linux-kernel - Re: [PATCH v5 36/46] input: misc: max77693: switch to the atomic API

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Message-ID: <20160331174801.GC39098@dtor-ws>
Date:	Thu, 31 Mar 2016 10:48:01 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	Thierry Reding <thierry.reding@...il.com>,
	linux-pwm@...r.kernel.org,
	Mike Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Kamil Debski <k.debski@...sung.com>, lm-sensors@...sensors.org,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	linux-input@...r.kernel.org, Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Jacek Anaszewski <j.anaszewski@...sung.com>,
	linux-leds@...r.kernel.org,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>, linux-sunxi@...glegroups.com,
	Joachim Eastwood <manabian@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Heiko Stuebner <heiko@...ech.de>,
	linux-rockchip@...ts.infradead.org,
	Jingoo Han <jingoohan1@...il.com>,
	Lee Jones <lee.jones@...aro.org>, linux-fbdev@...r.kernel.org,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
	David Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
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	Hartley Sweeten <hsweeten@...ionengravers.com>,
	Ryan Mallon <rmallon@...il.com>,
	Alexander Shiyan <shc_work@...l.ru>, Milo Kim <milo.kim@...com>
Subject: Re: [PATCH v5 36/46] input: misc: max77693: switch to the atomic API

Hi Boris,

On Wed, Mar 30, 2016 at 10:03:59PM +0200, Boris Brezillon wrote:
> pwm_config/enable/disable() have been deprecated and should be replaced
> by pwm_apply_state().
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> ---
>  drivers/input/misc/max77693-haptic.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/input/misc/max77693-haptic.c b/drivers/input/misc/max77693-haptic.c
> index cf6aac0..aef7dc4 100644
> --- a/drivers/input/misc/max77693-haptic.c
> +++ b/drivers/input/misc/max77693-haptic.c
> @@ -70,13 +70,16 @@ struct max77693_haptic {
>  
>  static int max77693_haptic_set_duty_cycle(struct max77693_haptic *haptic)
>  {
> +	struct pwm_state pstate;
>  	struct pwm_args pargs = { };
> -	int delta;
>  	int error;
>  
>  	pwm_get_args(haptic->pwm_dev, &pargs);
> -	delta = (pargs.period + haptic->pwm_duty) / 2;
> -	error = pwm_config(haptic->pwm_dev, delta, pargs.period);
> +	pwm_get_state(haptic->pwm_dev, &pstate);
> +
> +	pstate.period = pargs.period;
> +	pstate.duty_cycle = (pargs.period + haptic->pwm_duty) / 2;
> +	error = pwm_apply_state(haptic->pwm_dev, &pstate);

This does not make sense with regard to the atomic API. If you look in
max77693_haptic_play_work(), right after calling
max77693_haptic_set_duty_cycle() we either try to enable or disable the
pwm. When switching to this new API we should combine both actions.

>  	if (error) {
>  		dev_err(haptic->dev, "failed to configure pwm: %d\n", error);
>  		return error;
> @@ -161,12 +164,16 @@ static int max77693_haptic_lowsys(struct max77693_haptic *haptic, bool enable)
>  
>  static void max77693_haptic_enable(struct max77693_haptic *haptic)
>  {
> +	struct pwm_state pstate;
>  	int error;
>  
>  	if (haptic->enabled)
>  		return;
>  
> -	error = pwm_enable(haptic->pwm_dev);
> +	pwm_get_state(haptic->pwm_dev, &pstate);
> +	pstate.enabled = true;
> +
> +	error = pwm_apply_state(haptic->pwm_dev, &pstate);

As I mentioned I'd rather we did not deprecate pwm_enable() and
pwm_disable() (and maybe others), as it forces us to add unnecessary
boilerplate code to the drivers.
 
>  	if (error) {
>  		dev_err(haptic->dev,
>  			"failed to enable haptic pwm device: %d\n", error);
> @@ -188,11 +195,13 @@ static void max77693_haptic_enable(struct max77693_haptic *haptic)
>  err_enable_config:
>  	max77693_haptic_lowsys(haptic, false);
>  err_enable_lowsys:
> -	pwm_disable(haptic->pwm_dev);
> +	pstate.enabled = false;
> +	pwm_apply_state(haptic->pwm_dev, &pstate);
>  }
>  
>  static void max77693_haptic_disable(struct max77693_haptic *haptic)
>  {
> +	struct pwm_state pstate;
>  	int error;
>  
>  	if (!haptic->enabled)
> @@ -206,7 +215,9 @@ static void max77693_haptic_disable(struct max77693_haptic *haptic)
>  	if (error)
>  		goto err_disable_lowsys;
>  
> -	pwm_disable(haptic->pwm_dev);
> +	pwm_get_state(haptic->pwm_dev, &pstate);
> +	pstate.enabled = false;
> +	pwm_apply_state(haptic->pwm_dev, &pstate);

Same here.

>  	haptic->enabled = false;
>  
>  	return;
> -- 
> 2.5.0
> 

Thanks.

-- 
Dmitry