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

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Date:   Wed, 29 Jul 2020 14:09:48 +0000
From:   Roy Im <roy.im.opensource@...semi.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Uwe Kleine-Koenig <u.kleine-koenig@...gutronix.de>
CC:     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-input@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        Roy Im <roy.im.opensource@...semi.com>
Subject: RE: [PATCH v18 3/3] Input: new da7280 haptic driver

Hello Dmitry and Uwe,

Wednesday, July 29, 2020 3:37 PM, Dmitry Torokhov wrote: 

> 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.

Right, it should be %pe as you and Uwe said, Uwe suggested %pe to understand easier.. do you still prefer to stick with %d?

> 
> ...
> > +
> > +/* 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.

I will do.

> 
> > +
> > +	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...

You are right, I will use use cancel_delayed_work_sync()/duration and cancel_work_sync()/playback before scheduling playback work. And same as for the work_setgain. For setgain, there is no problem to run this regardless the 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"?

Ok, let me update so.

> 
> > +		return -EPERM;
> 
> I'd say EINVAL.

OK

> 
> > +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?

I have carefully reviewed my driver again with your comments, now the upload effect covers this attributes, so I would like to remove them and add some code more for gpi_seq_idx update.

Thanks for your comments.

Kinds regards,
Roy