linux-kernel - Re: [PATCH v18 3/3] Input: new da7280 haptic driver

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Date:   Tue, 28 Jul 2020 23:36:38 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Roy Im <roy.im.opensource@...semi.com>
Cc:     Uwe Kleine-Koenig <u.kleine-koenig@...gutronix.de>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Brian Masney <masneyb@...tation.org>,
        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-kernel@...r.kernel.org,
        linux-pwm@...r.kernel.org
Subject: Re: [PATCH v18 3/3] Input: new da7280 haptic driver

Hi Roy,

On Wed, Jul 29, 2020 at 11:59:40AM +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.

A few questions/suggestions...

> 
> Reviewed-by: Jes Sorensen <Jes.Sorensen@...il.com>.
> 
> Signed-off-by: Roy Im <roy.im.opensource@...semi.com>
> 
> ---
> v18:
> 	- Corrected comments in Kconfig
> 	- Updated to preferred style for multi line comments in c file.
> v17:
> 	- fixed an issue.
> v16:
> 	- Corrected some code and updated description in Kconfig.
> v15:
> 	- Removed some defines and updated some comments.
> v14:
> 	- Updated pwm related code, alignments and comments.
> v13:
> 	- Updated some conditions in pwm function and alignments.
> v12: No changes.
> v11: 
> 	- Updated the pwm related code, comments and typo.
> v10: 
> 	- Updated the pwm related function and added some comments.
> v9: 
> 	- Removed the header file and put the definitions into the c file.
> 	- Updated the pwm code and error logs with %pE

I believe the %pE is to format an escaped buffer, you probably want to
%pe (lowercase) to print errors. I am also not quite sure if we want to
use it in cases when we have non-pointer error, or we should stick with
%d as most of the kernel does.

...
> +
> +/* DA7280_ACTUATOR3 (Address 0x0e) */
> +#define DA7280_IMAX_MASK			(31 << 0)

We have GENMASK(h,l) macro in include/linux/bits.h that could be used
here and in other mask definitions.

> +
> +	bool legacy;
> +	struct delayed_work work_duration;
> +	struct work_struct work_playback;
> +	struct work_struct work_setgain;

How do we ensure that all these works do not clash with each other?
As far as I can see we could have the "duration" work executing
simultaneously with playback...

> +static int da7280_haptics_playback(struct input_dev *dev,
> +				   int effect_id, int val)
> +{
> +	struct da7280_haptic *haptics = input_get_drvdata(dev);
> +
> +	if (!haptics->op_mode) {
> +		dev_warn(haptics->dev,
> +			 "Any effects are not uploaded yet\n");

"No effects have been uploaded"?

> +		return -EPERM;

I'd say EINVAL.

> +static DEVICE_ATTR_RW(ps_seq_id);
> +static DEVICE_ATTR_RW(ps_seq_loop);
> +static DEVICE_ATTR_RW(gpi_seq_id0);
> +static DEVICE_ATTR_RW(gpi_seq_id1);
> +static DEVICE_ATTR_RW(gpi_seq_id2);
> +static DEVICE_ATTR_WO(patterns);

Should this be a binary attribute instead of having string parsing in
the kernel?

Thanks.

-- 
Dmitry