Date: Wed, 30 Mar 2016 15:01:49 -0700
From: Stephen Boyd <sboyd@codeaurora.org>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Thierry Reding <thierry.reding@gmail.com>, linux-pwm@vger.kernel.org,
        Mike Turquette <mturquette@baylibre.com>, linux-clk@vger.kernel.org,
        Mark Brown <broonie@kernel.org>, Liam Girdwood <lgirdwood@gmail.com>,
        Kamil Debski <k.debski@samsung.com>, lm-sensors@lm-sensors.org,
        Jean Delvare <jdelvare@suse.com>, Guenter Roeck <linux@roeck-us.net>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        linux-input@vger.kernel.org, Bryan Wu <cooloney@gmail.com>,
        Richard Purdie <rpurdie@rpsys.net>,
        Jacek Anaszewski <j.anaszewski@samsung.com>,
        linux-leds@vger.kernel.org,
        Maxime Ripard <maxime.ripard@free-electrons.com>,
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        Joachim Eastwood <manabian@gmail.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
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        Jingoo Han <jingoohan1@gmail.com>, Lee Jones <lee.jones@linaro.org>,
        linux-fbdev@vger.kernel.org,
        Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Robert Jarzmik <robert.jarzmik@free.fr>,
        Alexandre Belloni <alexandre.belloni@free-electrons.com>,
        Kukjin Kim <kgene@kernel.org>,
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        linux-samsung-soc@vger.kernel.org, intel-gfx@lists.freedesktop.org,
        Daniel Vetter <daniel.vetter@intel.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org,
        Hartley Sweeten <hsweeten@visionengravers.com>,
        Ryan Mallon <rmallon@gmail.com>, Alexander Shiyan <shc_work@mail.ru>,
        Milo Kim <milo.kim@ti.com>
Subject: Re: [PATCH v5 34/46] clk: pwm: switch to the atomic API
Message-ID: <20160330220149.GU18567@codeaurora.org>
References: <1459368249-13241-1-git-send-email-boris.brezillon@free-electrons.com>
 <1459368249-13241-35-git-send-email-boris.brezillon@free-electrons.com>
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On 03/30, Boris Brezillon wrote:
> diff --git a/drivers/clk/clk-pwm.c b/drivers/clk/clk-pwm.c
> index ebcd738..49ec5b1 100644
> --- a/drivers/clk/clk-pwm.c
> +++ b/drivers/clk/clk-pwm.c
> @@ -28,15 +28,29 @@ static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
>  static int clk_pwm_prepare(struct clk_hw *hw)
>  {
>  	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
> +	struct pwm_state pstate;
>  
> -	return pwm_enable(clk_pwm->pwm);
> +	pwm_get_state(clk_pwm->pwm, &pstate);
> +	if (pstate.enabled)
> +		return 0;
> +
> +	pstate.enabled = true;
> +
> +	return pwm_apply_state(clk_pwm->pwm, &pstate);

This doesn't seem atomic anymore if we're checking the state and
then not calling apply_state if it's already enabled. But I
assume this doesn't matter because we "own" the pwm here?
Otherwise I would think this would be unconditional apply state
and duplicates would be ignored in the pwm framework.

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