linux-kernel - Re: [PATCH V9 3/3] Input: new da7280 haptic driver

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Message-ID: <20200301212025.lw4f6uv453oulu22@pengutronix.de>
Date:   Sun, 1 Mar 2020 22:20:25 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Roy Im <roy.im.opensource@...semi.com>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Brian Masney <masneyb@...tation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Lee Jones <lee.jones@...aro.org>, Luca Weiss <luca@...tu.xyz>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Pascal PAILLET-LME <p.paillet@...com>,
        Rob Herring <robh@...nel.org>,
        Samuel Ortiz <sameo@...ux.intel.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Support Opensource <Support.Opensource@...semi.com>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH V9 3/3] Input: new da7280 haptic driver

Hello Roy,

On Sat, Feb 29, 2020 at 12:59:20AM +0000, Roy Im wrote:
> Okay, thanks. I have tried to update that as below.
> Could I get your comment if you still see anything on this?
> 
> 	/* Maximum gain is 0x7fff for PWM mode */
> 	#define MAX_MAGNITUDE_SHIFT		15
>        [...]
> 	period_mag_multi >>= MAX_MAGNITUDE_SHIFT;
> 
> 	/* The interpretation of duty cycle depends on the acc_en,
> 	* it should be from 50% to 100% for acc_en = 0.
> 	* See datasheet 'PWM mode' section for more details.
> 	*/
> 	if (!haptics->acc_en) {
> 		period_mag_multi += state.period;
> 		period_mag_multi /= 2;
> 	}

Much better. Extra points if you add a link to the datasheet at the
top of the driver. I didn't look at the datasheet and assume that the
reasoning is obvious then.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |