mxc_ts: improved wait on irq support, avoding a race condition

This commit improves (but not fixes) a problem detected with the touch
driver, that was missing an interrupt condition (a pen down after a pen up)
and was causing that the driver were not able to detect additional interrupts
if the pen was down, because there were no new interrupts generated.

Thsi workarounds the problem by forcing the driver to wait on interrupts only
after 2 consecutive pen-up samples. This seems to fix the problem, but its
not 100 sure because the problem has not been analyzed with enough detail.

Signed-off-by: Pedro Perez de Heredia <pedro.perez@digi.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/input/touchscreen/mxc_ts.c b/drivers/input/touchscreen/mxc_ts.c
index b354d81c5465..d60cd51a535e 100644
--- a/drivers/input/touchscreen/mxc_ts.c
+++ b/drivers/input/touchscreen/mxc_ts.c
@@ -44,14 +44,17 @@ static u32 input_ts_installed;
 static int ts_thread(void *arg)
 {
 	t_touch_screen ts_sample;
-	s32 wait = 0;
+	s32 wait = 0, wait2 = 0;
 
 	daemonize("mxc_ts");
 	while (input_ts_installed) {
 		try_to_freeze();
 		memset(&ts_sample, 0, sizeof(t_touch_screen));
-		if (0 != pmic_adc_get_touch_sample(&ts_sample, !wait))
+		
+		/* After 2 consecutive samples with the pen up, enable irq waiting */
+		if (0 != pmic_adc_get_touch_sample(&ts_sample, !(wait + wait2))) {
 			continue;
+		}
 		if (!(ts_sample.contact_resistance || wait))
 			continue;
 
@@ -60,7 +63,7 @@ static int ts_thread(void *arg)
 		input_report_abs(mxc_inputdev, ABS_PRESSURE,
 				 ts_sample.contact_resistance);
 		input_sync(mxc_inputdev);
-
+		wait2 = wait;
 		wait = ts_sample.contact_resistance;
 		msleep(20);
 	}