Input: ads7846 - debouncing and rudimentary sample filtering
Some touchscreens seem to oscillate heavily for a while after touching
the screen. Implement support for sampling the screen until we get two
consecutive values that are close enough.
Signed-off-by: Imre Deak <imre.deak@nokia.com>
Signed-off-by: Juha Yrjola <juha.yrjola@nokia.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 54d4334..8670cd1 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -77,7 +77,13 @@
struct ts_event tc;
struct spi_transfer xfer[10];
- struct spi_message msg;
+ struct spi_message msg[5];
+ int msg_idx;
+ int read_cnt;
+ int last_read;
+
+ u16 debounce_max;
+ u16 debounce_tol;
spinlock_t lock;
struct timer_list timer; /* P: lock */
@@ -167,7 +173,7 @@
if (!req)
return -ENOMEM;
- INIT_LIST_HEAD(&req->msg.transfers);
+ spi_message_init(&req->msg);
/* activate reference, so it has time to settle; */
req->ref_on = REF_ON;
@@ -344,31 +350,76 @@
spin_unlock_irqrestore(&ts->lock, flags);
}
+static void ads7846_debounce(void *ads)
+{
+ struct ads7846 *ts = ads;
+ struct spi_message *m;
+ struct spi_transfer *t;
+ u16 val;
+ int status;
+
+ m = &ts->msg[ts->msg_idx];
+ t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
+ val = (*(u16 *)t->rx_buf) >> 3;
+
+ if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol
+ && ts->read_cnt < ts->debounce_max)) {
+ /* Repeat it, if this was the first read or the read wasn't
+ * consistent enough
+ */
+ ts->read_cnt++;
+ ts->last_read = val;
+ } else {
+ /* Go for the next read */
+ ts->msg_idx++;
+ ts->read_cnt = 0;
+ m++;
+ }
+ status = spi_async(ts->spi, m);
+ if (status)
+ dev_err(&ts->spi->dev, "spi_async --> %d\n",
+ status);
+}
+
static void ads7846_timer(unsigned long handle)
{
struct ads7846 *ts = (void *)handle;
int status = 0;
- unsigned long flags;
- spin_lock_irqsave(&ts->lock, flags);
- if (!ts->pending) {
- ts->pending = 1;
- if (!ts->irq_disabled) {
- ts->irq_disabled = 1;
- disable_irq(ts->spi->irq);
- }
- status = spi_async(ts->spi, &ts->msg);
- if (status)
- dev_err(&ts->spi->dev, "spi_async --> %d\n",
- status);
- }
- spin_unlock_irqrestore(&ts->lock, flags);
+ ts->msg_idx = 0;
+ status = spi_async(ts->spi, &ts->msg[0]);
+ if (status)
+ dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
}
static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
{
- ads7846_timer((unsigned long) handle);
- return IRQ_HANDLED;
+ struct ads7846 *ts = handle;
+ unsigned long flags;
+ int r = IRQ_HANDLED;
+
+ spin_lock_irqsave(&ts->lock, flags);
+ if (ts->irq_disabled)
+ r = IRQ_HANDLED;
+ else {
+ if (!ts->irq_disabled) {
+ /* REVISIT irq logic for many ARM chips has cloned a
+ * bug wherein disabling an irq in its handler won't
+ * work;(it's disabled lazily, and too late to work.
+ * until all their irq logic is fixed, we must shadow
+ * that state here.
+ */
+ ts->irq_disabled = 1;
+
+ disable_irq(ts->spi->irq);
+ }
+ if (!ts->pending) {
+ ts->pending = 1;
+ mod_timer(&ts->timer, jiffies);
+ }
+ }
+ spin_unlock_irqrestore(&ts->lock, flags);
+ return r;
}
/*--------------------------------------------------------------------------*/
@@ -426,6 +477,7 @@
struct ads7846 *ts;
struct input_dev *input_dev;
struct ads7846_platform_data *pdata = spi->dev.platform_data;
+ struct spi_message *m;
struct spi_transfer *x;
int err;
@@ -472,6 +524,8 @@
ts->model = pdata->model ? : 7846;
ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
+ ts->debounce_max = pdata->debounce_max ? : 1;
+ ts->debounce_tol = pdata->debounce_tol ? : 10;
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
@@ -495,72 +549,98 @@
/* set up the transfers to read touchscreen state; this assumes we
* use formula #2 for pressure, not #3.
*/
- INIT_LIST_HEAD(&ts->msg.transfers);
+ m = &ts->msg[0];
x = ts->xfer;
+ spi_message_init(m);
+
/* y- still on; turn on only y+ (and ADC) */
ts->read_y = READ_Y;
x->tx_buf = &ts->read_y;
x->len = 1;
- spi_message_add_tail(x, &ts->msg);
+ spi_message_add_tail(x, m);
x++;
x->rx_buf = &ts->tc.y;
x->len = 2;
- spi_message_add_tail(x, &ts->msg);
+ spi_message_add_tail(x, m);
- /* turn y+ off, x- on; we'll use formula #2 */
- if (ts->model == 7846) {
- x++;
- ts->read_z1 = READ_Z1;
- x->tx_buf = &ts->read_z1;
- x->len = 1;
- spi_message_add_tail(x, &ts->msg);
+ m->complete = ads7846_debounce;
+ m->context = ts;
- x++;
- x->rx_buf = &ts->tc.z1;
- x->len = 2;
- spi_message_add_tail(x, &ts->msg);
-
- x++;
- ts->read_z2 = READ_Z2;
- x->tx_buf = &ts->read_z2;
- x->len = 1;
- spi_message_add_tail(x, &ts->msg);
-
- x++;
- x->rx_buf = &ts->tc.z2;
- x->len = 2;
- spi_message_add_tail(x, &ts->msg);
- }
+ m++;
+ spi_message_init(m);
/* turn y- off, x+ on, then leave in lowpower */
x++;
ts->read_x = READ_X;
x->tx_buf = &ts->read_x;
x->len = 1;
- spi_message_add_tail(x, &ts->msg);
+ spi_message_add_tail(x, m);
x++;
x->rx_buf = &ts->tc.x;
x->len = 2;
- spi_message_add_tail(x, &ts->msg);
+ spi_message_add_tail(x, m);
+
+ m->complete = ads7846_debounce;
+ m->context = ts;
+
+ /* turn y+ off, x- on; we'll use formula #2 */
+ if (ts->model == 7846) {
+ m++;
+ spi_message_init(m);
+
+ x++;
+ ts->read_z1 = READ_Z1;
+ x->tx_buf = &ts->read_z1;
+ x->len = 1;
+ spi_message_add_tail(x, m);
+
+ x++;
+ x->rx_buf = &ts->tc.z1;
+ x->len = 2;
+ spi_message_add_tail(x, m);
+
+ m->complete = ads7846_debounce;
+ m->context = ts;
+
+ m++;
+ spi_message_init(m);
+
+ x++;
+ ts->read_z2 = READ_Z2;
+ x->tx_buf = &ts->read_z2;
+ x->len = 1;
+ spi_message_add_tail(x, m);
+
+ x++;
+ x->rx_buf = &ts->tc.z2;
+ x->len = 2;
+ spi_message_add_tail(x, m);
+
+ m->complete = ads7846_debounce;
+ m->context = ts;
+ }
/* power down */
+ m++;
+ spi_message_init(m);
+
x++;
ts->pwrdown = PWRDOWN;
x->tx_buf = &ts->pwrdown;
x->len = 1;
- spi_message_add_tail(x, &ts->msg);
+ spi_message_add_tail(x, m);
x++;
x->rx_buf = &ts->dummy;
x->len = 2;
CS_CHANGE(*x);
- spi_message_add_tail(x, &ts->msg);
+ spi_message_add_tail(x, m);
- ts->msg.complete = ads7846_rx;
- ts->msg.context = ts;
+ m->complete = ads7846_rx;
+ m->context = ts;
if (request_irq(spi->irq, ads7846_irq,
SA_SAMPLE_RANDOM | SA_TRIGGER_FALLING,