linux-kernel - RE: [RESEND PATCH V13 3/3] Input: new da7280 haptic driver

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Date:   Wed, 24 Jun 2020 12:04:24 +0000
From:   Roy Im <roy.im.opensource@...semi.com>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        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: [RESEND PATCH V13 3/3] Input: new da7280 haptic driver

Hello Uwe,

On Tue, June 23, 2020 11:41 PM, Uwe Kleine-König wrote:
> 
> Hello,
> 
> On Mon, Jun 15, 2020 at 08:40:23PM +0900, Roy Im wrote:
> > Adds support for the Dialog DA7280 LRA/ERM Haptic Driver with multiple
> > mode and integrated waveform memory and wideband support.
> > It communicates via an I2C bus to the device.
> >
> > Signed-off-by: Roy Im <roy.im.opensource@...semi.com>
> 
> Just some picky comments below.
> 
> > +	error = pwm_apply_state(haptics->pwm_dev, &state);
> > +	if (error)
> > +		dev_err(haptics->dev,
> > +			"failed to apply pwm state: %pE\n",
> > +			ERR_PTR(error));
> 
> You can save some horizontal space here by dropping the \n after the first comma. (There are a few more occurences.)
> 
Ok, is this what you want?
	error = pwm_apply_state(haptics->pwm_dev, &state);
	if (error)
		dev_err(haptics->dev, "failed to apply pwm state: %pE\n",
			ERR_PTR(error));

> > +	return error;
> > +}
> > +[...]
> > +
> > +		/* Sync up PWM state and ensure it is off. */
> > +		pwm_init_state(haptics->pwm_dev, &state);
> > +		state.enabled = false;
> > +		error = pwm_apply_state(haptics->pwm_dev, &state);
> > +		if (error) {
> > +			dev_err(dev,
> > +				"failed to apply initial PWM state: %pE\n",
> > +				ERR_PTR(error));
> > +			return error;
> > +		}
> > +
> > +		/* Check PWM Period, it must be in 10k ~ 250kHz */
> 
> The unit of a PWM period is in (nano)seconds, to it cannot be in the range [10kHz, 250kHz]. (Is this too picky?)

No, it isn't. The 'Period' should be changed to 'frequency', I will fix this as below.

		/* Check PWM frequency, valid range: 10k ~ 250kHz */

> 
> > +		period2freq = 1000000 / state.period;
> > +		if (period2freq < DA7280_MIN_PWM_FREQ_KHZ ||
> > +		    period2freq > DA7280_MAX_PWM_FREQ_KHZ) {
> > +			dev_err(dev, "Not supported PWM frequency(%d)\n",
> > +				period2freq);
> 
> Doesn't the compiler warn here about period2freq being unsigned and %d being for signed int values?
> 
> For my (non-native) English ear s/Not supported/Unsupported/ sounds better. Also my eyes would be pleases by a space
> before the opening brace.

I didn't see any warning message, but I will change/improve them to proper one and the log as below.

		period2freq = 1000000 / state.period;
		if (period2freq < DA7280_MIN_PWM_FREQ_KHZ ||
		    period2freq > DA7280_MAX_PWM_FREQ_KHZ) {
			dev_err(dev, "Unsupported PWM frequency (%u)\n",
				period2freq);
			return -EINVAL;
		}
If you look ok, let me update this so.

> 
> > +			return -EINVAL;
> > +		}
> > +	}
> > +
> > +
> > +[...]
> > +static struct i2c_driver da7280_driver = {
> > +	.driver	= {
> > +		.name		= "da7280",
> > +		.of_match_table	= of_match_ptr(da7280_of_match),
> > +		.pm		= &da7280_pm_ops,
> 
> I don't like alignment of =, but I'm aware this is a subjective thing.
> (The reason for me is that adding a new member that is longer than the already existing requires touching all lines. So I
> stick to a single space before a =.)

OK, I will do as you said.

> 
> > +	},
> > +	.probe	  = da7280_probe,
> > +	.id_table = da7280_i2c_id,
> > +};
> > +module_i2c_driver(da7280_driver);
> > +
> > +MODULE_DESCRIPTION("DA7280 haptics driver"); MODULE_AUTHOR("Roy Im
> > +<Roy.Im.Opensource@...semi.com>");
> > +MODULE_LICENSE("GPL");
> > --
> > end-of-patch for RESEND PATCH V13
> 
> Best regards
> Uwe
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ |