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Subject: Re: [PATCH v4 8/9] Input: atmel_mxt_ts - add support for reference
 data
To: Hans Verkuil <hverkuil@xs4all.nl>
References: <1466172988-3698-1-git-send-email-nick.dyer@itdev.co.uk>
 <1466172988-3698-9-git-send-email-nick.dyer@itdev.co.uk>
 <5768152E.7070905@xs4all.nl>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Benson Leung <bleung@chromium.org>,
        Alan Bowens <Alan.Bowens@atmel.com>,
        Javier Martinez Canillas <javier@osg.samsung.com>,
        Chris Healy <cphealy@gmail.com>, Henrik Rydberg <rydberg@bitmath.org>,
        Andrew Duggan <aduggan@synaptics.com>,
        James Chen <james.chen@emc.com.tw>, Dudley Du <dudl@cypress.com>,
        Andrew de los Reyes <adlr@chromium.org>, sheckylin@chromium.org,
        Peter Hutterer <peter.hutterer@who-t.net>,
        Florian Echtler <floe@butterbrot.org>, mchehab@osg.samsung.com
From: Nick Dyer <nick.dyer@itdev.co.uk>
Message-ID: <d5a7f130-ef12-2e1d-c842-eef62899a31a@itdev.co.uk>
Date: Mon, 20 Jun 2016 17:18:30 +0100
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On 20/06/2016 17:09, Hans Verkuil wrote:
> On 06/17/2016 04:16 PM, Nick Dyer wrote:
>> @@ -2325,11 +2344,20 @@ static int mxt_vidioc_querycap(struct file *file, void *priv,
>>  static int mxt_vidioc_enum_input(struct file *file, void *priv,
>>  				   struct v4l2_input *i)
>>  {
>> -	if (i->index > 0)
>> +	if (i->index >= MXT_V4L_INPUT_MAX)
>>  		return -EINVAL;
>>  
>>  	i->type = V4L2_INPUT_TYPE_TOUCH_SENSOR;
>> -	strlcpy(i->name, "Mutual References", sizeof(i->name));
>> +
>> +	switch (i->index) {
>> +	case MXT_V4L_INPUT_REFS:
>> +		strlcpy(i->name, "Mutual References", sizeof(i->name));
>> +		break;
>> +	case MXT_V4L_INPUT_DELTAS:
>> +		strlcpy(i->name, "Mutual Deltas", sizeof(i->name));
> 
> I don't think this name is very clear. I have no idea how to interpret "Mutual"
> in this context.

"Mutual" is a touch domain specific term, it means the delta value is for
the capacitance between the horizontal and vertical lines at a particular
"node" on the touchscreen matrix, see
https://en.wikipedia.org/wiki/Touchscreen#Mutual_capacitance

I'll put in a comment.

> 
>> +		break;
>> +	}
>> +
>>  	return 0;
>>  }
>>  
>> @@ -2337,12 +2365,16 @@ static int mxt_set_input(struct mxt_data *data, unsigned int i)
>>  {
>>  	struct v4l2_pix_format *f = &data->dbg.format;
>>  
>> -	if (i > 0)
>> +	if (i >= MXT_V4L_INPUT_MAX)
>>  		return -EINVAL;
>>  
>> +	if (i == MXT_V4L_INPUT_DELTAS)
>> +		f->pixelformat = V4L2_PIX_FMT_YS16;
>> +	else
>> +		f->pixelformat = V4L2_PIX_FMT_Y16;
> 
> You probably need a V4L2_TOUCH_FMT_U16 or something for this as well. It certainly
> needs to be documented.

OK, will change this.