Re: [PATCH 1/4] input: touchscreen: ti_am335x_tsc Interchange touchscreen and ADC steps

From: Vignesh R <vigneshr@ti.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	Kumar Gala <galak@codeaurora.org>,
	Benoit Cousson <bcousson@baylibre.com>,
	Tony Lindgren <tony@atomide.com>,
	Russell King <linux@arm.linux.org.uk>,
	Jonathan Cameron <jic23@kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	<devicetree@vger.kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Jan Kardell <jan.kardell@telliq.com>, <linux-iio@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	<linux-input@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Felipe Balbi <balbi@ti.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Peter Meerwald <pmeerw@pmeerw.net>,
	Hartmut Knaack <knaack.h@gmx.de>, <linux-omap@vger.kernel.org>,
	Lee Jones <lee.jones@linaro.org>,
	<linux-arm-kernel@lists.infradead.org>,
	Brad Griffis <bgriffis@ti.com>
Subject: Re: [PATCH 1/4] input: touchscreen: ti_am335x_tsc Interchange touchscreen and ADC steps
Date: Fri, 7 Nov 2014 11:04:05 +0530	[thread overview]
Message-ID: <545C59CD.3070707@ti.com> (raw)
In-Reply-To: <20141106141916.GA17151@netboy>

On Thursday 06 November 2014 07:49 PM, Richard Cochran wrote:
> On Mon, Oct 27, 2014 at 04:38:28PM +0530, Vignesh R wrote:
> 
> ...
> 
>> @@ -209,6 +214,7 @@ static void titsc_read_coordinates(struct titsc *ts_dev,
>>  	unsigned int read, diff;
>>  	unsigned int i, channel;
>>  	unsigned int creads = ts_dev->coordinate_readouts;
>> +	unsigned int first_step = TOTAL_STEPS - (creads * 2 + 2);
>>  
>>  	*z1 = *z2 = 0;
>>  	if (fifocount % (creads * 2 + 2))
>> @@ -226,7 +232,7 @@ static void titsc_read_coordinates(struct titsc *ts_dev,
>>  
>>  		channel = (read & 0xf0000) >> 16;
>>  		read &= 0xfff;
>> -		if (channel < creads) {
>> +		if (channel > first_step + creads + 2) {
>>  			diff = abs(read - prev_val_x);
>>  			if (diff < prev_diff_x) {
>>  				prev_diff_x = diff;
>> @@ -234,19 +240,19 @@ static void titsc_read_coordinates(struct titsc *ts_dev,
>>  			}
>>  			prev_val_x = read;
>>  
>> -		} else if (channel < creads * 2) {
>> +		} else if (channel == first_step + creads + 1) {
>> +			*z1 = read;
>> +
>> +		} else if (channel == first_step + creads + 2) {
>> +			*z2 = read;
>> +
>> +		} else if (channel > first_step) {
>>  			diff = abs(read - prev_val_y);
>>  			if (diff < prev_diff_y) {
>>  				prev_diff_y = diff;
>>  				*y = read;
> 
> While you are at it, please get rid of the this "delta filter"
> nonsense.

Currently, there is too much noise in the TSC hardware that is being
removed by delta filtering. I tested TSC unit by removing filtering
logic, the performance was not at all satisfactory. The cursor jumps
wayward and smooth circles cannot be drawn. Looks like delta filtering
cannot be removed as of now. May be I will try and address it in future.

Regards
Vignesh

> 
> Thanks,
> Richard
> 
>>  			}
>>  			prev_val_y = read;
>> -
>> -		} else if (channel < creads * 2 + 1) {
>> -			*z1 = read;
>> -
>> -		} else if (channel < creads * 2 + 2) {
>> -			*z2 = read;
>>  		}
>>  	}
>>  }
>> -- 
>> 1.9.1
>>
>>
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