Thierry

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