diff options
| author | Semih Hazar <semih.hazar@indefia.com> | 2007-07-18 00:36:04 -0400 |
|---|---|---|
| committer | Dmitry Torokhov <dtor@insightbb.com> | 2007-07-18 00:36:04 -0400 |
| commit | 1d25891f3241103d14ea78236504474a138b8ada (patch) | |
| tree | caeef0ea5f41eae2a005b6eab642e823d4791a0f | |
| parent | e4f48861993294c27849076741eb0c090482560b (diff) | |
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: Semih Hazar <semih.hazar@indefia.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
| -rw-r--r-- | drivers/input/touchscreen/ads7846.c | 15 | ||||
| -rw-r--r-- | include/linux/spi/ads7846.h | 6 |
2 files changed, 21 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index 103ee6ad299..96581d08774 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -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"; diff --git a/include/linux/spi/ads7846.h b/include/linux/spi/ads7846.h index a44fa7a02bd..334d3141162 100644 --- a/include/linux/spi/ads7846.h +++ b/include/linux/spi/ads7846.h @@ -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; |