[PATCH 1/4] Input: ads7846: detect pen up from IRQ state

imre.deak
2006-07-03T18:29:31Z

We can't depend on the pressure value to determine when the pen was
lifted, so use the IRQ line state instead.

Signed-off-by: Imre Deak <imre.deak@solidboot.com>

---

drivers/input/touchscreen/ads7846.c | 112 +++++++++++++++++++----------------
1 files changed, 62 insertions(+), 50 deletions(-)

dfeac813257ad4941ac35a82f1996d3cd468a07e
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 4369845..94c36b1 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -370,6 +370,39 @@ static DEVICE_ATTR(disable, 0664, ads784

/*--------------------------------------------------------------------------*/

+static void ads7846_report_pen_state(struct ads7846 *ts, int down)
+{
+ struct input_dev *input_dev = ts->input;
+
+ input_report_key(input_dev, BTN_TOUCH, down);
+ if (!down)
+ input_report_abs(input_dev, ABS_PRESSURE, 0);
+#ifdef VERBOSE
+ pr_debug("%s: %s\n", ts->spi->dev.bus_id, down ? "DOWN" : "UP");
+#endif
+}
+
+static void ads7846_report_pen_position(struct ads7846 *ts, int x, int y,
+ int pressure)
+{
+ struct input_dev *input_dev = ts->input;
+
+ input_report_abs(input_dev, ABS_X, x);
+ input_report_abs(input_dev, ABS_Y, y);
+ input_report_abs(input_dev, ABS_PRESSURE, pressure);
+
+#ifdef VERBOSE
+ pr_debug("%s: %d/%d/%d\n", ts->spi->dev.bus_id, x, y, pressure);
+#endif
+}
+
+static void ads7846_sync_events(struct ads7846 *ts)
+{
+ struct input_dev *input_dev = ts->input;
+
+ input_sync(input_dev);
+}
+
/*
* PENIRQ only kicks the timer. The timer only reissues the SPI transfer,
* to retrieve touchscreen status.
@@ -381,11 +414,8 @@ static DEVICE_ATTR(disable, 0664, ads784
static void ads7846_rx(void *ads)
{
struct ads7846 *ts = ads;
- struct input_dev *input_dev = ts->input;
unsigned Rt;
- unsigned sync = 0;
u16 x, y, z1, z2;
- unsigned long flags;

/* adjust: on-wire is a must-ignore bit, a BE12 value, then padding;
* built from two 8 bit values written msb-first.
@@ -399,7 +429,7 @@ static void ads7846_rx(void *ads)
if (x == MAX_12BIT)
x = 0;

- if (likely(x && z1 && !device_suspended(&ts->spi->dev))) {
+ if (likely(x && z1)) {
/* compute touch pressure resistance using equation #2 */
Rt = z2;
Rt -= z1;
@@ -414,51 +444,31 @@ static void ads7846_rx(void *ads)
* the maximum. Don't report it to user space, repeat at least
* once more the measurement */
if (ts->tc.ignore || Rt > ts->pressure_max) {
+#ifdef VERBOSE
+ pr_debug("%s: ignored %d pressure %d\n",
+ ts->spi->dev.bus_id, ts->tc.ignore, Rt);
+#endif
mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
return;
}

- /* NOTE: "pendown" is inferred from pressure; we don't rely on
- * being able to check nPENIRQ status, or "friendly" trigger modes
- * (both-edges is much better than just-falling or low-level).
- *
- * REVISIT: some boards may require reading nPENIRQ; it's
- * needed on 7843. and 7845 reads pressure differently...
- *
- * REVISIT: the touchscreen might not be connected; this code
- * won't notice that, even if nPENIRQ never fires ...
+ /* NOTE: We can't rely on the pressure to determine the pen down
+ * state. The pressure value can fluctuate for quite a while
+ * after lifting the pen and in some cases may not even settle at
+ * the expected value. The only safe way to check for the pen up
+ * condition is in the timer by reading the pen IRQ state.
*/
- if (!ts->pendown && Rt != 0) {
- input_report_key(input_dev, BTN_TOUCH, 1);
- sync = 1;
- } else if (ts->pendown && Rt == 0) {
- input_report_key(input_dev, BTN_TOUCH, 0);
- sync = 1;
- }
-
if (Rt) {
- input_report_abs(input_dev, ABS_X, x);
- input_report_abs(input_dev, ABS_Y, y);
- sync = 1;
- }
-
- if (sync) {
- input_report_abs(input_dev, ABS_PRESSURE, Rt);
- input_sync(input_dev);
+ if (!ts->pendown) {
+ ads7846_report_pen_state(ts, 1);
+ ts->pendown = 1;
+ }
+ ads7846_report_pen_position(ts, x, y, Rt);
+ ads7846_sync_events(ts);
}

-#ifdef VERBOSE
- if (Rt || ts->pendown)
- pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
- x, y, Rt, Rt ? "" : " UP");
-#endif

- spin_lock_irqsave(&ts->lock, flags);
-
- ts->pendown = (Rt != 0);
mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
-
- spin_unlock_irqrestore(&ts->lock, flags);
}

static void ads7846_debounce(void *ads)
@@ -472,7 +482,8 @@ static void ads7846_debounce(void *ads)
m = &ts->msg[ts->msg_idx];
t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff;
- if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
+ if (ts->debounce_max && (
+ !ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol))) {
/* Repeat it, if this was the first read or the read
* wasn't consistent enough. */
if (ts->read_cnt < ts->debounce_max) {
@@ -519,14 +530,20 @@ static void ads7846_timer(unsigned long

spin_lock_irq(&ts->lock);

- if (unlikely(ts->msg_idx && !ts->pendown)) {
+ if (unlikely(!ts->get_pendown_state() ||
+ device_suspended(&ts->spi->dev))) {
+ if (ts->pendown) {
+ ads7846_report_pen_state(ts, 0);
+ ads7846_sync_events(ts);
+ ts->pendown = 0;
+ }
+
/* measurment cycle ended */
if (!device_suspended(&ts->spi->dev)) {
ts->irq_disabled = 0;
enable_irq(ts->spi->irq);
}
ts->pending = 0;
- ts->msg_idx = 0;
} else {
/* pen is still down, continue with the measurement */
ts->msg_idx = 0;
@@ -702,14 +719,9 @@ static int __devinit ads7846_probe(struc
ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
ts->pressure_max = pdata->pressure_max ? : ~0;
- if (pdata->debounce_max) {
- ts->debounce_max = pdata->debounce_max;
- ts->debounce_tol = pdata->debounce_tol;
- ts->debounce_rep = pdata->debounce_rep;
- if (ts->debounce_rep > ts->debounce_max + 1)
- ts->debounce_rep = ts->debounce_max - 1;
- } else
- ts->debounce_tol = ~0;
+ ts->debounce_max = pdata->debounce_max;
+ ts->debounce_tol = pdata->debounce_tol;
+ ts->debounce_rep = pdata->debounce_rep;
ts->get_pendown_state = pdata->get_pendown_state;

snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
--
1.2.3.g90cc1-dirty