[patch 4/9] ads7846: pin change interrupt support

[akpm@linux-foundation.org]

From: Michael Roth <mroth@nessie.de>

Some SoC supports only pin change interrupts on GPIO pins used as irq
lines.

The ads7846 core is not affected from the additional irqs on the rising
edge because the code accounts touch bounce anyway by kicking in a timer
and disabling the irq after the first request and reenabling the irq after
a timeout when there is no longer pen down detected.

Signed-off-by: Michael Roth <mroth@nessie.de>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Imre Deak <imre.deak@nokia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/input/touchscreen/ads7846.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff -puN drivers/input/touchscreen/ads7846.c~ads7846-pin-change-interrupt-support drivers/input/touchscreen/ads7846.c
--- a/drivers/input/touchscreen/ads7846.c~ads7846-pin-change-interrupt-support
+++ a/drivers/input/touchscreen/ads7846.c
@@ -1143,9 +1143,15 @@ static int __devinit ads7846_probe(struc
 
 	if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
 			spi->dev.driver->name, ts)) {
-		dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
-		err = -EBUSY;
-		goto err_free_gpio;
+		dev_info(&spi->dev,
+			"trying pin change workaround on irq %d\n", spi->irq);
+		if (request_irq(spi->irq, ads7846_irq,
+				IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
+				spi->dev.driver->name, ts)) {
+			dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
+			err = -EBUSY;
+			goto err_free_gpio;
+		}
 	}
 
 	err = ads784x_hwmon_register(spi, ts);
_