Input: ads7846: detect pen up from IRQ state

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>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 4ec7875705206e33a9e0bb70e1a3f17293b8ad9c..94c36b1a7f2600221e888cd880150a6a11151a3b 100644 (file)
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -370,6 +370,39 @@ static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);
 
 /*--------------------------------------------------------------------------*/
 
+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, ads7846_disable_show, ads7846_disable_store);
 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)
@@ -520,14 +530,20 @@ static void ads7846_timer(unsigned long handle)
 
        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;