Commit 1d25891f authored by Semih Hazar's avatar Semih Hazar Committed by Dmitry Torokhov
Browse files

Input: ads7846 - re-check pendown status before reporting events 



Pendown status from the PENIRQ pin is currently read only at the beginning
of a sample set. If the pen is lifted just after sampling has began then
sampled values become wrong.

This patch adds an optional platform penirq_recheck_delay attribute.  If
non-zero, samples are only reported to the input subsystem if PENIRQ is
still active that long after the samples taken.

Signed-off-by: default avatarSemih Hazar <semih.hazar@indefia.com>
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent e4f48861

drivers/input/touchscreen/ads7846.c

+15 −0
Original line number Diff line number Diff line
@@ -107,6 +107,8 @@ struct ads7846 { 
	u16			debounce_tol;

	u16			debounce_rep;



	u16			penirq_recheck_delay_usecs;



	spinlock_t		lock;

	struct hrtimer		timer;

	unsigned		pendown:1;	/* P: lock */
@@ -553,6 +555,15 @@ static void ads7846_rx(void *ads) 
		return;

	}



	/* Maybe check the pendown state before reporting. This discards

	 * false readings when the pen is lifted.

	 */

	if (ts->penirq_recheck_delay_usecs) {

		udelay(ts->penirq_recheck_delay_usecs);

		if (!ts->get_pendown_state())

			Rt = 0;

	}



	/* NOTE: We can't rely on the pressure to determine the pen down

	 * state, even this controller has a pressure sensor.  The pressure

	 * value can fluctuate for quite a while after lifting the pen and
@@ -896,6 +907,10 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
		ts->filter = ads7846_no_filter;

	ts->get_pendown_state = pdata->get_pendown_state;



	if (pdata->penirq_recheck_delay_usecs)

		ts->penirq_recheck_delay_usecs =

				pdata->penirq_recheck_delay_usecs;



	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);



	input_dev->name = "ADS784x Touchscreen";

include/linux/spi/ads7846.h

+6 −0
Original line number Diff line number Diff line
@@ -24,6 +24,12 @@ struct ads7846_platform_data { 
	 */

	u16	settle_delay_usecs;



	/* If set to non-zero, after samples are taken this delay is applied

	 * and penirq is rechecked, to help avoid false events.  This value

	 * is affected by the material used to build the touch layer.

	 */

	u16	penirq_recheck_delay_usecs;



	u16	x_plate_ohms;

	u16	y_plate_ohms;

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