linux-kernel - Re: [PATCH v6 4/5] Input: add haptic drvier on max77843

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Date:	Fri, 27 Feb 2015 09:49:41 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Jaewon Kim <jaewon02.kim@...sung.com>
Cc:	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-input@...r.kernel.org,
	Inki Dae <inki.dae@...sung.com>,
	SangBae Lee <sangbae90.lee@...sung.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Lee Jones <lee.jones@...aro.org>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Sebastian Reichel <sre@...nel.org>,
	Beomho Seo <beomho.seo@...sung.com>
Subject: Re: [PATCH v6 4/5] Input: add haptic drvier on max77843

On Thu, Feb 26, 2015 at 11:49:36AM +0900, Jaewon Kim wrote:
> Hi Dmitry,
> 
> On 26/02/2015 10:23, Dmitry Torokhov wrote:
> >Hi Jaewon,
> >
> >On Tue, Feb 24, 2015 at 10:29:07AM +0900, Jaewon Kim wrote:
> >>+static void max77843_haptic_play_work(struct work_struct *work)
> >>+{
> >>+	struct max77843_haptic *haptic =
> >>+			container_of(work, struct max77843_haptic, work);
> >>+	int error;
> >>+
> >>+	mutex_lock(&haptic->mutex);
> >>+
> >>+	if (haptic->suspended) {
> >>+		goto err_play;
> >>+	}
> >>+
> >You do not need braces around single statement. Also, this is not error
> >that you are handling, I'd prefer if we called this label out_unlock.
> You are right.
> I will change label name and remove braces.
> >>+	error = max77843_haptic_set_duty_cycle(haptic);
> >>+	if (error) {
> >>+		dev_err(haptic->dev, "failed to set duty cycle: %d\n", error);
> >>+		goto err_play;
> >>+	}
> >Do you need to configure duty cycle if you stopping the playback? Or
> >maybe disabling pwm is enough?
> 
> It do not need to set duty cycle requisitely when disabling haptic.
> 
> I will move this function to front of max77843_haptic_enable().
> 
> >
> >>+
> >>+	if (haptic->magnitude) {
> >>+		error = max77843_haptic_enable(haptic);
> >>+		if (error)
> >>+			dev_err(haptic->dev,
> >>+					"cannot enable haptic: %d\n", error);
> >>+	} else {
> >>+		max77843_haptic_disable(haptic);
> >>+		if (error)
> >>+			dev_err(haptic->dev,
> >>+					"cannot disable haptic: %d\n", error);
> >What error? You did not assign it...
> Detailed error message printed in enable/disable() function.

What I was trying to say is that you do not assign new value to 'error'
variable in this path; it still carries the value from
max77843_haptic_set_duty_cycle() above and so this "if" statement will
never work and the message will never show up.

Thanks.

-- 
Dmitry
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